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First time eDrive and xDrive tech has been combined in one vehicle

BMW has unveiled the Concept X5 eDrive, which will be showcased at the New York International Auto Show. Although the vehicle is labeled as a concept, it’s a dead ringer for the production plug-in hybrid version of BMW’s popular crossover that it plans to bring to market sometime within the next year or two.
 
The hybrid drive system gets its primary motivation from a 245hp turbocharged 4-cylinder engine. That gas engine is combined with a 95hp/184 lb-ft electric motor developed by the BMW Group. Power for the electric motor comes from a lithium-ion battery pack (which is mounted under the cargo area) that can charge from any wall outlet.
 
The Concept X5 eDrive can drive on electricity alone for up to 20 miles at speeds up to 75 mph. BMW says that the car will have an average fuel consumption of over 74.3 mpg in the EU testing cycle (which means we’ll likely see less than half of that quoted figure under EPA guidelines). BMW says that the X5 concept can reach 62mph in under 7-seconds.

 
The Concept X5 eDrive is the first from BMW that uses its xDrive all-wheel-drive system paired with eDrive hybrid technology.
 
The concept also has a ConnectedDrive system that helps plan routes and lists the location of charging stations on the GPS map. This allows the driver to find a charging station when they are around town in electric mode.

Source: BMW



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RE: Tesla!
By EricMartello on 4/15/2014 4:28:00 PM , Rating: 2
quote:
From your link that you obviously didn't read:
The total range -- adding the unused 4 miles, would be 238. Yes, 238 is 11 percent short of 265. Moreover, it was done while being very stingy with performance (for the most part). Is that 265 actually valid? If you drive predominately at highway speeds, then probably not. But were we to have included more medium-speed roads (long stretches at 45-50 mph) well, possibly.


quote:
Why do you keep saying this? I could go on and on. Nobody has ever got only 30 miles on a full charge in a Model S.


You link to a best-case scenario test, where the car is driven at relatively low speeds constantly to see what the maximum possible range could be. It was not a test that attempted to portray actual driving conditions for a typical person, it was not done in stop-and-go traffic as would be a more realistic experiment for most people.

If you have a 6.0L 450 HP V8 you can also get up to 30 MPG or more doing the same type of driving.

Anything else you want to share with us so that you can continue proving how dumb you are?

quote:
250 full charges? That's at least 50,000 miles on a Model S. Using your own 15 MPG figure for the SUV, that's $13,333 in gas to go the same distance.


50K miles? LOLOL wow, too much stupid contained here. Is that mileage boost coming from adding koolaid to the batteries?

quote:
It's hilarious that you're completely oblivious to how dumb you made yourself look with your posts here.


I'm glad you believe that, but you're experiencing why believing something is inferior to knowing when you are simply outclassed. You are making a pathetic attempt to present EVs as if they are a better choice than their gasoline counterparts and have utterly failed to do so.


RE: Tesla!
By Mint on 4/15/2014 8:15:39 PM , Rating: 2
Really? You're still defending your laughable claim of 30 miles range from 85kWh? In what way does anything you quoted suggest that? It'll fall to 240, maybe 220 miles, not 30.

quote:
You link to a best-case scenario test, where the car is driven at relatively low speeds constantly to see what the maximum possible range could be.
Learn how to read. They got 234 miles WITHOUT much 50-mph driving. It was mostly highway, "cruise control set at 65 mph". They were talking about how to achieve 265 in your quote.

And why did you ignore the second link?
quote:
I was planning to drive fast, from 70 to 75 mph along the Interstates that made up most of the route. The terrain was hilly. There would be a prevailing headwind. And the advancing fall season promised cooler temperatures.

All of these factors would eat into range.
Even then, 168 miles from less than 50kWh. That's over 9x the efficiency of your BS claim.

quote:
50K miles? LOLOL wow, too much stupid contained here.
Figures you'd say that, given that you have the math skills of a 2 year old.

Let me break it down for you: 250 full charges * 200 miles at least per full charge (well below the 265 mile rating and every real world test out there) equals 50,000 miles.

Even Reclaimer, who doesn't agree with me on anything, agrees that you're embarrassingly wrong.


RE: Tesla!
By EricMartello on 4/15/2014 9:31:57 PM , Rating: 2
quote:
Really? You're still defending your laughable claim of 30 miles range from 85kWh? In what way does anything you quoted suggest that? It'll fall to 240, maybe 220 miles, not 30.


You have no clue how electric motors work, no clue how current draw on batteries affects their available capacity and just no clue in general.

You link to an article that sought to test the maximum possible range attainable in IDEAL (read: unrealistic) driving conditions and then think that range applies in all scenarios regardless of the type of driving being done.

You fail to note that on Tesla's own website they indicate that the advertised range assumes a steady speed of ~55 MPH or less, which is a lot lower than the typical 65-80 MPH that traffic flows on just about any highway in America.

Finally, you continue replying, as if you're somehow going to have a "gotcha" moment and show me up. Well, keep trying.

quote:
Learn how to read. They got 234 miles WITHOUT much 50-mph driving. It was mostly highway, "cruise control set at 65 mph". They were talking about how to achieve 265 in your quote.


You should read the crap you link to, but if you know what you are talking about you won't have a need to link to anything. Whether to achieve 234 or 265 miles, they had to drive in very specific conditions close to "optimal".

I can assure you that you will not see anywhere close to 200 miles or more of range in realistic driving conditions, where you will be in traffic, where you will have to merge and pass on the highway, where heat from the road surface and surrounding vehicles will have significant effects on the battery capacity (if you are in slow moving traffic in the summer), and if you live in cold region the capacity issues will come into play.

The fact that you need to sit there and search google and find websites to make your argument for you (and still fail) shows this is a topic that's significantly above your head.

Motortrend and their test results tend to favor those who pay for full page ads in the magazines, so you can rest assured that this tesla mileage test was far from scientific. If they had such a great product it would have sold on its own merit.

MT is the same bunch of idiots who spread that fail idea of high low-end torque being "better than" having an engine with less low-end torque and more peak power. Totally false, but it helped VW sell their 2.slow T engine that they throw into just about ever VW and Audi out there.

quote:
And why did you ignore the second link?


You should consider yourself fortunate that I even bother replying to you at all.

quote:
Even then, 168 miles from less than 50kWh. That's over 9x the efficiency of your BS claim.


Wow, idiot, way to completely misuse the word 'efficiency' while simultaneously showing that you are totally out of your element here.

quote:
Figures you'd say that, given that you have the math skills of a 2 year old.


My attempt at using math that even you could understand has backfired.

quote:
Let me break it down for you: 250 full charges * 200 miles at least per full charge (well below the 265 mile rating and every real world test out there) equals 50,000 miles.


Let me break it down for you: you may have just taken the crown for being the dumbest on this site.

quote:
Even Reclaimer, who doesn't agree with me on anything, agrees that you're embarrassingly wrong.


That's because he doesn't know much about this topic either, but at least he's not making a total buffoon of himself by engaging in a discussion that is exceedingly above his intelligence quotient.


RE: Tesla!
By Mint on 4/15/2014 10:50:43 PM , Rating: 2
Eric, you claim to not like MotorTrend, yet you looked only at that link when I gave you another one of someone who drove 168 miles at 70-75 mph in real world hilly areas using 50kWh of electricity. That's 3.3 miles per kWh.

You claim 30 miles using 85 kWh, i.e. 0.35 miles per kWh. That's one ninth real world measurements.

Even if you were right about slower speed, why don't you explain to me what physics justify a 9x difference in efficiency? Tesla's website notes 55mph for their 300 mile range figure, not 265 or 234. 65-80mph does not need 10x the energy of 55mph, you halfwit.

Misuse the word efficiency? Do I need to link you to the dictionary now? How is miles per kWh not a measure of efficiency?

The battery is temperature controlled, so there is no range degradation from road heat or surrounding vehicles LOL.

You picked a fight with the wrong guy. I'm a Caltech electrical engineering PhD, and my work was even featured in an article here on DT. You clearly are just some poser with no real understanding of engineering or math.

I give links because my facts are based on data. Yours are based on nonsense you conjure in that useless head of yours with no basis in reality.

You're a complete dunce. I won't waste any more time on you.


RE: Tesla!
By EricMartello on 4/16/2014 4:08:32 PM , Rating: 2
quote:
Eric, you claim to not like MotorTrend, yet you looked only at that link when I gave you another one of someone who drove 168 miles at 70-75 mph in real world hilly areas using 50kWh of electricity. That's 3.3 miles per kWh.


You're posting links because you cannot make a competent argument yourself, and the links you posted are not evidence of anything. We do not know the actual conditions of the test, how the car was driven or other factors...and so these things you believe are "evidence" are in fact little more than anecdotes.

quote:
You claim 30 miles using 85 kWh, i.e. 0.35 miles per kWh. That's one ninth real world measurements.


And now your anecdotes have been 'upgraded' to "measurements", funny how that happens.

quote:
Even if you were right about slower speed, why don't you explain to me what physics justify a 9x difference in efficiency? Tesla's website notes 55mph for their 300 mile range figure, not 265 or 234. 65-80mph does not need 10x the energy of 55mph, you halfwit.


This is pretty funny because you fail to acknowledge the fact that air resistance increases exponentially with speed. If you only needed 20 HP to keep the car moving at 60 MPH, and you wanted to go 80 MPH, you would need ~40 HP. You're effectively doubling the power required for only a modest increase in speed due to the way air resistance scales.

While you may be saying "that's not 10x", because you are stupid and fail to accept the fact that as load on batteries increases their AVAILABLE capacity falls. Which means that cruising at 55 MPH may yield a full 85 kW/h worth of power from the batteries, however more than doubling the power drawn by going just 75 MPH means your effective capacity will fall by several kW/h - i.e. the battery depletes at a faster rate.

Let's not forget, at $13 per charge using $0.15 per kWh (which is a low estimate, considering rates in NY and CA are nearly double the national average), that's roughly $0.08 per mile if you manage to get 165 miles on a single charge.

A gasoline car that gets 30 MPG can travel 165 miles on about 5.5 gallons of gas, which at $3.45 per gallon for 'regular' works out to $18.98, or $0.11 per mile. Considering the premium you pay for the tesla (or any other ev), the fact that it's being heavily subsidized by the taxpayer and the fact that gasoline prices have been artificially driven to make "green energy" seem more appealing make it a losing proposition.

quote:
Misuse the word efficiency? Do I need to link you to the dictionary now? How is miles per kWh not a measure of efficiency?


You probably do need to link it because you obviously don't know what it means.

quote:
The battery is temperature controlled, so there is no range degradation from road heat or surrounding vehicles LOL.


Even gasoline cars, which are liquid cooled, are affected by heat soak. To suggest that variance in ambient temperature will not affect the car's performance is laughable.

quote:
You picked a fight with the wrong guy. I'm a Caltech electrical engineering PhD, and my work was even featured in an article here on DT. You clearly are just some poser with no real understanding of engineering or math.


Resorting to "cred dropping" suggests you're getting desperate. If you are really a PhD, you are probably the most pathetic excuse for an "engineer" to have ever been handed a credential.

From making wild claims about the efficacy of electric vehicles to suggesting anecdotal tales are "evidence", to relying on google and wikipedia to post your inane replies...yeah, you're clearly a first-rate engineer.

Now go engineer some coffee and pick up lunch for the office.

quote:
I give links because my facts are based on data. Yours are based on nonsense you conjure in that useless head of yours with no basis in reality.


Hmm, no basis in reality. That's rich coming from a guy who is entirely detached from reality. You have yet to offer any facts, bro.

quote:
You're a complete dunce. I won't waste any more time on you.


The secretary is wondering why it's taking you so long to engineer her latte, and then feature your work on DT. Do a frothy smiley face.


RE: Tesla!
By snhoj on 4/16/2014 7:59:35 PM , Rating: 2
quote:
This is pretty funny because you fail to acknowledge the fact that air resistance increases exponentially with speed. If you only needed 20 HP to keep the car moving at 60 MPH, and you wanted to go 80 MPH, you would need ~40 HP. You're effectively doubling the power required for only a modest increase in speed due to the way air resistance scales.

Aerodynamic drag only makes up about half of the total resistance at 60 MPH in most vehicles with the rest coming from rolling resistance so by my calculation going from 60 to 80 MPH should consume about 39% more power or from 20 HP at 60 MPH to 28 at 80. Considering the Tesla’s very low coefficient of aerodynamic drag and weight it is likely to be less than half of total resistance at 60 MPH making the HP requirement at 80 some what less than 28.

quote:
While you may be saying "that's not 10x", because you are stupid and fail to accept the fact that as load on batteries increases their AVAILABLE capacity falls. Which means that cruising at 55 MPH may yield a full 85 kW/h worth of power from the batteries, however more than doubling the power drawn by going just 75 MPH means your effective capacity will fall by several kW/h - i.e. the battery depletes at a faster rate.

Lithium batteries don't have the high internal impedance of some of the older chemistries. In fact some lithium chemistries have 1/40,000 the internal impedance of lead acid AGM’s for instance. Kokam quoted a 97% charge recovery at 0.3C charge discharge rate for some of their cells. Available capacity won’t decline by anywhere near as much as you imagine. Even in the most demanding condition of say successive sprints to 60 MPH. Initial power demand from stand still would be very low and would rise linearly up to peak power before going into decline. Considering the Tesla’s top speed it might not even see peak power before it reaches 60 MPH. If we say it does then average draw would be around half of peak. At peak power we would be talking about a 3C discharge rate so on average about 1.5C in the sprint. The 3% loss in the Kokam’s at 0.3C represents double the cycle (both charge and discharge) were as we are only interested in the discharge so if scaled linearly 1.5C would produce about a 7.5% loss of available capacity. I know there are some big flaws in the derivation but in the absence of some better figures it gives an idea of what sort of numbers we are talking about. At a normal cruse of say 60 MPH the discharge rate would be less than 0.2C and at 80 it would still be less than 0.25C.


RE: Tesla!
By EricMartello on 4/18/2014 3:34:47 PM , Rating: 1
quote:
Aerodynamic drag only makes up about half of the total resistance at 60 MPH in most vehicles with the rest coming from rolling resistance so by my calculation going from 60 to 80 MPH should consume about 39% more power or from 20 HP at 60 MPH to 28 at 80. Considering the Tesla’s very low coefficient of aerodynamic drag and weight it is likely to be less than half of total resistance at 60 MPH making the HP requirement at 80 some what less than 28.


This is incorrect. As per my example, which is an EXAMPLE to illustrate the exponential increase in air resistance vs speed, if you know how much power it takes to move at a certain speed then you are already accounting for the coefficient of drag. The increase in power would be about the same percentage-wise regardless of the CD, the only difference being that a lower CD would mean less power for a given speed. So your calculation of a 39% power increase is off by a lot.

The model S is not light by any stretch of the imagination; it's a 2-ton porker of a car. Granted there are other luxury sedans tipping the scale near or north of 4,000 lbs - Audi A5 comes to mind - but the Audi has an AWD system which the tesla does not.

quote:
Lithium batteries don't have the high internal impedance of some of the older chemistries. In fact some lithium chemistries have 1/40,000 the internal impedance of lead acid AGM’s for instance. Kokam quoted a 97% charge recovery at 0.3C charge discharge rate for some of their cells.


Lithium batteries are also notoriously "volatile" compared to NiMH, and are still quite toxic (dispelling the whole notion that electric cars are somehow better for the environment). They use a flammable electrolyte that is typically pressurized.

The Tesla 85 kW/h batteries operate at a 400V nominal voltage, which means they have around 212 Ah of capacity. A 0.3C discharge rate on these batteries would equal 64 amps, which is 25.6 kW (34 HP). In the Model S, it would be like driving at a steady 65 MPH on a flat and level surface.

Since the model S is advertised as a performance sedan, to expect people to spend $80K plus on the car and drive it like a granny at slow and steady speeds is unrealistic. Under full acceleration, the discharge rate will be over 850 A, which is 4C. Under hard braking, the batteries will be charged at similarly high rates due to the regenerative braking system. Frequent and high charge/discharge rates can and will reduce effective capacity as well as the useful life of the batteries themselves.

Tesla uses lithium ion batteries, not the more powerful (and lighter) lithium polymer, likely due to the latter being even less stable than the former, and for that particular battery type 4C is pretty much the upper threshold of discharge that you'd want to subject the cells to.

quote:
Available capacity won’t decline by anywhere near as much as you imagine. Even in the most demanding condition of say successive sprints to 60 MPH.


Who pays $80K to occasionally accelerate to 60 MPH and then let off? If you buy a fast car you will tend to drive it harder than you would something like a prius. The cumulative effect, that I explained above, will drastically shorten battery life (long term) as well as the effective capacity (short term).

Unfortunately there are not really any long-term road tests to refer to since the car is so new and not many people have purchased one, but I suspect that in 5-10 years we'll be hearing about battery issues quite frequently...something that Tesla must have anticipated since they are including an 8-year warranty on the batteries.

These are not problems that exist with gasoline or diesel vehicles - and let's remember, electric cars are being billed as better than gas-powered cars. So far there has been nothing put forth to suggest that to be the case. The idea that we need to cut electric cars some slack because they are new does not fly; if they want to gain traction in the market they are really going to have to be a lot better than their competition (and that's WITHOUT subsidies).

quote:
Initial power demand from stand still would be very low and would rise linearly up to peak power before going into decline. Considering the Tesla’s top speed it might not even see peak power before it reaches 60 MPH.


You're missing a key point that you yourself were quick to point out in your first response - electric motors have full torque from 0 RPM. While a motor at 0 RPM is not producing any power, that does not mean it is not consuming energy. When you floor the accelerator in an electric car, the load will be at or near the full capacity of the system.

In the case of the tesla, that means 850+ amps will be drawn from the battery under full throttle, from start and this will taper off as the car slows its acceleration.

quote:
If we say it does then average draw would be around half of peak. At peak power we would be talking about a 3C discharge rate so on average about 1.5C in the sprint.


No, not really. There relationship between output power and input power is quite rigid. You cannot draw less power from the battery and have the motor put out its full rated 310 kW of power. For the motor to put out 310 kW, it will draw MORE than 310 kW from the inverter, which draws from the battery...this works out to about 4C as explained above.

While the motor is drawing full power from the battery and the car is at a stop, that is 0% efficiency. As the motor accelerates the car, the efficiency increases along with speed, topping out at whatever the system efficiency happens to be (always below 100%).

quote:
I know there are some big flaws in the derivation but in the absence of some better figures it gives an idea of what sort of numbers we are talking about. At a normal cruse of say 60 MPH the discharge rate would be less than 0.2C and at 80 it would still be less than 0.25C.


They obviously tuned the cars to have optimal current draws at "average" highway speeds, but this doesn't translate to optimal real-world performance. As I explained in the first paragraph, your estimates on the actual power utilization are on the low side. Mine may seem high but if you run the numbers you will see that they correspond closely to the advertised driving range.

The reality of the situation is that right now electric cars are expensive and inferior to their gasoline counterparts. I would have nothing bad to say about them IF they were allowed to stand ON THEIR OWN merits.

Tesla gets up to $40K or more in taxpayer kickbacks for each car they sell...they cheer on about repaying the loan they got, but they repaid it largely with tax dollars.

GM is really the only automaker that's on taxpayer life support and I no longer purchase GM products because of it. Chrysler did get a bail out which they repaid fully using their own money, and Ford managed to stay solvent without any government assistance.

If electric cars are as great as they're touted to be then people will buy them. It's that simple...


RE: Tesla!
By snhoj on 4/21/2014 9:58:14 PM , Rating: 2

quote:
This is incorrect. As per my example, which is an EXAMPLE to illustrate the exponential increase in air resistance vs speed, if you know how much power it takes to move at a certain speed then you are already accounting for the coefficient of drag. The increase in power would be about the same percentage-wise regardless of the CD, the only difference being that a lower CD would mean less power for a given speed. So your calculation of a 39% power increase is off by a lot.

The model S is not light by any stretch of the imagination; it's a 2-ton porker of a car. Granted there are other luxury sedans tipping the scale near or north of 4,000 lbs - Audi A5 comes to mind - but the Audi has an AWD system which the tesla does not.

When characterizing a vehicles drag you cannot disregard the vehicles rolling resistance which is proportional to the vehicles mass (actually reaction normal to the surface so aero lift or down force will affect it) and doesn’t scale with the squared function of speed.

You misunderstood my reference to the model S weight. Because the car is heavy and has a low Cd I thought rolling resistance would make up a much larger portion of total drag at 60 MPH. I have enough information on the model S to calculate the power consumed over coming aero drag at any given speed.

Fd=1/2*p*v^2*Cd*A, Cd=0.24, A=2.65m^2(estimated), p(mass density of air)=1.225kg/m^3, v=24.44m/s (55MPH)
Fd=232.8N

Power due to drag is force times velocity so
Pd=232.8*24.44=5700W=5.7kW

Total power consumed at 55MPH according to Tesla’s figures is 14.6 kW so if we assume the remainder is solely due to rolling resistance Prr=8.9kW. If we assumed 85% efficiency in the drive Prr would come down to 6.7kW.Note that power consumed by aero drag is substantially less than half total power consumed.

Vehicle weight is 4647lb or 2108kg, Rn=m*g= 2108*9.81=20685N

Prr=Frr*v so Frr=Prr/v=6700/24.44=274.5N

Frr=Crr*Rn so Crr=Frr/Rn =0.01327

Using the more accurate characterization of the vehicle;

P(total,55MPH)=14.6kW, range 320 miles.
Pt(60mph)=17.3kW, run time 4.9hrs, range 294 miles, discharge average 0.2C.
Pt(80mph)=32kW, run time 2.65hrs, range 212 miles, discharge average 0.38C.
Any use of brakes will reduce range. Gasoline contains about 33.6 kWh per gallon. That means the Tesla pack contain the energy equivalent of 2.5 gallons of gasoline. Any way you look at it it is very efficient at converting that energy to miles.

quote:
Tesla uses lithium ion batteries, not the more powerful (and lighter) lithium polymer, likely due to the latter being even less stable than the former, and for that particular battery type 4C is pretty much the upper threshold of discharge that you'd want to subject the cells to.

The size of the battery pack and the number of cells would have been chosen to provide a specific level of performance so yes whatever the maximum discharge rate is will pretty much max out the cells with due consideration to cell life. The key parameter they need to stay below is the core temperature of the cells. Small cells with a small distance between the core center and the outer shell will be able to eject heat at a faster rate than larger cells all helped by active cooling of the cells. Shallower thermal cycling should help cell longevity.
quote:
You're missing a key point that you yourself were quick to point out in your first response - electric motors have full torque from 0 RPM. While a motor at 0 RPM is not producing any power, that does not mean it is not consuming energy. When you floor the accelerator in an electric car, the load will be at or near the full capacity of the system.

In the case of the tesla, that means 850+ amps will be drawn from the battery under full throttle, from start and this will taper off as the car slows its acceleration.


Actually you not totally correct here. The motor controller acts a bit like a transformer while the controller will always see full battery pack voltage on its input side it will chop the voltage on its output side and even when it is pushing its current limit on its output side its input current will be lower. It will not draw the full 850+ amps from the battery from the start. Initial amps on the battery side of the controller will be much lower.
About 98% of the power input comes out the other side but at different voltage and current and in the case of the Tesla inverted to variable frequency 3 phase AC.

quote:
No, not really. There relationship between output power and input power is quite rigid. You cannot draw less power from the battery and have the motor put out its full rated 310 kW of power. For the motor to put out 310 kW, it will draw MORE than 310 kW from the inverter, which draws from the battery...this works out to about 4C as explained above.


You’re talking peaks I’m talking averages. I’m saying that peak power won’t be drawn continuously. Remember peak power is just that a peak that exists in the power curve at some RPM which is not zero. The power curve is approximately a linear ramp from zero to peak. If you want to calculate energy consumed the average power over time is what you want assuming all other factors relate linearly.

quote:
While the motor is drawing full power from the battery and the car is at a stop, that is 0% efficiency.


For about a millisecond. While an ICE is idling that is 0% efficient for much much longer. 0% efficiency at 0 RPM doesn’t tell us a lot about what power will be consumed at that point on the curve.

quote:
The reality of the situation is that right now electric cars are expensive and inferior to their gasoline counterparts.


Expensive yes I don't disagree, inferior or not depends on your use case, on what you are hoping to achieve.


RE: Tesla!
By EricMartello on 4/22/2014 3:58:46 AM , Rating: 2
quote:
When characterizing a vehicles drag you cannot disregard the vehicles rolling resistance


Drag is an aerodynamic effect; rolling resistance is a separate thing, and it's effects on the net friction that the vehicle must overcome to accelerate and move is not substantial. You are driving this conversation off topic by fixating on minutia.

quote:
You misunderstood my reference to the model S weight. Because the car is heavy and has a low Cd I thought rolling resistance would make up a much larger portion of total drag at 60 MPH.


No, I didn't misunderstand you. The fact that the car is heavy contributes to its inefficiency. Rolling resistance is largely a factor of the tires - their width and their inflation pressure.

quote:
Total power consumed at 55MPH according to Tesla’s figures is 14.6 kW so if we assume the remainder is solely due to rolling resistance Prr=8.9kW. If we assumed 85% efficiency in the drive...


You've already made two 'questionable' assumptions in an effort to make the numbers look "good" or seem right...but lets' examine this with your figures.

Going by what you cite as Tesla's 14.6 kW (20 HP) figure to sustain 55 MPH, we can simply scale up the power required for higher speeds, because:

Power:
= Work/Time
= Force x Distance/Time
= Force x Velocity

Air resistance is proportional to the square of the speed, and going from 55 to 80 MPH is a 25 MPH increase, or a 1.46 increase in velocity.

We square 1.46 to get 2.13, which is the new force.

14.6 kW x 1.46 x 2.13 = 45.4 kW

So to drive your model S at 80 MPH using your 14.6 kW @ 55 MPH figure, it takes 45.4 kW or 60 HP - your results are off by quite a bit...at this rate your effective range will be around 150 miles, because remember, 45 kW of engine output will draw MORE than 45 kW from the batteries.

Like I said before, if you know how much power it takes to go a certain speed, you can figure out how much more (or less) you would need for a change in velocity using some very basic math.

quote:
Gasoline contains about 33.6 kWh per gallon. That means the Tesla pack contain the energy equivalent of 2.5 gallons of gasoline. Any way you look at it it is very efficient at converting that energy to miles.


One gallon of gasoline weighs about 6 lbs - a 33.6 kWh lithium ion battery weighs about 75 lbs. Since the vehicle is carrying the weight of the fuel, the energy density of the fuel cannot be overlooked.

Furthermore, charging a battery, assuming a 90% efficiency, means you'd need 1.1C of electricity to do a full charge. 85 kW/h * 1.1 = 93.5 kW/h. You're wasting about 8.5 kW/h per charge, which is like dumping a quarter-gallon of gas on the ground each time you fill up.

Your assertion that the battery pack equals 2.5 gallons of gasoline is only relevant if you operate the car in near-ideal conditions at very conservative speeds. We don't really have much "real world" data that has been accurately documented.

quote:
The key parameter they need to stay below is the core temperature of the cells....Shallower thermal cycling should help cell longevity.


When you're running the cells at their practical limits on a regular basis, you are going to cut their service life down substantially. Regulating the temperature really only contributes to immediate reliability; long term, the effects of high charge/discharge rates stress the physical limits of the batteries themselves...

What else comes with a nearly-decade long warranty? Hyundais and Kias? That says something about reliability.

quote:
The motor controller acts a bit like a transformer while the controller will always see full battery pack voltage on its input side it will chop the voltage on its output side and even when it is pushing its current limit on its output side its input current will be lower.


Stepping up the voltage costs efficiency. I do not know what the operating voltage of the model S inverter happens to be, however I am well aware that it regulates its output voltage which is how it controls engine speed.

quote:
It will not draw the full 850+ amps from the battery from the start. Initial amps on the battery side of the controller will be much lower.


The batteries cannot augment their voltage - they are "fixed" at 400V, which means that in order for the car to put out its peak power the inverter must draw AT LEAST 850A from the battery pack, because:

310 kW = 416 HP = Model S peak power

Amps x Volts = Power
850 x 400 = 340 kW (the 30 kW difference is due to the inverter not being 100% efficient).

When I launch a car, I rev the engine up to a specific RPM and drop the clutch. The engine will stay at or near the launch RPM and then increase. There is nothing that says I cannot launch the car AT the redline if my tires have enough traction, thus having the engine producing almost all of its power AND torque from a stop.

The key point is that the batteries will be discharging at 850A or more when the drive program allows 'full power'...and it will be close to full power from a stop if you floor it and have the car in "performance mode".

quote:
You’re talking peaks I’m talking averages. I’m saying that peak power won’t be drawn continuously.


I'm not really sure what your point is here, because the more power you use within a given time frame the higher the "average" power used will be - fairly obvious. Seems like you're looking for some way to fuzz up the numbers to make electric cars look better than they are.

The reality is that due to the way batteries work, the more power you use with an electric motor, the less your effective battery capacity and so your "net power usage" is going to be a lot more than the peak motor power output.

With gasoline and diesel engines, the efficiency is fairly linear. More power uses more fuel, but the capacity of fuel does not decrease due to operating the engine at a higher power level.

quote:
For about a millisecond. While an ICE is idling that is 0% efficient for much much longer. 0% efficiency at 0 RPM doesn’t tell us a lot about what power will be consumed at that point on the curve.


False. The idling engine is producing torque and therefore power. Simply because the car is not moving does not mean efficiency is 0%.

0% efficiency means that the electric motor is drawing current but not moving, and since it is not moving it is not producing power so efficiency is 0%. When the motor draws current and does not move, the energy radiates as heat. It is not a difficult concept to fathom, even though it is only for a brief moment.

quote:
Expensive yes I don't disagree, inferior or not depends on your use case, on what you are hoping to achieve.


Tesla is trying to achieve an electric car that replaces gasoline cars, and that's just not happening. It takes too long to charge vs filling up with fuel, using the A/C can have a big impact on range, as can loading the car up with passengers and cargo. Reliability is also in question, and there are already plenty of reports from owners who have experienced problems like the car completely shutting off (while being driven) and being unable to start.

What is the selling point of electric cars? Like I said, if you cut out the politics and the fluff backed by the liberal media you really don't have much of anything in favor of electric cars as they are today.


RE: Tesla!
By snhoj on 4/22/2014 8:43:24 PM , Rating: 2

quote:
Drag is an aerodynamic effect; rolling resistance is a separate thing, and it's effects on the net friction that the vehicle must overcome to accelerate and move is not substantial. You are driving this conversation off topic by fixating on minutia.

Really, well all those poor fools buying low rolling resistance tires are just wasting their money then.

quote:
No, I didn't misunderstand you. The fact that the car is heavy contributes to its inefficiency. Rolling resistance is largely a factor of the tires - their width and their inflation pressure.

I bring up the Tesla’s weight and say it will increase rolling resistance, you say no the Tesla is heavy, I say that’s what I meant the Tesla is heavy, you say I didn’t misunderstand you the Tesla is heavy. Even when I agree with you, you have to disagree with me. Yes increasing rolling resistance will make the car less efficient. Yes I understand that rolling resistance is mostly about tires

quote:
You've already made two 'questionable' assumptions in an effort to make the numbers look "good" or seem right...but lets' examine this with your figures.

OK doing it the hard way. Using a published rolling resistance coefficient for a tire similar to what is fitted to the Tesla model S.
“RRC for the Goodyear Eagle GT HR (probably the closest to the RS-A2s) is 0.01217.”
This really quite close to the assumed coefficient calculated at 0.01327. So eliminating my questionable assumptions gives us 6.15 kW consumed by rolling resistance at 55 MPH. Drive efficiency declines to 81.2%. Note this 81.2% accounts for any braking and other energy losses unrelated to drive line efficiency. No questionable assumption left.

quote:
Going by what you cite as Tesla's 14.6 kW (20 HP) figure to sustain 55 MPH, we can simply scale up the power required for higher speeds, because:

Power:
= Work/Time
= Force x Distance/Time
= Force x Velocity

Air resistance is proportional to the square of the speed, and going from 55 to 80 MPH is a 25 MPH increase, or a 1.46 increase in velocity.

We square 1.46 to get 2.13, which is the new force.

The energy consumption of a vehicle virtually all comes back to two factors. Weight and aero drag. First you say weight will make a car inefficient then you totally disregard it in this calculation. So which is it, is weight in or is it out. Does weight generate a drag force which must be overcome or can we say its basically zero so we can just ignore it.

quote:
14.6 kW x 1.46 x 2.13 = 45.4 kW

So to drive your model S at 80 MPH using your 14.6 kW @ 55 MPH figure, it takes 45.4 kW or 60 HP - your results are off by quite a bit...at this rate your effective range will be around 150 miles, because remember, 45 kW of engine output will draw MORE than 45 kW from the batteries.

Like I said before, if you know how much power it takes to go a certain speed, you can figure out how much more (or less) you would need for a change in velocity using some very basic math.

A bit too basic unfortunately. It seems to have escaped your attention that aero drag scales with the cubic function of velocity when it comes to power requirements and including all the drag that doesn’t scale will dramatically exaggerate your figures. I told you exactly what the aero drag power requirements were at 55 MPH yet you choose to ignore that and generate more nonsense. If I apply a bit of reducto ad absurdum to your argument that all drag is aero drag and therefore scales to the square function of velocity then at zero velocity the car would exist in a frictionless state with only its inertia to resist motion if on a level surface. You would have no trouble pushing a 4700lb car with your pinky finger. It only takes a small force and a bit of time to overcome inertia.
quote:
Stepping up the voltage costs efficiency. I do not know what the operating voltage of the model S inverter happens to be, however I am well aware that it regulates its output voltage which is how it controls engine speed.

Actually I’ve been trying to tell you that it regulates its output amperage and it controls motor torque not speed. EV’s would be hard to drive if the motor controller and accelerator position regulated motor speed.
quote:
When I launch a car, I rev the engine up to a specific RPM and drop the clutch. The engine will stay at or near the launch RPM and then increase. There is nothing that says I cannot launch the car AT the redline if my tires have enough traction, thus having the engine producing almost all of its power AND torque from a stop.

EV’s don’t work that way. The power provided at a full throttle launch will ramp from some initial value required to overcome losses up to peak power at peak power RPM and speed.
quote:
The key point is that the batteries will be discharging at 850A or more when the drive program allows 'full power'...and it will be close to full power from a stop if you floor it and have the car in "performance mode".

Wrong. Peak amps is only drawn from the battery at peak power. Peak power occurs around 7000RPM. Peak torque is a band from 0 to7000 RPM. 7000 RPM by my calculation would occur around 57 MPH. Don't forget EV's control torque. You don't get "full power" but full torque when you floor it.

quote:
False. The idling engine is producing torque and therefore power. Simply because the car is not moving does not mean efficiency is 0%.

And that idling torque is totally consumed internally overcoming pumping losses and bearing friction. Energy out /energy in=efficiency. Zero energy out equals zero efficiency. If you happen to have the AC on it might not be completely zero efficiency granted. When it comes to efficiency and cars we can generate efficiency numbers for elements of the car but the car as a whole is a total loss system so what passes for an efficiency measure for the vehicle in totality is actually a rate of consumption.

quote:
0% efficiency means that the electric motor is drawing current but not moving, and since it is not moving it is not producing power so efficiency is 0%. When the motor draws current and does not move, the energy radiates as heat. It is not a difficult concept to fathom, even though it is only for a brief moment.

I didn’t disagree with you.
quote:
Tesla is trying to achieve an electric car that replaces gasoline cars, and that's just not happening. It takes too long to charge vs filling up with fuel, using the A/C can have a big impact on range, as can loading the car up with passengers and cargo. Reliability is also in question, and there are already plenty of reports from owners who have experienced problems like the car completely shutting off (while being driven) and being unable to start.


Actually I was thinking more about what their customers were hoping to achieve. Personally I would like to get off blood oil.


RE: Tesla!
By EricMartello on 5/3/2014 1:08:35 AM , Rating: 2
quote:
Really, well all those poor fools buying low rolling resistance tires are just wasting their money then.


Pretty much, and they're sacrificing handling and braking ability for a negligible "improvement" in fuel efficiency.

quote:
The energy consumption of a vehicle virtually all comes back to two factors. Weight and aero drag. First you say weight will make a car inefficient then you totally disregard it in this calculation. So which is it, is weight in or is it out. Does weight generate a drag force which must be overcome or can we say its basically zero so we can just ignore it.


I didn't disregard weight. Weight has already been accounted for by the baseline value, which I scaled.

It's really very simple and I'll repeat it for you: if we know how much power it takes for a vehicle to move at a certain speed on a level surface, we can use a simple scaling formula to ascertain the power required at higher or lower speeds.

quote:
A bit too basic unfortunately. It seems to have escaped your attention that aero drag scales with the cubic function of velocity when it comes to power requirements and including all the drag that doesn’t scale will dramatically exaggerate your figures.


False. The primary resisting force is aerodynamic drag. Again, your fixation on minutia in an effort to obfuscate the real point only makes you look like someone who can't accept that they were wrong.

quote:
I told you exactly what the aero drag power requirements were at 55 MPH yet you choose to ignore that and generate more nonsense. If I apply a bit of reducto ad absurdum to your argument that all drag is aero drag and therefore scales to the square function of velocity then at zero velocity the car would exist in a frictionless state with only its inertia to resist motion if on a level surface. You would have no trouble pushing a 4700lb car with your pinky finger. It only takes a small force and a bit of time to overcome inertia.


Verbal diarrhea is not the mark of someone who knows what they're talking about. You seem to be sliding into a pit of repetition peppered with stupidity. Next thing we'll have you telling us that climate change affects the tesla's efficiency because vegetable.

quote:
Actually I’ve been trying to tell you that it regulates its output amperage and it controls motor torque not speed. EV’s would be hard to drive if the motor controller and accelerator position regulated motor speed.


That's incorrect. It uses a PWM type of speed control, which limits voltage. Current limiting is an automatic result of pulsing the drive voltage at lower frequencies when the car is moving at lower speeds, and higher frequencies when the car is moving faster. The pwm system allows for "real time" feedback on what the engine is doing and allows its performance and response to be tuned. If you were to simply make a direct "always on" connection to the motor from the inverter, the car would probably have trouble gaining traction.

FYI direct current limiting causes the excess current to be bled off as heat. That would be a very inefficient method of regulating the engine speed...and incidentally it's why tesla uses a PWM speed control. And yes, it's called a SPEED CONTROL not a torque control.

quote:
EV’s don’t work that way. The power provided at a full throttle launch will ramp from some initial value required to overcome losses up to peak power at peak power RPM and speed.


I'm quite aware of the differences; but you've cleverly managed to miss my point yet again. The point I was making, is that while electric cars may have "full torque" from 0 RPM, launching a gasoline car from a stop can be done in such a way that you have nearly full power and torque from a stop. It's called launching for a reason.

Since the inverter regulates the motor using a PWM type of system, full throttle doesn't equal a full-on connection between the motor and power source. The entire powerband is regulated, and that means the power is always pulsed, i.e. on and off.

quote:
Wrong. Peak amps is only drawn from the battery at peak power. Peak power occurs around 7000RPM. Peak torque is a band from 0 to7000 RPM. 7000 RPM by my calculation would occur around 57 MPH. Don't forget EV's control torque. You don't get "full power" but full torque when you floor it.


The problem with people like you is that you believe you know what you're talking about but don't. Do you think that the motor spinning at 7,000 RPM in free air (no load) will draw the same current as it would pushing the weight of the car down a drag strip (full load)?

The amount of current drawn is inversely proportional to the delta between the no-load speed of the motor and the motor speed reduction when a is load placed on said motor.

What does that mean?

When there is NO LOAD on the motor, it is spinning at it's full RPM based on whatever the input voltage is and the current drawn is minimal.

When there is a load on the motor, the motor speed drops which causes the voltage to drop. The motor draws more current as it attempts to accelerate to its no-load RPM, or to a point that matches its input voltage.

Please shut up about your idiotic and incorrect calculations and moronic theories about how electric motor drive systems work. You really do not know what you are talking about here and it's just getting tedious repeating myself.

quote:
And that idling torque is totally consumed internally overcoming pumping losses and bearing friction.


The amount of power consumed by the belt driven accessories is minimal at idle. Torque is not consumed; it is transferred.

quote:
Actually I was thinking more about what their customers were hoping to achieve. Personally I would like to get off blood oil.


Blood oil? Yeah, I'm not surprised you'd believe in something as retarded as that.

You should be more concerned with your liberalism infection and the fact that it is steadily making you dumber. Have you considered just staying home all the time, thus eliminating the need for a vehicle altogether?


RE: Tesla!
By snhoj on 5/7/2014 8:14:22 PM , Rating: 2
quote:
I didn't disregard weight.

Oh yes you did. I for one happen to understand that zero squared is still zero.

quote:
Weight has already been accounted for by the baseline value, which I scaled.

Yes but you than scale it with total disregard of weight solely as a function of speed.

quote:
It's really very simple and I'll repeat it for you: if we know how much power it takes for a vehicle to move at a certain speed on a level surface, we can use a simple scaling formula to ascertain the power required at higher or lower speeds.

Repeating the same flawed argument over and over again doesn’t make it correct.

quote:
False. The primary resisting force is aerodynamic drag. Again, your fixation on minutia in an effort to obfuscate the real point only makes you look like someone who can't accept that they were wrong.

I don’t accept I’m wrong because I’m not and I have proved it. Minutia it’s not. Have you ever tried to push a 4700lb vehicle?

quote:
Verbal diarrhea is not the mark of someone who knows what they're talking about. You seem to be sliding into a pit of repetition peppered with stupidity. Next thing we'll have you telling us that climate change affects the Tesla's efficiency because vegetable.

I see name calling and personal attacks but I don’t see an argument. I guess you lost that one.

quote:
That's incorrect. It uses a PWM type of speed control, which limits voltage. Current limiting is an automatic result of pulsing the drive voltage at lower frequencies when the car is moving at lower speeds, and higher frequencies when the car is moving faster. The pwm system allows for "real time" feedback on what the engine is doing and allows its performance and response to be tuned.

If you can measure it you can control a system according to it.

quote:
If you were to simply make a direct "always on" connection to the motor from the inverter, the car would probably have trouble gaining traction.

I never said anything about always on.

quote:
FYI direct current limiting causes the excess current to be bled off as heat. That would be a very inefficient method of regulating the engine speed...and incidentally it's why tesla uses a PWM speed control. And yes, it's called a SPEED CONTROL not a torque control.

Who said anything about current limiting with an additional load? The Back EMF of the motor and the resistance of the windings can be used to control the current if you chop the voltage accordingly. I find it really hard to believe that you think you cannot control the torque output of a motor. Really?

quote:
I'm quite aware of the differences; but you've cleverly managed to miss my point yet again. The point I was making, is that while electric cars may have "full torque" from 0 RPM, launching a gasoline car from a stop can be done in such a way that you have nearly full power and torque from a stop. It's called launching for a reason.

I didn’t miss the point. The point was redundant. Just because you can have full power and massive torque and convert your tires to smoke at launch doesn’t mean that EV’s must have full power available at launch. They don’t and they don’t need to unless the objective is to make lots of expensive smoke.

quote:
Since the inverter regulates the motor using a PWM type of system, full throttle doesn't equal a full-on connection between the motor and power source. The entire powerband is regulated, and that means the power is always pulsed, i.e. on and off.

Yes, with the notable exception of exactly at peak power but only for DC systems.

quote:
The problem with people like you is that you believe you know what you're talking about but don't. Do you think that the motor spinning at 7,000 RPM in free air (no load) will draw the same current as it would pushing the weight of the car down a drag strip (full load)?

WTF. Of course not. Where are you getting this stuff from?

quote:
Please shut up about your idiotic and incorrect calculations and moronic theories about how electric motor drive systems work. You really do not know what you are talking about here and it's just getting tedious repeating myself.

When you get abusive do people pay more attention to what you say? Does it improve your credibility?

quote:
The amount of power consumed by the belt driven accessories is minimal at idle. Torque is not consumed; it is transferred.

When a system is in equilibrium, i.e. idling at a constant RPM, any torque produced by the engine must be matched by an equal and opposite torque or the engine would not be in a state of equilibrium and would either be accelerating or decelerating. When the drive is disengaged that torque will be predominantly internal losses. Physics 101. I’d be interested to hear your take on where that torque is being transferred to.


RE: Tesla!
By EricMartello on 5/10/2014 12:49:57 AM , Rating: 1
quote:
Oh yes you did. I for one happen to understand that zero squared is still zero.


If you are calculating the approximate power required for a car to move at a certain speed without knowing the power required to move at ANY speed in the first place, then weight would be part of that equation...but since we already knew how much power it takes to move the car at a given speed, weight has already been factored, and therefore we can scale power, as I did. Not sure how many times I have to repeat this until you get it.

quote:
Yes but you than scale it with total disregard of weight solely as a function of speed.


No, I did not. WEIGHT WAS ALREADY FACTORED IN TO DETERMINE THE BASE VALUE OF POWER REQUIRED TO TRAVEL 55 MPH. The car does not get heavier if it moves at a faster speed; the only thing that changes is the wind resistance.

You're really obsessing over nothing when your claims of superior efficiency have already been dispelled, so get over it and learn some basic math while you're at it.

quote:
Repeating the same flawed argument over and over again doesn’t make it correct.


And yet here you are, posting again, still wrong.

quote:
I don’t accept I’m wrong because I’m not and I have proved it. Minutia it’s not. Have you ever tried to push a 4700lb vehicle?


The only thing you've proven is that you flunked high school physics class, and even with your constant referencing of google and wikipedia, you still can't get it right. Have you ever pushed a car that weighs 2,000 LBS at 40 MPH and 4,000 LBS at 80 MPH? L...O...L

quote:
Who said anything about current limiting with an additional load? The Back EMF of the motor and the resistance of the windings can be used to control the current if you chop the voltage accordingly. I find it really hard to believe that you think you cannot control the torque output of a motor. Really?


Oh that's a new one - you restate things I've said and then try to present it as what you've been saying all along. LOL Nice job, but you are still not grasping the basic functions of an electric motor and its respective speed controller.

In the context of an electric motor, VOLTAGE is adjust to control the engine speed. A turning motor is producing power, which INCLUDES torque...however you incorrectly continue to refer to the speed controller as a torque modulator, and even suggest that the motor speed is regulated by limiting current to the engine when increasing/decreasing voltage is all that's necessary.

quote:
I didn’t miss the point. The point was redundant. Just because you can have full power and massive torque and convert your tires to smoke at launch doesn’t mean that EV’s must have full power available at launch. They don’t and they don’t need to unless the objective is to make lots of expensive smoke.


Actually it's not redundant, because it completely shatters the whole "full torque from zero RPM" line that the ignorant EV humpers cite as a major benefit of electric motors over gasoline engines...apparently they don't know how to launch a gasoline car to maximize its acceleration and assume that all acceleration happens off-idle...and if you launch correctly your tires will hook and you will accelerate quite nicely.

quote:
When you get abusive do people pay more attention to what you say? Does it improve your credibility?


I'm hardly being abusive...maybe you're just too whiny and thin-skinned.

quote:
When a system is in equilibrium, i.e. idling at a constant RPM, any torque produced by the engine must be matched by an equal and opposite torque or the engine would not be in a state of equilibrium and would either be accelerating or decelerating. When the drive is disengaged that torque will be predominantly internal losses. Physics 101. I’d be interested to hear your take on where that torque is being transferred to.


You probably spent hours writing this statement, even soliciting your asian friends for help, only to end up "not getting it".

Your previous statement attempted to portray the engine accessories as requiring all or most of the torque of the engine at idle - which is false. The power steering pump, the water pump, alternator and A/C unit combined place a relatively minor parasitic load on the engine, whether it's idling or at its redline.

Yes, I'm sure you thought you are brilliant for pointing out newton's 3rd law, but that is obvious that was never in question or in doubt.

Torque is a force, so it is transferred rotationally along an axis. It is not "consumed". Power is consumed, and power is torque x RPM.

An axle spinning at a certain RPM being driven with a fixed amount of torque can continue turning so long as the load placed on the axle does not exceed the amount of torque which is driving it...however if you increase the load on the axle without increasing the torque, the RPM will decline. Get it? That is power being consumed - the torque does not change.

Go back to school.


RE: Tesla!
By snhoj on 5/11/2014 7:03:13 PM , Rating: 2
quote:
If you are calculating the approximate power required for a car to move at a certain speed without knowing the power required to move at ANY speed in the first place, then weight would be part of that equation...but since we already knew how much power it takes to move the car at a given speed, weight has already been factored, and therefore we can scale power, as I did. Not sure how many times I have to repeat this until you get it.

Because weight doesn’t change with speed, the drag force due to weight doesn’t change with speed. Therefore the power consumed due to weight scales linearly with velocity or is proportional to mass times velocity. The drag force due to aero drag scales with the square of velocity. Therefore the power consumed due to velocity (aero drag) scales with the cube of speed or is proportional to velocity cubed. Adding the results of the linear function and the cube function creates a third function in which mass and velocity still feature separately. That third function is NOT proportional to the square of speed. Mass times velocity is NOT a constant and so cannot be factored out along with the other constants when figuring out proportionality. I’m not wrong about this.
quote:
so get over it and learn some basic math while you're at it.

quote:
quote:
Minutia it’s not. Have you ever tried to push a 4700lb vehicle?


That went straight over your head. The Tesla’s weight and tires will result in a rolling resistance of 56lb force. If you think that is insignificant to the point of being practically zero when compared to aero drag then what else can I say. Either you can’t understand or you won’t understand and neither of these makes you look good.

quote:
Oh that's a new one - you restate things I've said and then try to present it as what you've been saying all along. LOL Nice job, but you are still not grasping the basic functions of an electric motor and its respective speed controller.

An EV is not like one of your model aircraft and the correct terminology is Motor controller specifically so people like you won’t become confused. I posted this on the 4/16/2014 in this thread so it is what I have been saying all long.
quote:
In an EV we don't want to control the speed of the motor but the torque it puts out. If the accelerator position controlled speed the vehicle would be very difficult to drive. Hence the motor controller manipulates the current by manipulating the voltage but the voltage doesn't bear any direct relationship to the accelerator position. None of this is in disagreement with what you have said I’m just trying to add a different perspective. As for load when you encounter a hill the driver must adjust the accelerator pedal to maintain speed (as you currently do in your ICE powered car) increasing the current to maintain the voltage.


quote:
Actually it's not redundant, because it completely shatters the whole "full torque from zero RPM" line that the ignorant EV humpers cite as a major benefit of electric motors over gasoline engines...apparently they don't know how to launch a gasoline car to maximize its acceleration and assume that all acceleration happens off-idle...and if you launch correctly your tires will hook and you will accelerate quite nicely.

The advantage of full torque from zero is not having to have a clutch (or torque converter).The advantage is not having to have a clutch. It’s a mechanical simplification. In the case of Tesla the range of the motor is so broad that it also doesn’t need a gearbox and can make do with a single reduction ratio. A further mechanical simplification. The net result of this is lower weight better reliability and reduced cost.

quote:
I'm hardly being abusive...maybe you're just too whiny and thin-skinned.

Denial followed by more abuse. That’s funny LOL.

quote:
You probably spent hours writing this statement, even soliciting your asian friends for help, only to end up "not getting it".

Your previous statement attempted to portray the engine accessories as requiring all or most of the torque of the engine at idle - which is false. The power steering pump, the water pump, alternator and A/C unit combined place a relatively minor parasitic load on the engine, whether it's idling or at its redline.

Yes, I'm sure you thought you are brilliant for pointing out newton's 3rd law, but that is obvious that was never in question or in doubt.

Torque is a force, so it is transferred rotationally along an axis. It is not "consumed". Power is consumed, and power is torque x RPM.


So if torque is not consumed and power is consumed and power is torque x RPM then really it is just RPM that is being consumed?? LOL. You’re funny.

quote:
An axle spinning at a certain RPM being driven with a fixed amount of torque can continue turning so long as the load placed on the axle does not exceed the amount of torque which is driving it...however if you increase the load on the axle without increasing the torque, the RPM will decline. Get it? That is power being consumed - the torque does not change.

Go back to school.


All that and you still haven’t said were torque in an idling engine is being transferred to.

How does it feel Eric being bested by a “dim-witted buffoon”. Nothing in this world is free Eric not even cheap shots.


RE: Tesla!
By EricMartello on 5/15/2014 1:55:58 AM , Rating: 1
quote:
Because weight doesn’t change with speed, the drag force due to weight doesn’t change with speed.


Repeating what I said...brilliant, you're learning that you can be right more often if you just repeat what I say.

quote:
Therefore the power consumed due to weight scales linearly with velocity or is proportional to mass times velocity.


But then you decide to be a liberal, keep talking, and be wrong again when you could have just shut up and spared yourself further humiliation.

Let's talk about this thing called MOMENTUM. The weight of a vehicle at speed does not change, and if you are traveling at a constant velocity YOU ARE NOT ACCELERATING and therefore the effects of mass do not change.

Yes, it takes more power to accelerate a larger mass to a certain speed BUT once at speed, and that's what we're talking about here in case you totally missed it, there is no difference in power required to move the object due to mass.

The PRIMARY resisting force is wind resistance when traveling at a higher speed. That...is...all.

quote:
The drag force due to aero drag scales with the square of velocity. Therefore the power consumed due to velocity (aero drag) scales with the cube of speed or is proportional to velocity cubed.


Funny, this guy lost the battle, the audience went home but he's still so sure he's right. Then he says this and proves that he still doesn't get it.

quote:
Adding the results of the linear function and the cube function creates a third function in which mass and velocity still feature separately. That third function is NOT proportional to the square of speed. Mass times velocity is NOT a constant and so cannot be factored out along with the other constants when figuring out proportionality. I’m not wrong about this.


Oh, you are terribly wrong and if you think you're not then you are fitting the very definition of stupid.

We are talking about a constant velocity, not a change in velocity (acceleration). Mass doesn't change due to speed, and once a mass is moving it has this thing called momentum.

Momentum, in the case of a moving car, is effectively a constant that will scale linearly with velocity - and that makes sense because like I told you before, the car weighs exactly the same at 55 MPH as it does at 80 MPH.

The power requirements I provided to you are accurate...period...and more importantly, you were wrong altogether about EVs being more efficient so trying to make your "last stand" here and failing isn't doing you any favors.

quote:
That went straight over your head. The Tesla’s weight and tires will result in a rolling resistance of 56lb force. If you think that is insignificant to the point of being practically zero when compared to aero drag then what else can I say. Either you can’t understand or you won’t understand and neither of these makes you look good.


No, I simply disregard irrelevant statements such as this one...but keep talking about rolling resistance, man...like you even know what that is. It's really helping you get your point across, except your point that EVs are "more efficient" than their gasoline counterparts is a myth I've already dispelled so what exactly are you hoping to accomplish by continuing to display how poorly you understand physics?

quote:
An EV is not like one of your model aircraft and the correct terminology is Motor controller specifically so people like you won’t become confused. I posted this on the 4/16/2014 in this thread so it is what I have been saying all long.


EVs are virtually identical to model RC cars and planes, save for the Tesla using an AC motor while the models use DC motors and do not require an inverter.

You could call a speed controller a "motor controller" just like you could call a woman a "dame", but just like calling a woman a dame suggests you have no clue how to deal with women...referring to a speed controller as a "motor controller" suggests you have no clue about electric drive systems.

quote:
The advantage of full torque from zero is not having to have a clutch (or torque converter).The advantage is not having to have a clutch. It’s a mechanical simplification.


In terms of driving performance its really not an "advantage" in any way, shape or form. It's just a mechanical necessity, because there is no reason to idle an electric motor.

quote:
In the case of Tesla the range of the motor is so broad that it also doesn’t need a gearbox and can make do with a single reduction ratio. A further mechanical simplification. The net result of this is lower weight better reliability and reduced cost.


A direct drive is one of the perks of using an electric drive system, but I've demonstrated that it's a stretch to say that it is "better". As far as being more reliable? Maybe, maybe not. The motor itself is probably not going to break down but the complex electronics that make it run are prone to failure.

So you have a more reliable transmission but you introduce potentially thousands of potential failure points with each additional line of code and electronic component required to make the car work.

Net effect? No improvement over a modern gasoline car in this dept either.

quote:
So if torque is not consumed and power is consumed and power is torque x RPM then really it is just RPM that is being consumed?? LOL. You’re funny.


If an engine produces a constant 100 ft-lbs of torque and the no-load engine speed is 1,000 RPM, adding a load that reduces the RPM by 500 is equivalent to a 50% drop in power. Note that the input torque remains unchanged, hence it is not being "consumed".

(1,000 RPM x 100 ft-lbs) / 5252 = 19.04 HP (no-load)
(500 RPM x 100 ft-lbs) / 5252 = 9.52 HP (50% load)

It's funny that you cannot grasp this concept and yet feel compelled to continue replying. I almost feel like you're being wrong on purpose because you want me to educate you.

quote:
All that and you still haven’t said were torque in an idling engine is being transferred to.


Torque is transferred to anything that is connected to the output shaft of the engine. Why are you struggling with these kiddie concepts?

quote:
How does it feel Eric being bested by a “dim-witted buffoon”. Nothing in this world is free Eric not even cheap shots.


Really, or is this a segue into your comedy routine? LOL


RE: Tesla!
By EricMartello on 4/22/2014 5:48:07 PM , Rating: 2
One thing worth adding to this discussion is the efficiency of electrical generation. In the US most electricity is generated by coal-fired plants, followed by nuclear.

Here's a brief rundown of electrical generation efficiency by power plant type:

Recirculated Natural Gas Turbine - up to 58%
Coal Steam Turbine - 39-47%
Standard Natural Gas Turbine - up to 39%
Fuel-Oil Steam Turbine - 38-44%
Wind Turbine - up to 35%
Nuclear (Fission) - 33-36%
Geothermal - 15%
Solar - up to 15%

Based on America's typical power plant type (coal), you're getting about 40% efficiency in generation, while 60% is waste heat.

For you to get 1 kW/h out of your outlet, 2.5 kW/h of electricity must be generated, PLUS there are transmission losses which are in the 6% range on average in the US, meaning that the power company must generate 2.7 kW/h from the power company when you use 1 kW/h.

So knowing this, charging your 85 kW/h battery pack assuming a 90% efficiency means 94 kW/h. Since each kW/h you use requires 2.7 kW/h to be generated, you are effectively using 254 kW/h to charge the battery pack.

This works out to a net efficiency of about 1 kW/h per mile.

It takes about 5 kW/h to refine a gallon of petroleum into gasoline. If you add this to the 33.6 kW/h figure, you have 38.6 kW/h of energy for a gallon of gasoline.

At 30 miles per gallon, you're using 1.29 kW/h per mile...but there are plenty of gasoline-driven cars that can do 40 MPG, which brings it down to 0.97 kW/h per mile.

The point I'm making here is that when the entire "chain" of energy is considered, you are really not doing any better with the electric car than you are with the gas car - and the gas car is far more practical.

Side Note:
------------
The US has an abundance of natural gas, yet obama and liberals constantly try to oppose efforts to access this gas, siding with environmental wackos that love making baseless, unscientific claims.

A recirculated NG plant is one of the most efficient ways to generate electricity. If fracking was "unleashed" in America, it would create thousands of jobs while simultaneously lowering energy costs across the board. It would also reduce the emissions that are often cited as being harmful (although there is no evidence to support this claim).

All that talk about "sustainability" and "energy independence" coming from anyone on the left is a load of horsesh1t - they're more fixated on fake problems like global warming and profiting from carbon emissions.


RE: Tesla!
By snhoj on 4/22/2014 9:29:55 PM , Rating: 2
America is well advanced in its natural gas production. In fact so much development went on that they had a gas surplus and gas prices fell to about a third of production costs. I don't need to tell you that is not sustainable. Market forces not greenies have intervened and prices are rising to more sustainable levels. Cheap gas is why virtually all new generation capacity is natural gas plants. Coal is on the decline. It now makes up just 43% of total generation in the US. It wasn't long ago it was 50%. It peaked in 2007. concern over the generation mix is why a lot of EV owners also have grid tied solar systems installed. Where I live we have around 70% hydro electric generation. Australia has around 80% coal generation. Its a good thing to consider.
I wouldn't underestimate the benefits of energy independence to the US. It will improve the balance of trade and reduce the need to borrow. The US spends a lot on energy security not just in dollars but also in lives.


RE: Tesla!
By snhoj on 4/23/2014 5:10:25 PM , Rating: 2
The whole balance of trade situation could be to blame for the global financial crisis (GFC). The USA buys more goods from China than it sells to China. China winds up with a surplus of Trillions US dollars. China wants to put that money to work so it lends it back to the US. The banks are awash with cheap money that they need to lend out so they get reckless with their lending practices and a huge property bubble grows bigger and bigger over a few years. When the bubble bursts as all bubbles must at some point some banks fail others need rescuing and the whole financial system looks like it might collapse. So no one will lend to anyone else and now we have a credit squeeze and the GFC goes into overdrive. An enormous amount of wealth is destroyed around the world. The question I ask is what is different now?


RE: Tesla!
By EricMartello on 5/3/2014 1:21:57 AM , Rating: 2
We're not talking about economics, skippy, the point was that electric power generation is inherently inefficient...and the fact that you totally veered off topic is basically you conceding that I PWNED your pathetic liberal arguments in favor of electric cars.

While an electric motor does a great job of converting electrical energy into mechanical work, when you consider the fact that the the fuel consumed to generate said electricity is far greater than the energy wasted by gasoline and diesel engines as heat, we can clearly see the SCAM that is being perpetuated by the whole "green energy" political agenda.

Coal is an abundant resource; it's on the 'decline' because of a concerted effort by the EPA to snuff it out, forcing expensive, impractical and unreliable "green energy" on Americans. It all fits into the broader left-wing agenda of deception, the notion that "climate change" is caused by human activity and supported by dim-witted buffoons like yourself, who fail to realize that being educated today is more of a liability than an asset.

You did better than most liberals do in your attempt to make a technical case for electric cars, but the facts are not on your side and your understanding of the mechanics of electric cars is quite obviously limited.

Your complete dodge to the fact that electricity generation is grossly LESS EFFICIENT than the energy consumed end-to-end by gasoline and diesel fueled vehicles only serves to prove my point.


RE: Tesla!
By snhoj on 5/8/2014 6:18:48 PM , Rating: 2
quote:
We're not talking about economics, skippy, the point was that electric power generation is inherently inefficient...and the fact that you totally veered off topic is basically you conceding that I PWNED your pathetic liberal arguments in favor of electric cars.

I just find efficiency of generation secondary to anything that has real world effects. Carbon intensity changes with fuel type as does economics or cost per unit. So efficiency should really only be considered within a single fuel type unless you apply some sort of compensating factor. Carbon intensity only matters if you buy into anthropogenic global warming. You've made your position on that very clear. That really just leaves economics and that changes with fuel type. So you can "PWN" it if you like I’m just not that interested.

By the way you did bring up energy independence in your side bar. Electric car = 100% US sourced energy, ICE age car = 30% US sourced energy, 70% imported energy. +1 for the EV

quote:
While an electric motor does a great job of converting electrical energy into mechanical work, when you consider the fact that the the fuel consumed to generate said electricity is far greater than the energy wasted by gasoline and diesel engines as heat, we can clearly see the SCAM that is being perpetuated by the whole "green energy" political agenda.

Like I said where I live 70% hydroelectric generation. No fuel consumed there just falling water. Most of this generating capacity was built prior to environmentalism becoming fashionable. No green agenda involved. No tax breaks for EV's here either.

quote:
It all fits into the broader left-wing agenda of deception, the notion that "climate change" is caused by human activity and supported by dim-witted buffoons like yourself, who fail to realize that being educated today is more of a liability than an asset.

Oh WOW, just WOW. So education and the educated are the enemy. I guess that means ignorance is an asset.

Abusive name calling and personal attacks add nothing to the debate and really only serves to depreciate your cause. People usually resort to this behavior because they have lost the rational argument and are basically trying to create an emotional fist fight where they try to wound with words rather than admitting defeat. When you start calling me a dim-witted buffoon for occupying a position I haven’t well that shot misses the mark by a mile. While I can admire a never say die atitude I do read these outbursts as victory.


RE: Tesla!
By EricMartello on 5/10/2014 12:04:16 AM , Rating: 1
quote:
I just find efficiency of generation secondary to anything that has real world effects.


Good for you, but you are still wrong. The fact that electricity must be generated means that using it as the power source for commuter vehicles is just a bad idea...at least until we have something like cold fusion along with high energy density batteries.

quote:
So efficiency should really only be considered within a single fuel type unless you apply some sort of compensating factor.


You have to exclude the inconvenient fact that electricity generation is inherently inefficient and causes more pollution in order for your "green" political agenda about electric cars seem "plausible".

The bottom line is that it's still a lot better overall to stick with refined petroleum - aka gasoline.

BTW, the 5 kW/h figure to refine a gallon of gasoline from petroleum also includes a by-product known as diesel. When you consider that for every gallon of gasoline, a portion of that becomes diesel fuel without any additional effort, it further enhances the end-to-end efficiency of gasoline and diesel as a choice fuel for vehicles.

quote:
By the way you did bring up energy independence in your side bar. Electric car = 100% US sourced energy, ICE age car = 30% US sourced energy, 70% imported energy. +1 for the EV


Falsorama. Fuels are sold as commodities on a global market. The refiners who operate in the Gulf of Mexico do not sell directly to the US, they sell to the highest bidder.

The differences in fuel prices by country are largely due to the taxes that are levied on the fuel by the respective governments, as well as any tariffs that may be imposed. For example, low-grade "industrial" diesel is taxed at a substantially lower rate than vehicle-grade diesel in europe, and so it costs less per gallon. That's why the liberal dystopia that we call europe pays out the a55 for fuel while Americans enjoy relatively low and stable prices.

The idea that we're 'on the verge of running out' of fossil fuels is a baseless claim with no supporting evidence. That said, I do agree that we should find renewable fuel sources - but not at the behest of a government mandate and not according to what some eco-zealots believe.

quote:
Like I said where I live 70% hydroelectric generation. No fuel consumed there just falling water. Most of this generating capacity was built prior to environmentalism becoming fashionable. No green agenda involved. No tax breaks for EV's here either.


Guess what, that's irrelevant because your particular situation does not represent the average worldwide situation for electric energy generation. Hydroelectric power is great when you have the proper natural features to construct such a plant, but as a percentage of all electricity generated, hydro power is not that much.

Most electricity is generated by burning a fuel, and the average efficiency is in the low 40% range as previously stated.

quote:
Oh WOW, just WOW. So education and the educated are the enemy. I guess that means ignorance is an asset.


You need to stop referring to being blindly indoctrinated, relieved of independent thought, as being "educated". Your ignorance stems from your misguided belief that education somehow replaces the need to think and form your own ideas, even if said ideas run contrary to the consensus.

quote:
Abusive name calling and personal attacks add nothing to the debate and really only serves to depreciate your cause.


I'm not a liberal and therefore I have no "cause". My interest is ensuring that the information provided about a given topic is accurate and objective. As I said before, if electric cars were better than their gasoline counterparts I would gladly state that in support of them - but they are not, and I've clearly explained why.

quote:
People usually resort to this behavior because they have lost the rational argument and are basically trying to create an emotional fist fight where they try to wound with words rather than admitting defeat.


The readers can decide for themselves who defeated whom...by my count every one of your claims and points of contention has been thoroughly debunked.

quote:
When you start calling me a dim-witted buffoon for occupying a position I haven’t well that shot misses the mark by a mile. While I can admire a never say die atitude I do read these outbursts as victory.


You are dim-witted for attempting to shift the topic from the "real" energy efficiency of electric cars to some economic nonsense after I pointed out how inefficient electric cars are due to electrical power generation and its limitations...that was you raising the flag of defeat, followed by me gloating.


RE: Tesla!
By snhoj on 5/11/2014 8:34:18 PM , Rating: 2
quote:
You have to exclude the inconvenient fact that electricity generation is inherently inefficient

Efficiency is not an end in itself but a means to another end. Its good EV’s are efficient because their batteries can be smaller and because they use electricity that someone has to pay for but that is where it stops at the plug.

Thank you for playing.


RE: Tesla!
By EricMartello on 5/15/2014 1:00:41 AM , Rating: 2
quote:
Efficiency is not an end in itself but a means to another end. Its good EV’s are efficient because their batteries can be smaller and because they use electricity that someone has to pay for but that is where it stops at the plug.


The entire push behind EVs - including tax subsidies and CAFE standards that place unrealistic fuel efficiency burdens on automakers - are billed as being "more efficient and better for the economy".

I showed you why EVs are actually LESS efficient, and made you look quite stupid in the process. Oh, and I appreciate the irony in the way that the CAFE standards put forth by the EPA, which were meant to be "unattainable", resulted in automakers producing super-efficient gasoline cars that solidify the terrible idea that EVs are with our current method of electricity generation.

quote:
Thank you for playing.


Oh, the game ended several posts ago when you got PWNED by facts and were left with nothing but a complete topic shift (which failed).

Your continued attempts to save face just aren't working out for you...because you are on the wrong side of this argument and politics.


"The whole principle [of censorship] is wrong. It's like demanding that grown men live on skim milk because the baby can't have steak." -- Robert Heinlein














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