backtop


Print 102 comment(s) - last by tarpon.. on Jul 20 at 8:57 AM

The Volt's gasoline capacity is being cut back

The Chevy Volt plug-in electric car from GM is one of the most desired new cars coming to the market.  Everyone is talking about the car's stylish design and relatively affordable price tag of around $40,000; not bad compared to past electric cars totaling over $100,000 like the Tesla Roadster.  With sales planned to commence in 2010 and with a production model possibly being unveiled later this year, the buzz surrounding the new vehicle is intense.

One fact many people didn't know is that while the Volt is an electric car, relying first on charge, it also sports hybrid capabilities.  It features a 12 gallon gas tank, which will only kick in after the lithium-ion battery charge is depleted.  This could take the car 600 miles, thanks to an impressive 50 MPG projected fuel economy.

However, recent reports have revealed that GM, in a surprising development, has decided to cut down the fuel tank for the Volt.  They won't say what the new capacity will be, with the source only saying, "We're working on that." 

The original goal for the Volt was to equip it to drive 40 miles on a charge, without using any gas.  This goal remains, and appears to be within GM's reach.  Additionally, since 40 miles isn't long enough for road trips or longer business travels, GM planned on adding the gas tank.  The gas does not power a traditional engine, but rather a generator, which provides enough charge to keep going, and actually performs more efficiently than most gas-engines.

GM has revised the target range to 360 miles, which would seem to indicate a fuel tank of 7.2 gallons.  The reasoning behind the cut is research that cars, on average, travel less than 40 miles a day.  While GM wants to provide a comfortable extension to this range, it decided that 600 miles was a bit excessive.  Many older sedans don't get much more than 300 miles on a 12 gallon tank, so the new range seems relatively reasonable.

Jim Hossack, vice president of AutoPacific, an automotive research and consulting firm states, "Most cars today have a range of more than 300 miles and less than 400 miles before refueling.  GM didn't need a longer range because most bladders can't go 600 miles.  By going with a smaller tank it means GM can take weight and price out and make Volt a little lighter and a little cheaper, and that's what you call making an improvement."

While GM's move should help it cut costs and cut down slightly on the weight of the vehicle, it may come as a disappointment for fans of ultra-long treks across the country.  Still, it is dubious that such minor gripes will be able to do anything to quell the PR frenzy surrounding the Volt.

At its price tag, even with possible subsidies, the Volt will likely fall into the luxury car class.  However, with its wild popularity and sleek looks, it seems likely to thrive in this class, or whatever class it may enter as prices drop.



Comments     Threshold


This article is over a month old, voting and posting comments is disabled

RE: Hybrid
By Jim28 on 7/10/2008 10:49:11 PM , Rating: 2
You don't know the math/mechanics of power transfer apparently.

Motor generater sets are above 90% efficient for power transfer and are widely used on ships for this reason and because they are damn near bulletproof.
And like the poster above said, the battery conversion factors are very high.

The difference that you can't see is that the gas engine is tuned and running in it's most efficient band, producing peak HP for a given fuel consumption. This gives you the ability to use a smaller engine with higher power output that can produce enough juice to power the car. It does not require three times the power, it requires at most 1.2 times the power for a good series hybrid design.
Also you don't need a tranny so that weight is saved and is more than enough to cover the generator weight.


RE: Hybrid
By William Gaatjes on 7/13/2008 8:29:33 AM , Rating: 2
I agree totally.

Using series hybrid has only advantages.

to some it up for Paul :

1. No heavy transmission, cuts weight and you can use this saved weight to put more batteries in the car.

No direct powercoupling/distribution stages to combine output power of ICE and electric.

2. i may be wrong but i am guessing that the electric motor is a 3 phase type and the electronics to switch these motors are highly efficiënt too. 3phase motors are widely used because of the high efficiëncy( if i am right > 90%) simple structure and high reliability/ endurance.
There is a big library of information for these electrical motors.

The generator is 3phase as well.

However you first have to normalize the output to the ICE to kw , this normalized output is input for the generator.
some loss for the generator , some loss for the electronics , some loss for the motor and some loss in bearings and so on. Yes nothing is 100% efficiënt.

VOLT :

you get ICE > generator > electronics > motor > drivetrain > wheels.

current cars :

ICE > transmission > drivetrain > wheels.

You would say that there are less conversion steps, but the efficiëncy is so much lower for the ICE that the volt still wins.

I am wondering why they didn't go for motor driven wheels.
You know, where the motor is build inside the wheel it self.
This would give 4 smaller motors and a easier way of getting energy back when braking. It would also save some drivetrain weight cause you don't need that anymore too.

3. As has been sad above the ICE runs constantly at 1 constant rpm value where the efficiëncy is at it's highest.
But there are more advantages. 1 constant rpm means you can
tune the engine also for vibrations, weight, maintenance, reliability/endurance and as mentioned output power.
I am sure there is some electronics after the generator that monitors the ICE to make sure that the load the generator exposes to the ICE does stay within an upper ans a lower limit. The key to make this all work is the electronics to adjust and control the ICE. And the car manufacturers have a lot of experience with that.



"If you mod me down, I will become more insightful than you can possibly imagine." -- Slashdot














botimage
Copyright 2014 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki