backtop


Print 76 comment(s) - last by XtremeM3.. on Oct 20 at 3:04 AM


Eight 2011 Chevy Volts took the 1200-mile roadtrip.  (Source: Jeffrey Sauger for General Motors)
The Volt is withstanding the rigors of road testing admirably

The first preproduction models of the 2011 Chevy Volt hybrid electric plug-in vehicle were built earlier this year.  Since then, the vehicle has been put through a number of rigorous tests.  Starting yesterday, a fleet of eight Volts launched on the most ambitious test of the vehicle to date: a 1,200 mile road trip.

Chevrolet Volt chief engineer Andrew Farah is among those making the round trip from the Milford Proving Ground through Ohio, Pennsylvania, Maryland, West Virginia, before returning home.  The drive will take a few days and will require approximately 4 tanks of gas.

The drive is dubbed the "65-Percent Drive" according to Autoblog, which in GM-speak means the test drive made when 65 percent of the vehicle's hardware and software is done.  Reportedly, GM is actually about 90 percent done, but is just sticking to its traditional naming.  GM will complete 70, 80, 90 and 100 percent drives in coming months.

One thing GM is still tweaking is how much power from the gas-engine generator to put directly to the electric drive motor, versus using the generator power to charge the batteries.  GM is finding that frequently putting the power directly to the motor improves performance.  However, the generator will still charge the batteries in some cases, as well.

The engine will be run between 1,200 and 4,000 rpm, using factors like speed and power load requirements to decide on the necessary speed.  GM wants to keep the engine between 30 to 100 percent load, as higher loads reduce pumping losses.  GM was tight lipped about fuel economy under the old method (sustained charge) or the new method (variable speed, some power going directly to the electric motor). 

The company did say that the prototypes are getting good mileage -- over 300 miles on a tank of gas -- when operating in generator mode.  This is in addition to the vehicle's 40 mile all-electric range.  Another interesting test will be when GM runs the car's gas engine on E85 ethanol fuel.  The vehicles are FlexFuel designs, so they can enjoy both gas and ethanol.

As to the battery mode, the batteries are performing well and aren't getting too cold or too hot, both conditions which can degrade performance.  The cars aren't yet reaching the 40 mile target on a charge, but GM expects to pass that milestone on the next test, with tweaking.  On the trip, GM is testing vehicles both running on a depleted battery charge, and a full charge.

GM is also looking to fine tune and minimize noise, vibration, and harshness (NVH).  Currently, the gas engine typically won't turn on until the car is moving, at which point the noise will be drowned out by the wind and road noises.  GM, nonetheless, is pleased with the performance, and plans to further reduce NVH by tweaking vehicle parameters that effect the road and wind noise.

Other GM engineers were off testing Volts at Pikes Peak in Colorado.  One key concern is whether the Volt will reach a "tipping point", where the gas engine can't sustain battery charging, and the battery becomes depleted below the typical minimum of 30 percent charge.  Even a strenuous 14-mile trip to the 14,000-foot summit was unable to overwhelm the 100 hp generator, though, so it appears that the "tipping point" will never be reached in real world situations  -- if GM's claims hold true.

A critical test to come will be how the vehicle performs in cold weather.  In cold weather, the Volt starts with the generator running, to help heat up vehicle and jump-start performance.  Battery performance typically suffers incrementally worse degradation, the colder it gets (this is a major argument for ultracapacitors which perform favorably, but are more expensive).



Comments     Threshold


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

*sigh*....not yet?
By Souka on 10/16/2009 12:10:13 PM , Rating: -1
Ok, I'll start by saying I"m not a fan of US cars, but I did own/drive a Ford Exploder for 5 years...I liked it, great family car, but thing was constantly needing repairs.

Anyhow, back to why I'm typing this.. what gives on the battery range?
"This is in addition to the vehicle's 40 mile all-electric range." Ok... so again the 40 mile range on battery is stated as it is in most news articles or press releases.

But... this statement, which is a statement from GM itself, not an advertisement, really bugs me.
"The cars aren't yet reaching the 40 mile target on a charge, ..."

Not at 40miles yet? And that's with their trained drivers doing their best? Come on!

This is sounding like laptop battery life... "10hr battery life" but in reality it's more like 5hrs.

So GM will say "40 mile range" but in reality when "Joe Plumber" drives it'll be more like 20 miles.

And much has GM spent on this? How much has they government GIVEN GM? Correction, how much money has the american tax payers given to GM?

I'm not "mad" at GM or the Gov. But feel a bit sadden at the situation...that's all.

My $.02 of rant/sadness.




RE: *sigh*....not yet?
By kaoken on 10/16/2009 12:42:16 PM , Rating: 2
Well that's what they are working on : )


RE: *sigh*....not yet?
By Spuke on 10/16/2009 1:43:20 PM , Rating: 2
quote:
I'm not "mad" at GM or the Gov. But feel a bit sadden at the situation...that's all.
Now I understand why corporations are reluctant to discuss products that have not been introduced. The ignorant masses always seem to know better than the experts designing and building the products.


RE: *sigh*....not yet?
By Keeir on 10/16/2009 2:31:03 PM , Rating: 3
quote:
Not at 40miles yet? And that's with their trained drivers doing their best? Come on!


Errr... are you blind? Notice that there are missing headlights? Bumbers and stuff that don't quite align.

I also image the software is very rough at this stage (more than 1 year to showtime). Pretty much, I think getting within 5% of the goal of 40 would be typical at this stage of development.

quote:
So GM will say "40 mile range" but in reality when "Joe Plumber" drives it'll be more like 20 miles.


GM has stated that the Goal is to achieve 40+ miles on the EPA City Driving Cycle. Computer modeling is given them well past 40 miles AER on the EPA city. Real-world does not yet match the modeling, but thats scarely a surprize.


"Young lady, in this house we obey the laws of thermodynamics!" -- Homer Simpson














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