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Joseph Simpson

Author's follow up note:

Since I wrote the pieces on the Volt, numerous comments and other pieces of analysis have appeared. Of particular note was this report on the bbc news site:


It suggests that the timescale to building this kind of car is in fact two to three years, which I'm quite surprised about. Obviously new technology needs thorough testing by a big auto maker, but everything I read, everyone I speak to who is knowledgable about the subject of battery technology and drive systems, suggest it can be done today.

So I'm even more suprised to find established auto analysts questioning the viability of the technology:

"Walter McManus, director of automotive analysis at the University of Michigan, said at this stage it was tantamount to a "magic" car: "They didn't tell you when this E-Flex was going to be ready. The battery technology they're dependent on is not ready yet. It's a physics issue and just pouring money into it isn't going to solve it.""

As I understand it, the Volt will use very similar batteries to those being employed in the Tesla roadster. So I don't see how this battery technology is "not ready yet". The cost is a problem, I admit - although with a big company like GM on board this will improve, but the technology exists now, and is improving by the day.

I'd love to know your thoughts on the matter, or any insight you have on battery technology and electric drive.

Thomas Bjelkeman-Pettersson

This type of hybrid powertrain has in fact been in use in Stockholm city busses for a number of years already. These busses run on E85 and have a small car engine (2.3 litre SAAB engine) powering the buss. Details about the design can be seen in this following PDF document p.17 (unfortunately only in Swedish, the Swedes are not got at this PR thing).

Joseph Simpson

Further comment and analysis was made on NPR's science programme last week. There's a 17 minutes audio discussion here:

The comments suggest that the timescale for the Volt really is going to be more like 3 to 5 years, rather than 1 or 2.

Interestingly, the show host asks some of the guests whether the europeans are closer to launching this technology than the Americans, to which he gets the reply that the American's are ahead.

I think the general perception is that this is true, but I'm not so sure of the reality. The European auto industry has generally hung its hat on the hydrogen fuel cell as being the answer, but in fact, if it does take GM 5 years to get the Volt to market, then there's a probability that the Renault-Nissan alliance will beat them to an electric car launch:
http://www.forbes.com/business/feeds/afx/2006/12/11/afx3243786.html (skip past the intro page).

Daniel Sjöholm

Now check my website as well. www.formadera.com
not much on there for now but hopefully will change in the future.
See you around, man!
Keep up...all that writing!!

Anatole Maher

These are details culled from reading several articles on the Chevy Volt
1) A 400 Lb Lithium ion battery, with 16 kwH capacity supplies the (electrical) energy for the first 40 miles. This is supplied to a (nominal) 150 hp(?) DC(?) electric motor, 273 lb-ft torque, which is the only mechanical driver for the car
2) Roughly that would correspond to 2 hours' driving of approx 20 miles distance each hour.
16kwH/2 = 8kwH per hour energy usage 8 kw average power output for one hour
It requires 8 hours to recharge the battery from a 120V household outlet. 16kwH/8 hours = 2 kw = 2000 watts
2000watts/115 V =17 amp average charge rate ...the rate would vary depending on the charge in the battery
3) A 1.4 litre gasoline(any IC) engine powers a 53 kw generator, which then EITHER supplies current to the driving motor OR to recharge the battery
4) Using the figures provided, 150 (peak?) hp motor and 273 lb-ft torque, this would correspond to a motor speed of 2885 rpm
Assuming 22 inch tyres (which I have on my Honda Civic, the wheels would rotate 153 rpm for each 10 mph, 1530 rpm at 100 mph
!00 mph is given as the top speed, presumably when the motor delivers its peak 150 hp, so a speed reduction of 1.88 is included somewhere in the drive train
After considerable search, was unable to find any diagram of the drive train, the torque-hp-rpm characteristic of the drive motor, nor how the motor speed is controlled
I would really like to see these details. Thank you
5) Lastly, the claim made by the GMCEO Fritz Henderson that the daily cost for charging the battery is 40 cents based on 5 cents/kwH is total hogwash. I pay 12.83 cents per kwH where I reside. He must have solar power or GM pays his electric bill

Anatole Maher

On reviewing my post I note a question in both my data and your item 4
According to what I've read the (small)gasoline engine is 1.4 litre displacement, powering a 53 kw generator which, somehow, while driving kick in to furnish electrical energy (current) to
EITHER the driving motor nominal (peak)150 hp. 112 kw
OR to recharge the battery
This implies that the total power demand under driving conditions (incline, road and wind resistance, acceleration) is less than 53 kw
What is the efficiency of the combined drive motor and drive train?
Also, referring to the 40 miles of city driving, here in Florida where the temperatures have exceeded 90 F ,I have the AC on continuously, how much power does that draw?

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