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Discussion Starter · #1 ·
CAUTION: This is a long winded post.

After the attending the VoltNation meeting in NYC, I have been trying to piece together some of the information that I have gathered from the GM engineers and from other comments by members here on the website. I don't profess to have any answers, but just some information that may be of interest.

After reflecting on the meeting and all the things that we learned on March 19th, I started to think that GM, as a result of doing the EV-1, was not going into this project with no knowledge of electric vehicles. In fact, why wouldn't they start with the EV-1, and basically modify/improve/update what they already have? Based on that premise, I looked into the EV-1.

From one of the DOE websites, I found a great deal of information on the 1999 EV-1 that included NiMH batteries. The link is:

Note here that the EV-1 included electro-hydraulic brakes (also in the specs for the Volt). See Volt specs at:

This car also had a heat pump climate control system w/Pre-Conditioning Feature. This means to me a combined AC/heat pump heater, with the ability to warm or cool the car prior to driving the vehicle. Therefore, this system has already been designed by GM in the past.

The NiMH battery pack weighed 481 kg, or 1060 lbs. The car's total weight was 2848 lbs. I have read that the curb weight of the Volt should be around 3200 lbs.

The performance numbers are also interesting. The Volt is designed to go 40 miles on 8 kWh, or 200 Wh/mile. At 45 mph, the EV-1 required 127 Wh/mile. At 60 mph, the energy consumption increased to 168 Wh/mile. The one statistic that seems disappointing is the charging efficiency. The specs indicate 373 Wh/mile, which is more than twice the 179 Wh/mile needed for the "Driving Cycle". It will be interesting to see this statistic for the Volt.

Another interesting site provides a cutaway view of the EV-1 with some of the construction details. This link follows:

Note in the chassis drawing that the drive system uses a motor, a gearbox, and a differential. For the Volt, this drive system is shown as direct drive. I believe this is shown in the attached drawing.

The drive motor is located between the frame, in line with the two front wheel hubs. I estimate the diameter of the tires to be 29.5 inches, so at 120 mph, the rotational speed of the tires/motor would be a nominal 1400 rpm. Therefore, the drive motor would be controlled such that it operated 0 - 1400 rpm, with the best efficiency desired in the 300 - 800 rpm range.

Eliminating the gearbox and differential from the drive system for the Volt also leaves more room in the front for the ICE.

Note that the EV-1 had its batteries in a "T" configuration, similar to that proposed for the Volt. The EV-1, however, needed 1060 lbs of batteries, while the Volt will have a 400 lb battery pack. Again compare the Volt chassis to the EV-1 chassis.

It also appears that the suspensions for the two cars will be similar, and both use low rolling-resistance tires.

Next I want to examine the overall exterior design. The EV-1 had an aerodynamic drag (Cd) of 0.19. GM has stated that this parameter is of the utmost importance in achieving good electrical range. The Toymota Prissy has a Cd of 0.26, so I believe GM will try to best this number.

To get to 0.19 Cd, GM used a teardrop shape for the EV-1. In fact, the front track width is 57.9 inches, but the rear track width is only 49.0 inches. This trait may find its way into the Volt as well. Note that the front of the EV-1 is very smooth, with essentially no grill. A frontal view can be seen at this link.

Now look at the teaser picture of the Volt.

See any similarities? Although the headlamp placement, spoiler, and psuedo grill are different, the basic shape seems similar to the EV-1.

Next, it appears that GM looked at a 4-person EV-1. See the attached link:

Note here the basic shape is retained, with a longer cabin. This provides some other speculation as to the Volt's basic appearance.

Now that we've examined the EV-1, let's look at the Volt concept. I like to start by looking at the side view.

Note that the specifications indicate the overall length for the concept vehicle is 170 inches. With 21" wheels, I have scaled this picture ( I have a higher resolution picture) and estimate that the wheel base for the concept is about 125"! (If anyone has other information, it would be helpful). Note that the Cobalt's wheelbase is 103.5" and the new Malibu's is only 112.3". At the VoltNation meeting, it was revealed that the Volt would be built on the new Delta II platform, and its wheelbase is supposedly somewhere between the existing Cobalt and the Malibu. Therefore, there will be significant changes in the Volt compared to the concept vehicle.

For discusssion on some of these changes, I would refer you to this site:

Here the author talks about the top view of the vehicle and the sides being "flat" and the need for a "parabolic" shape of the car. He also mentions the increased front overhang (hints at lower wheelbase). The grill is blocked off (no air flow through the grill).

Therefore, for the general design of the Volt, I am speculating that it will have a shape that is similar to the EV-1. The EV-1 had a wheelbase of only 98.9", and the Volt will likely be ~ 108". This will allow room for the added cabin space, as the EV-1 was a 2 seat vehicle.

I expect the front of the car to be similar to the EV-1 in shape, with a wider track in the front, and smaller track in the rear. For aerodynamics, the wheel rims may be solid (like bicycle wheels during the Tour de France time trials). Although the front of the car will be different, the cabin shape and rear may be very similar to the concept vehicle, with the exception that the sides will have the more "parabolic" shape.

I anticipate a sunroof option, and the use of high technology solar glass, similar to that used in the EV-1.

Although it has only been less than 10 years since the NiMH EV-1 was introduced, there are a number of improvements that I see to the Volt (excluding the Li-Ion batteries).

1) The use of low wattage LED lighting
2) Next generation low rolling-resistance tires
3) Direct drive motor with no gearbox
4) Integrated ICE and battery coolant systems
5) Global design
6) Four passenger capability
7) Home charging - no special external charger required
8) More powerful electric motor
9) Five door/hatchback design

I'm sure there are others that I missed.

So there's my conjecture as to what the Volt may be and how it may look. After reviewing the EV-1, I realize that the Volt is, as far as I am concerned, just the next logical extension of that vehicle.

1,797 Posts
After reviewing the EV-1, I realize that the Volt is, as far as I am concerned, just the next logical extension of that vehicle.
Well, I think at the time the EV-1 was being planned and built, it was pretty mich intended as a niche vehicle, similar to the Honda Insight a few years later. After all, a 2-seater is going to have a very limited market.

I'm sure they thought at the time that if the technology took off, they'd come out with 4-seater versions, and many of the other things. (there was even a prototype with a range extender)

218 Posts
Note in the chassis drawing that the drive system uses a motor, a gearbox, and a differential. For the Volt, this drive system is shown as direct drive. I believe this is shown in the attached drawing.
You're right: now that I look at the picture, I see the half-shafts go right into the electric motor, one on each side. Does this mean that there are two separate rotors?

Senior Member
3,689 Posts
BillR, Are you a forensic scientist? Nice analysis (accept for the cheap shot) ;) Do you have any more information about the charging efficiency. What it included (plug-to-wheel)? I would expect it to be better for the advanced lithium-ion batteries but this specifications is very important for comparing to other technologies.

240 Posts

Good point! Here are a few others that are intriguing also:

20070273223 Repositioning of power capacitors on electric motors.
20070295544 Regenerative braking "halo display". Sounds cool.
20080034767 Efficient and safe AC operation by fluid temp monitoring.
20080046151 Some type of sun position indicator for auto components. Not quite sure whats going on in this one.

All of these seem focused on the Volt, IMO.

There is also a whole set of patent apps 20070285059, 60, 61, 63, 97 . These all apply to monitoring the performance or EOL condition of the battery pack. Cant tell if its for in the car or the lab.

Wish I had more time to check all this stuff out.

35 Posts
They should use sony's new oled screen for display and entertainment puposes

heres a link if you dont know what that is
They are trying to keep the price down, using a $2,500 screen is not the way to do that.
Also, while that screen would be freakin sweet in your house, it doesn't matter that it's only 3mm thick when it is in the dashboard, it could be a foot thick and we'd never know because we only see the front of it.
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