GM-VOLT : Chevy Volt Electric Car Site

In some recent posts, we were able to find out and discuss some important details about how the Volt’s li-ion battery pack is intended to function. One of the most critical facts we obtained from GM is that the 40 mile all-electric driving range will occur within 50% of the batteries maximum charge, or 8 kWh out of 16 kWh total. This translates to 200Wh/mile of energy consumption.

We also looked at the ability of the combustion engine (53 kW maximum) to keep the battery charged and how it might operate to do so. This generated some very intriguing discussion and further questions.

I went back to GM and had some discussion with other sources familiar with the Volt’s engineering, and have been able to elucidate the following more accurate facts:

As per Rob Peterson, GM spokesman, the battery will operate in the 50% “swing” zone, but actually, the batteries full point will be 80% (not 100%). So its charge state will actually vary between 30% SOC and 80% SOC. This translates to the following analysis of battery capacity:

In terms of the on-board generator, the peak power of 53 kW will rarely be used, only in extreme conditions. Peak efficiency will be at around 30 kW, which is what the car should require at 65 mph slightly uphill, although the actuals of mass and energy requirements are not final yet.

The engine’s job will be to maintain the battery at a SOC of 30%, and will do so by continuously matching the average power requirement of the car once it is turned on.  Those energy requirements will roughly be about 8 kWh in the city, and 25 kWh on the highway.

Another interesting note is about the time course of recharging the battery on the road. If one tried to recharge it by maxing engine output, the cells’ temperature would get too high, so the idea of rapidly “refilling” it on the fly and then cutting off the generator wont apply. Rather, it seems, the engine will continue to run, constantly matching the needs of the car to keep the battery at 30% until you stop driving.

Interestingly, the motor will likely be programmed to increase rpm when you step on the gas and quiet down when you stop to “simulate” the driving effect people are already used to. This will avoid the sudden unexpected ons and offs.

The graph above illustrated how the pack shall operate.

Tom Stephens, GM VP Global Powertrain

I had the opportunity to pose this question to Tom Stephens, who is General Motor’s Group Vice President of Global Powertrain and Global Quality.

Mr. Stephen’s is highly involved and interested in the development of HCCI, and the ideal person to tell us about it’s applicability to the Volt.

Here is the conversation:

GM-Volt: “Is this engine type (HCCI) being considered for the Chevy Volt?”

Mr: Stephens: “HCCI is a technology that is just emerging from the laboratory and won’t be ready for production when the Chevy Volt is introduced. However, when HCCI is ready for production, the Volt would be one of the many applications under consideration. ”

GM-Volt: “Are you aware of which engine that will make the first gen Volt, or is this still under discussion?”

Mr. Stephens: “The engine for the Chevy Volt is still under discussion.”

Overall, my feeling about this exchange was very positive. Coming from a man in his position, there was a very clear sense that the Volt is being produced, and the HCCI engine was even too new technology for it. Obviously, GM does not want to hold up the Volt’s production one iota.

Also it is clear that GM engineers still have more work to do in figuring out exactly what type and configuration of combustion engine will be best for this car. Bring on the mules.

Soon after the Chevy Volt concept was first announced, A123 Systems announced that they were acquiring a company called Hymotion.

We know that Hymotion specializes in building add-on plug-in lithium-ion battery packs that extend the electric range of existing parallel hybrids such as the Prius or Ford Escape hybrid (as well as invalidating their warranties)

Today a report out of Canada expands on some details of this company and the A123 relationship.

The company hopes to step in for owners when the existing NiMh battery packs begin to die, and hence the car is already past warranty.  The user could then substitute one of these packs and wind up with longer electric only driving.
So far the 8-person Canadian company has sold a meager 30 units, with 35 more on order. They hope to sell 2000 units in 2008.  A123 now owns them and will supply the batteries.
So could you get a Volt effect by buying an old Prius and retrofitting it?  If A123 gets chosen to makes the Volt’s battery packs will they be competing with themselves?
There are problems with this add-on approach.  For one, the electric motor isn’t meant for fast or powerful driving and may not handle it well.

What do you think? Is it a good idea?  Or should we wait for our Volts?

HCCI stands for Homogeneous Charge Compression Ignition, and is a new type of combustion engine paradigm. Traditional engines, with which we are all familiar, use spark ignition (SI). In that system, a spark plug fires and ignites the fuel in the combustion chamber forcing the piston to move. In HCCI engines, the fuel is compressed within the chamber and is able to ignite through compression at multiple ignition points (as opposed to the single one at the tip of the spark plug).

This is referred to as a lean combustion process, and occurs at a lower temperature. This leads to lower CO2 output and improved efficiency, allowing for a 15% increase in fuel efficiency. The process is said to nearly equal diesel engines in terms of fuel efficiency, but does not require the expensive processing needed to deal with noxious diesel emissions.

On August 24th, GM announced that two drivable cars using HCCI engines have been demonstrated, the first time that this type of engine has left the laboratory. The cars were a Saturn Aura and an Opel Vectra, both with a modified 2.2L Ecotec four-cylinder engine.

Apparently this particular type of engine is very good when confined to a single lower RPM. At high engine loads and fast speeds, these concepts have to be shifted to spark-ignition.

Based on these special properties, one might think that the HCCI engine represents the ideal agent to act as the Chevy Volt’s generator.

We think the initial Ecotec engine first announced with the concept could be out of the final plan, and ethanol remains in, but there does seem to be wrangling going on at GM to decide exactly what combustion engine the Volt will use. This may represent a logical choice. I am not aware, though, of HCCI being demonstrated with E85, although it is theoretically possible .

To learn more about this amazing new technology, read Sam Abuelsamid’s test drive experience here.

I am trying out a new feature here on GM-Volt.com. Just as the GM execs are meeting every two weeks to discuss progress on the Chevy Volt’s development, I thought it would be a good idea if I posted a video wrap-up of the past two weeks news, information, and events related to the Chevy Volt. Look for it every two weeks on Sundays. Feedback is welcome.

[flash http://www.youtube.com/watch?v=VCSygno1830 width=272 height=224 ]

Bloomberg.com has published a surprising interview with Bill Reinert, national manager for advanced vehicle technology at Toyota’s U.S. unit.  He is reported to express uncertainty at what the size of the plug-in hybrid market will actually be.

He goes on to note that there is indeed much enthusiasm about plug-in hybrids right now, but is suspicious as to whether people will adopt these vehicles at the end of the day.

This articles other interviewee is Scott Miller, chief executive officer of Synovate Motoresearch, a market research company .  He tells us the interesting fact that the awareness for the idea of plug-in hybrids is low.  A survey is mentioned in which only 10% of respondents said they would be willing to pay a substantial premium in order to get a car with this technology.

I think this report does raise some important issues.  Clearly, we here at GM-Volt.com are dedicated enthusiasts.  We also know that >474,000 people voted for GM to produce the Volt on their website.  Bot how can you determine exactly how many people are out there ready to buy a Volt?

To me, widespread acceptance of this car is a no-brainer, and in the future all cars will work with similar technology, and probably sans the generator, as batteries improve.  New technology always has a slow initial adoption curve, but it will happen.  GM is advertising the car very heavily, which is highly unusal for a car that doesnt exist yet!

It is also my hope that this site will serve to educate people about the car and let them know how great the concept is.  So if you haven’t already, spread the word about it to your friends, families, and colleagues!