It still doesn't explain their claims of the lack of battery technology for it given that NiMH can do the job just fine in regard to performance and range(and is over 10 years old), nevermind AltairNano technologies batteries or those from A123 and both their cycle life claims(Altair's 10,000 cycles was even confirmed by Aerovironment). Cost could be an issue with those mentioned Li Ions, but repeated studies have confirmed < $300/kWh for NiMH. UC Davis' Futuretruck reports have sometimes used $225/kWh for volume production of NiMH based on these studies and from interviews with those knowledgable of it. The Ovonics last 1,200 cycles to 80% discharge according to Cobasys. This is bordering on 'good enough' for the Volt, even if you might need to replace the pack every 40,000 miles or so due to deep discharging. The cost would be about at parity with or slightly less than using gasoline in volume production compared to a typical gas car.

I hope GM delivers on their promise this time; the technology can do the job. What they did with the EV1s in spite of working technology, willing buyers, marketable range, sufficient battery life, and a not too unreasonable mass production cost was inexcusable.

In the future, perhaps they might consider a pure EV Volt? If the drag coefficient is cut down that low, a 4,000 lbs car with 0.21 Cd, 2.14 square meter frontal area, Crr of 0.010 tires, 30N sliding friction, 90% combined motor/controller efficiency, and 20% stray/driveline/accessory losses would need about 21 kW from the battery pack to maintain 70 mph(31.2 m/s).

A 16 kWh pack would thus give it 0.762 hours of run time, or a 53 mile range at that speed to full discharge.

I'm reasonably certain that GM knows what they are doing and wouldn't allow the pack to become that discharged, so giving a 75% or 80% discharge limitation for whatever li ion pack is in this thing would give about the required 40 miles plug in range.

If GM delivers, we have a car that no one will be able to keep on the lot. If GM is doing smoke and mirrors, I hope they die as a company so we can move onto better things. Which will happen I can't say.
Posted by: John Westlund

John Westlund: Would you really buy a car that needs a battery replacement at 40,000 miles? I doubt it. We put almost 20,000 mi per year on our Prius and even replacing that battery pack after 2 years would be prohibitive. For a plug in it would be a huge expense. I read comments like the above all the time from other EV nuts who are just completely unrealistic about battery technology.

Of course, it's true you could make a Volt right now with off the shelf NiMH batteries. The big problem is to make it a good marketable car. It will weigh too much, the batteries will wear out quickly, it would cost about $10,000 too much for the market, and it would be a dismal failure. Hundreds or even thousands of EV nuts would buy them and overlook these huge drawbacks, and villify GM for pulling the plug on it when it fails in the marketplace.

Realize that a Prius is engineered to NEVER EVER let the batteries fall below 50% charge. This is the only way to get them to last 10 years. For the much larger battery pack a plug-in needs, it's simply not going to be acceptable to lug around a large expensive battery that you can only use half of.

Battery technology is truly a huge problem, and GM has their work cut out for them. Let's hope they succeed.

Posted by: Art Invent

The battery problem is something I agree with for the PHEV application within limits, which is why I think a PHEV is overall a bad idea! Why? The battery cycling requirements are more demanding for a PHEV than long range a pure BEV. Wheras the PHEV is likely to be cycled deep routinely, the BEV is seldom going to be cycled deep in comparison due to its increased range per charge. A PHEV with a 16 kWh NiMH pack and say, 1,200 cycles to 80% DoD and 40 miles range to 80% DoD will last 48,000 miles not factoring in shelf life and other variables. A BEV with a 40 kWh pack and 150 miles range to 100% DoD with a pack that lasts, say, only 1,000 cycles to 100% DoD, will have a 150,000 mile pack life if routinely deep discharged, not factoring in shelf life and other issues.

And by the time the pack is considered 'spent', it is delivering 80% of its nominal cruising range. It's still technically usable, just not performing as well as it did new!

The reality? Some RAV4 EVs have passed the 150,000 mile mark and their first packs are still delivering about the same range and performance they had when they were new! There is suspicion in the EV community that they could last well over 200,000. These are only 26 kWh packs in unaerodynamic/heavy vehicles with 80-100 miles highway range. Southern California Edison has repeatedly evaluated these batteries as well and has found them acceptable.

Shelf life? The RAV4 EVs are proving that the shelf life of the Panasonic EV-95 NiMH modules is acceptable, and so far at minimum 10 years. Nickel based chemistries usually last far longer than PbA, Li Ion, NaS, NaNiCl, ect. Thomas Edison's NiFe batteries from the early 1900s will still deliver near nameplate specs even today after repairs, and there's many hobbyists with military surplus NiCds that have lasted decades. There is reason to believe that large format NiMH will have a shelf life that well exceeds the requirements for a consumer. I don't think today's off the shelf Li Ion comes close; Tesla has a reason they warantee their pack for 5 years, although I personally suspect it could last 10 if the charging algorithm and management/cooling system is as good as they say it is.

The cost of the batteries is due to many factors, the most significant ones for NiMH being materials costs and production volume, IIRC. The materials cost for NiMH can't be adressed much, but the costs with production volume of large format modules can; UC Davis quotes $225/kWh(I think this was in 2004) in volume for mass produced EVs. In the 1990s, Robert Stemple quoted $150/kWh in volume for 20,000 EVs a year, but this was before the cost of nickel shot up.

If you think large format NiMH would cost too much for the market, Li Ion from companies like A123 costs much, much more. Volume is key to getting price down. In low volume production from Toyota, the RAV4 EVs cost about $15,000 too much for the market in the 1990s. Mass production could have potentially gotten them down to parity. The market today is different; people pay $60,000 for these things on Ebay, used.

IMO, and the opinion of those who I've spoken with who are far more well acquainted with EVs than I am, a PHEV would be a lot harder to meet consumer requirements than a pure BEV. The BEV only has cost, economies of scale, and rapid charging infrastructure going against it(the first would be addressed naturally following the second). Range isn't a market issue if it is enough to meet a significant portion of the market(a few hundred thousand buyers nationwide each year). The PHEV has cost, economies of scale, limited deep discharge cycle life of its pack, and the fact that it will weigh even more than a BEV(due to all the required ICE related components) going against it too.

GM could really get the car to market if they gutted the hybrid powertrain from the Volt, and decided to mass produce it as a pure EV with say, 150 miles range and NiMH batteries. The GM EV1 did just that; without hardly any advertising, the demand was surprisingly large for a two-seater with minimum amenities and practiciality; the waiting lists went ignored and thousands of potential lesees were screened out for not meeting GMs strict criteria. A study titled 'The Current and Future Market for Electric Vehicles' found the market in California alone for a BEV with highway capability, able to seat a family, and 80 miles range was at least 150,000 cars per year. NiMH can do 150 miles range with ease using a 30 kWh pack in an aerodynamic midsize car(Solectria Force did 200 miles range using 30 kWh NiMH, IIRC, Toyota RAV4 80-100 miles range using a 26 kWh pack of NiMH), and up to 350 miles range in an ultralight(see Solectria Sunrise, 30 kWh pack).

Using the Volt's chassis and say, a 120 kW electric drive system and 40 kWh NiMH pack, the car could achieve the about the same cost as GMs proposed Volt PHEV would(if not less since you won't need ICE parts), deliver 0-60 mph in 8 seconds, weigh the same or less as the proposed PHEV, top 120 mph, seat 4 adults, do at least 150 miles range at 70 mph highway speeds, and have a battery pack that would itself last at least as long as a gasoline car would. Unlike the gasoline car, it would be a simple matter of replacing the pack when it degraded, and not the entire car.

Is there a mass market for that? I'd say yes. There's evidence to support the case of a significantly ignored market for long range EVs. Mitsubishi sees the obvious today, and Nissan is joining in. It wouldn't be a car for everybody or have the same broad market appeal as a PHEV, but it certainly would simplify a lot of things and make it easier to bring to market sooner!

The market would even expand with fast charge infrastructure. Aerovirnment in the 1990s could fast charge Ovonic NiMH packs from 0-80% in under 30 minutes. That's bordering on 'acceptable' for long distance travel if the infrastructure is set up. Altair Nano's batteries can charge in 10 minutes from 0-100%, even better(cost may be the issue with those. Don't know).
Posted by: John Westlund

There are drivers still on the road with Rav4-EV's that were spared the crushers with 70,000+ miles on them, and still getting roughly the same range 5+ years later.

Southern California Edison's torture testing concluded the Rav4-EV batteries had a life of 150,000 miles. Click here for the report
Posted by: Jeff M