DDB

Know what's funny about these models? IMO as much as you can create an environment that mimics wear and tear, you can't do a 10 year test without waiting 10 years. We aren't ever going to know for sure until the clock hits 2018. But by then we'll be in the 3rd, 4th, or even 5t generation won't we, so it's probably a moot point.

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Dave

'05 Passat powered by Biodiesel
'54 Corvette

TEG

Companies try all the time to get away with simulations and projections.

I recall once a major hard disk manufacturer put long ( > 5 years) MTBF ("Mean Time Between Failure") stats on their new drive based on the worst case expected lifespans of the individual components. The whole batch was made with the wrong lubricant in the motor bearings, and they had widespread failures within a year. That kind of stuff makes you suspect durability projections for new products.

We had a similar problem with bad capacitors (again a manufacturing goof with the wrong chemistry in the component) in a large number of desktop PC from a major manufacturer. Like clockwork they all started to fail within a short time. Looking inside, the capacitors were obviously "oozing goop" all over. We ask the manufacturer to replace the whole lot. They said "there weren't enough reported failures yet for a recall, so they would send a technician out to repair the faulty units". We tried to get them to swap motherboards on all systems at once but instead we had to go through a ritual of calling the repair depot back every few days as another system would go out.

Big jet planes used to need to log lots of test flight hours before they were certified for use, and rules for trans oceanic flight used to call for more than 2 engines. A recent model of popular jet was granted immediate exceptions to the usual rules based on computer projections. On its' maiden flight with company execs aboard the jet engines experienced a flame-out condition that wasn't predicted by the computer models.

Oops.

stopcrazypp

Well, as TEG mentioned, this is just the standard way of doing testing in most industry. The Volt really doesn't have 10 years to wait around if they want to release their car in 2011 or 2010. So budget and time constraints really cut into testing time and effectiveness, esp. for smaller companies. Which is why was so hard to make a mainstream car these days, there is so much testing. But I think we are glad that Tesla went through at least most of the tests, including the federal ones. In some of the smaller companies, like the ones who sell "quadricycles", there will probably be close to NO tests; saves them a lot of time and money.

Actually like malcolm mentioned, this exposure of testing is more like a PR blitz, designed to assure the public and media that the cars will do well. In the end, we may not get the full results (besides from pass/not pass) or most of the details of the testing. That's likely to stay internal, unless there is another PR round at the release of the car (since GM obviously wants this to be a crown of technical achievement for them and it's also one of their responses to the Prius and criticism of the killing of the EV1).

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Because there are tons of crazy people in this world...

malcolm

Ooops!

I got the right answer, but used the wrong numbers.

The Roadster gets 220 miles on the EPA Highway (combined cycle) not 245. However, not all of the Roadster's 53kWh is available to the motor. 10/11th of the ESS energy can go to the motor and 1/11th powers the car's computer systems etc.

Which gives 220/48.2 = 4.6 miles/kWh.

Anyway, the heavier Volt will still need 5 miles/kWh to get 40 miles from only 8kWh. GM are going to have to increase the depth of discharge - maybe as much as 90% to 20% instead of 80 to 30.

Or drop the commitment to the 40 miles battery-only range.

Or use a gentler driving test cycle than the EPA Highway.

On a completely different line of thought, what would happen if the ESS could change the "sheet" of batteries used to power the car's electronics systems? Every few hundred miles (or every 5th recharge - whatever) the system switches over and a different sheet gets a rest from powering the motor and is required to take its turn powering the other subsystems.

Or perhaps the changeover rate should be controlled by average pack temperature - in hotter seasons this sheet-cycling behaviour is faster than in winter.

malcolm

The Volt's crash diet has started:-

GM-VOLT : Chevy Volt Concept Site » Blog Archive » Volt Gas Tank Shrunk - Maximum Range Reduced

Hope they can bring the weight down.

Albern

An interesting post on the Volt website - from 2 12 gallons tanks to a single tank with a yet to be determined volume. What really caught my attention was the 50 MPG fuel rating in range extended mode. Can ICEs be that "efficient" when generating electricity for a vehicular application?

malcolm

Absolutely. The big advantage is that the ICE gets to run at optimum revs the whole time. Bit noisy in quiet traffic of course.

SByer

Heck yeah. So, assume that a company the size of GM can get close, if not match, the efficiency of the Roadster drive train, say, at 90%. Now, take your ICE, size it perfectly for the matched generator, and run the pair at the optimal efficiency RPM point, tuning the generator for the ICE, not the other way around.

From another view, take an ICE torque curve. Flatness comes from oversizing the ICE. Right size the ICE to provide a good torque peak - probably in the 3-4k rage - tune the matched generator to that. Much smaller engine than you are used to.

Overall, you're taking an engine that has pretty narrow efficiency bands, running it in that band, and driving a system that has a very wide efficiency band that's also quite high. Average goes up as long as the transfer of power isn't too inefficient.

mt2

And add to the equation that all energy being created by the ICE is being stored (within the efficiency limits of the generator and battery). No wasted energy by sitting idle at red lights or in grid locked traffic.

__________________
Mark Tomlinson
"I am not a trouble maker; I'm a catalyst for change."

malcolm

Positive noises continue:

GM-VOLT : Chevy Volt Concept Site » Blog Archive » Even Chevy Volt Battery Suppliers Surprised at GM’s Volt Aggressiveness

Love the quote from Ric Fulop,"Somebody lit a fire under [GM’s] butt in 2006........I’ve never seen a large company move so fast and put so many resources behind something."

Bob Lutz is on record citing Tesla as the Firestarter:

Q&A: GM's Bob Lutz on the Volt and More - US News and World Report

When Tesla announced they were building a car, that kind of tore it for me. I thought, "If some little West Coast outfit can do this, we can no longer stand by."