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I remember hearing the 50 mpg figure being thrown around in regards to the range extender but I think it was supposed to be a 1.0L engine then. Has GM given any new numbers?
 

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Well it looks like if google is to believed it'll put out 66kW of power. Fuel consumption in the Opel seems to be around 40mpg.
 

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I hope GM eventually gives us a much smaller ICE option for those of us who don't care if we have to limp around after the electricity is gone. I can get my jollies in full electric, thank you very much. If I have been bad then I can limp around at 50 + mpg. The ICE will be lighter and so will the gas tank and the gas in that tank as will the cooling system, The coolant in the radiator, the oil in the engine pan, etc. down and down we go.
 

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Discussion Starter #5
So if the ICE outputs 66 kW, and we assume the generator eats 6 kW, that leaves 60 kW power for the electric motor. That's a bit more than the 53 kW we have heard before. Or will the generator eat more? And does that mean the ICE is only on part of the time at highway speeds, which would increase the effective ICE mpg rating.

So hypothetically if the ICE nominal rating is 45 mpg but it is only on 90% of the time, then the effective mpg rating would be 50 mpg. Is there enough info on this engine and on the Volt to get real numbers on that?
 

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I don't think that's how it works

The ICE only kicks on after the batteries depleted to 30%. If you drive less than 40 miles it should never kick on. I don't know how they're going to run the ICE after that point yet, but I've read that it will have 3 charging points depending on the load. Say it runs at the lowest rpm/highest efficiency point when the load is low. then kicks the generator up a notch to the 2nd rpm point when the load is moderate and the 3rd least efficient point when full power is needed. It seems silly to me to stop the genset once the battery is depleted and simply let it run at it's most efficient setting until the car is turned off, more power is needed, or the battery is recharged; because there is capacity to store any extra energy in the battery and that would reduce the wear and tear on all the mechanical parts.

This is mostly speculation on my part. Except for when the genset will start operating, but in my mind that seems like it would be the most efficient use of a series hybrid. It would make it very efficient and keep wear and tear on the mechanical parts at a minimum.
 

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According to this chart on the front page, the ICE will be starting and stopping to meet the demand, keeping the batteries just above the magic 30% figure

 

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huh

just kind of surprised they would cycle the engine like that. I figured they'd at least let it get up to about 50% before flipping it off. I wonder if they do it like that too extend the life of the battery.
 

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just kind of surprised they would cycle the engine like that. I figured they'd at least let it get up to about 50% before flipping it off. I wonder if they do it like that too extend the life of the battery.


Don't worry, this standard "house furnace" mode is only one of many possible modes. The software guys (and gals) will have to play with the mules for quite some time to come up with different modes of operation that fit under different conditions. For example:

1) Long highway drives - would want a more constant ICE running mode.

2) Extreme driving mode - Hot driving followed by breathers.

3) Limp home mode - Almost home and want the minimum charge when I get in the garage.

4) Quiet mode - no ICE operation desired.

5) Custom selection - driver would like to select a different mode.


Thus, you can see there there's a lot more going on than at first glance. As I like to say, if GM doesn’t provide it... The hackers will!
 

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I'm certain GM is doing everything it can to make this car acceptable to the general public on the first go-around. I have more hope in that than I do them engineering some modern marvel and screwing it up on a gamble the first time - so the engine thing don't bother me too much. I think if they can get it "right', then we'll see GM dial changes in at all the right areas.
 

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Discussion Starter #11
I'm not sure I would want any different modes for the ICE. I would prefer for it to stay in the high efficiency groove, and just turn off when it is finished recharging to the high water mark. I thought they are now improving mpg in regular cars by turning the ICE off even when you stop for traffic lights, so stopping and restarting the ICE should not be a big deal.

The only mode thing would be if the ICE is charging and notices the battery charge is still going down. I thought GM said that that should never happen, so I can not imagine them making a mode for it, but if I happen to be towing a trailer, I would probably like the ICE to kick up to a higher speed (assuming the generator can take it).
 

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just kind of surprised they would cycle the engine like that. I figured they'd at least let it get up to about 50% before flipping it off. I wonder if they do it like that too extend the life of the battery.
My understanding is that the gen set is never going to get the battery up to 50%. It's purpose isn't to charge the battery up to full but rather just to take over for the battery once it gets down to 30% or so. This should maintain the battery at about 30 something percent until you get a chance to plug it in again.

I am assuming that regen braking will continue to charge that battery though, so every time you step on the brake or go down a hill the battery does get charged back up. I wonder at what point of charge from regen charging the ICE will turn back off again?
 

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With VVT and what is essentially an infinitely-variable electric transmission, the 1.4 L engine/generator combination can efficiently "de-tune" itself to have optimal specific fuel/HP ratios and match virtually any load the software tells it to. Besides, standard hybrid technology has already found that engine cycling can be done smoothly and efficiently.

I suspect GM's modeling and testing is showing that because of charge/discharge efficiency losses, it is far more fuel-efficient to only run the ICE hard enough to feed power to the motor and wait for plug-in time to re-charge the batteries back up to capacity.

Living in an area that will demand both long-distance flat highway driving and extended high-speed mountain climbing, I personally really appreciate their plan to provide adequate ICE power to ascend the grades with more power than a '62 VW. I'm sure Bob Lutz's worst nightmare would be to see a Youtube video of his dream car crawling up a grade at 40 MPH with Yugos flying past it. Talk about a market-killer.
 

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Actually my first thought was that they were gong to use the same engine as the Chevy Cruze (except withoutht the turbo). Not that I'm complaining.
 

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From Wired:

That's all well and good from an engineering and accounting perspective, but is a 1.4-liter engine big enough? Absolutely, Nitz says. The engine will produce about 50 kW (roughly 67 horsepower), half as much as the electric drivetrain. That's more than enough to charge the battery while providing enough juice to keep the electric motor turning, Nitz says.

"Zero to 60, passing maneuvers, you'll be fine," he says. "The ability to actually use more than about 50 kW doesn't exist very frequently."

http://blog.wired.com/cars/2008/07/general-motors.html
 

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"The ability to actually use more than about 50 kW doesn't exist very frequently." – Larry Nitz, GM

GM’s smallest car, Aveo has a 1600cc ICE rated at 103HP (77kW) and weighs about 2500Lbs, much lighter than the Volt. If everybody is happy with Volt’s passing speed going uphill with depleted battery pack, then automakers should be selling more cars with sub-100HP ICE. Immediately we can reduce foreign oil import substantially. We do not have to wait for the Volt and other EVs and hybrids to reduce emissions and oil consumption.
 

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"The ability to actually use more than about 50 kW doesn't exist very frequently." – Larry Nitz, GM

GM’s smallest car, Aveo has a 1600cc ICE rated at 103HP (77kW) and weighs about 2500Lbs, much lighter than the Volt. If everybody is happy with Volt’s passing speed going uphill with depleted battery pack, then automakers should be selling more cars with sub-100HP ICE. Immediately we can reduce foreign oil import substantially. We do not have to wait for the Volt and other EVs and hybrids to reduce emissions and oil consumption.

G35X, You do realize that the Aveo only uses a tiny fraction of that 103 HP capacity over the life of the car, don't you? All of that extra HP is used for the "pep". It only takes about 20 HP to keep an average car moving down the highway. How often do you step hard on the gas (pedal to the metal) or go up a steep hill compared to how many miles of highway driving you do? If you look at the average (cost conscience) driver you would see that the full 103 HP is very rarely (if ever) used.

That is one of the main points of the Hybrid design. It can use a tiny ICE because the battery and electric motor can provide the "pep". Get it? Good! I think the average hybrid owner will be aware of the limitations when the battery is drained. They will not say, "Man, this car is a piece of crap." Then again, some people call into computer service centers complaining that the coffee cup holder is no longer working (Yeah, you know the part that says CD/DVD on it). ;)
 

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"The ability to actually use more than about 50 kW doesn't exist very frequently." – Larry Nitz, GM

GM’s smallest car, Aveo has a 1600cc ICE rated at 103HP (77kW) and weighs about 2500Lbs, much lighter than the Volt. If everybody is happy with Volt’s passing speed going uphill with depleted battery pack, then automakers should be selling more cars with sub-100HP ICE. Immediately we can reduce foreign oil import substantially. We do not have to wait for the Volt and other EVs and hybrids to reduce emissions and oil consumption.
Four points.

One, the Volt's ICE is only there to keep the battery at a state of 30-35% charge. It has been said that when the Volt enters range extension mode that the battery pack will still be available for certain surge situations, such as passing and climbing a short hill.

Two, almost never does anyone use 100% of the available power that the engine can provide in a conventional car now for an extended period. So the 50kwh power that the ICE can provide should cover 90% or more of ordinary driving needs.

Three, power transmission to the wheels should be more efficient than in an ordinary car, so that has a multiplying effect. 50kwh may be more equivalent to say 65kwh in an ordinary car.

Four, this car will probably not behave exactly as the cars we are used to now. It's all part of the transition phase to EVs. So yeah, acceleration up a hill in RE mode might kind of suck compared to what we are used to. Early adopters will have to adapt to new performance limitations.
 

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From Wired:

That's all well and good from an engineering and accounting perspective, but is a 1.4-liter engine big enough?
A 1.4L engine used at it's most efficient RPM should be more than enough power when you think about it. It may even be a bit big. you can't compare it to driving a car with a 1.4L engine since in regular driving you aren't using it at it's peak RPM.
 

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I know, I know. My point was if people can live with the performance of the Volt when it is going uphill in the limp home mode, then automakers should offer more sub-100HP automobiles. Immediately they can be one of the major contributors in reducing emissions and foreign oil dependency. Take the Japanese market, for example, last year they sold a little more than 5 million cars, vans and small trucks, of which about 2 million were so-called “kei car” class with 660cc engine, output of which is only 50HP or so.
Automakers have long been telling the consumers; the more power, the more desirable. Cost-wise a 1000cc engine and 1500cc engine are not so different. But, certainly they can charge $$$ more for the 1500cc model. The brainwashed consumers (myself included) must change their attitude toward the automobiles. The Prius, which is still a rather poor performer driving dynamics wise, was an eye-opener in this regard. Hollywood celebs happily wanted to be seen in it, even though they might still be keeping F-40’s, DB9’s, H2’s in their garage. The Volt can be the next Prius. Want to show off your status with the car you drive? Don’t worry, on weekends you drive to Hamptons, the Americana Shopping Center in Manhasset, marinas and golf clubs in your Escalades, 911’s and X-5’s.
 
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