AutoblogGreen

1. I alway's tought that. A small gasoline in-board battery recharger and booster is mandatory in a battery car. The car battery can be smaller and it weight less, weight is the ennemy of fuel economy( or battery depletion economy). A car need only 10-15 horsepower to maintain a speed of 60 m.p.h on the highway. I know it's the chevy volt concept but they never discuss their projected ice size. I think that 20 h.p can be sufficient. The electric motors must be on the front wheels too for efficient regenerative breaking.

Posted at 9:03PM on Apr 14th 2008 by A.Brien

2. Wasn't this idea called the Honda Insight? Which got canceled due to bad sales...

Posted at 11:00PM on Apr 14th 2008 by Mike Z

3. I fear that the automakers in the US are unwilling to face the implications of the pure EV or PHEV with small generator - that is, that their function will revert back to that of the coachbuilders of a century ago. Building electric motors and batteries are both specialty functions best left to suppliers. The small urban car that is needed for commuting is nothing like the mini-musclecar design of the Chevy Volt, but more like that envisioned in the MIT project, or the Loremo.

Posted at 11:02PM on Apr 14th 2008 by Bill S.

4. I've wondered myself why Chevy is using such a large gas engine just to turn a generator. IIRC, it will be 1.0-1.3 liters, which seems like gross overkill.

I'm no engineer -- maybe someone else here knows how small an engine could be for the purpose of charging the battery pack. Would a 250-500cc 2-cylinder be enough?

Posted at 11:10PM on Apr 14th 2008 by Wave54

5. The US auto industry Lives on selling you something you don't need: Horsepower. The large V8 is virtually the only component they invest in. Mahindra will not only be the first 4 cyl diesel hybrid on the market, but also the first 6 speed auto.

Posted at 11:22PM on Apr 14th 2008 by mike

6. The GM Volt's engine is large to support 'full performance' operation when the battery (40 mile range) is depleted. That's not a bad strategy for a vehicle that represents a transition.

Posted at 11:39PM on Apr 14th 2008 by Ron Fischer

7. >>6. The GM Volt's engine is large to support 'full performance' operation when the battery (40 mile range) is depleted.

Posted at 12:04AM on Apr 15th 2008 by Wave54

8. Ron,
GM's Volt is a serial hybrid, the gas engine doesn't drive any wheels, it only generates electricity. The point is, it doesn't need to be so big just to generate electricity.

Posted at 12:05AM on Apr 15th 2008 by mike

9. Hmm... blog doesn't like certain characters.

#6: Can you explain the term "full performance operation". The Volt's gas engine doesn't assist in propulsion, but serves to drive a generator to recharge the battery which powers the electric motor. That engine (1.0 liter+) is as large as the sole power source in many sub-compacts.

Does it have to be that large and powerful to generate enough electrical power?

Posted at 12:10AM on Apr 15th 2008 by Wave54

10. Let's do the math. The Volt's engine is 71hp. Let's say that after generator losses, it's only translating 60hp into electricity. That's 45kW. The Volt gets 200Wh/mi. These ratings are usually at 55mph, so let's say that at 100mph, you're burning 2 1/4 times as much energy (450Wh/mi) -- does that sound reasonable? That's 45kW. So, I would judge that the Volt's engine is sized to sustain a speed around 100mph.

Personally, I think that's way, way overkill. What percent of Volt owners do you think will ever even hit 100, let alone need to sustain it for a sizable length of time?

Posted at 1:25AM on Apr 15th 2008 by meme

11. Clarification: 2 1/4 times as much energy *per mile*.

Posted at 1:27AM on Apr 15th 2008 by meme

12. This concept (serial hybrid) is certainly not new, but waiting for an established automaker to bring one to market in the near future is not likely IMO. A sizable portion of our economy revolves around complex ICE engines (manufacture, support, etc.) as well as the massive amounts of fossil fuels required to power them. Large industries are beholden to the system as it currently stands by political and economic forces.

An ICE generator would be much, much smaller and could run at a continuous, optimal speed when needed to charge battery packs. Smaller, more flexible start-up companies like Aptera and Venture Vehicles will most likely show the way that the others will eventually have to follow...if these start-up can keep their heads above water and avoid the temptation to sell out to big business.

Posted at 1:59AM on Apr 15th 2008 by Ralph

13. The engine in the Volt probably doesn't need to have that much hp for regular driving. But what if you're driving really hard, or really fast for a very long time ?

I'm guessing that GM wants to make sure that the car will behave consistenly no matter how you drive it. But i still wonder why they need such a large engine. You can get 80hp out of a very small engine if you don't have to worry about torque. Think motorcycle engine, 2cyl, 500cc, around 70 lbs.

Posted at 6:25AM on Apr 15th 2008 by Laban

14. The size of the engine in Volt does not have anything to do with efficiency. Whether it puts out 20 or 100 KW is irrelevant ( apart from weight, but its a second-order effect in overall efficiency ), as long as it burns fuel at peak possible efficiency at all times and all that goes into battery.
Oversized engine is actually better, it just fires up, tops the battery off and shuts down again.
The best option would actually be a microturbine, stirling or a linear ICE.

Posted at 6:37AM on Apr 15th 2008 by kert

15. Well, it only takes a few HP to keep a car going at highway speed on flat ground, but hills are another story. Ever drive one of those VW Microbuses in hilly county? They just crawl their way up hills.

Given the situation with our (lack of) fuel supply, we should probably get used to that, but people have come to expect that cars will just zip up hills on the highway at 75 mph with no difficulty, even with a headwind. That takes a lot more than 10 HP.

A car that costs $40,000 and can't make it up hills on the highway is not going to sell well at all.

Posted at 7:01AM on Apr 15th 2008 by BlackbirdHighway

16. Blackbird, you hit the nail on the head. The engine could indeed be half the size it is but they're designing for worst case. Also I bet the cost to GM of a 50hp engine is little more than the cost of a 20hp, maybe even less because they would have to design the 20hp from scratch.
P.S. I owned one of those microbusses, 36hp. You had to climb steep grades in 2nd gear at 20mph, really inadequate performance.

Posted at 8:48AM on Apr 15th 2008 by Dave K.

17. Don't forget that the heat/ac is not coming from the gas engine. On a cold winter day with the heat on high, rear window defroster on, heated seats (maybe), at 70mph it will need the extra capacity. If it does not perform like a standard car, everyone will call it a pos, make fun of GM and the car will not sell in large volumes. They have to build the car to fit large numbers of people, not just one or two.

Posted at 9:06AM on Apr 15th 2008 by rar

18. I suspect GM choose the engine it did because they will be using that engine 1.0 (3cyl) in their micro cars like the beat. The 1.3 liter diesel in the Flexstream is probably a Fiat design. By using off the shelf engines they reduce the cost of a major conponenent, and reduce the time needed to develop the Volt. Makes good business sense.

Posted at 11:24AM on Apr 15th 2008 by Throwback

19. The Volt's Lithium Ion batteries are not toxic.
They are certainly less toxic than the lead acid batteries in all current non-hybrid cars.

Posted at 11:26AM on Apr 15th 2008 by TKG

20. "Oversized engine is actually better, it just fires up, tops the battery off and shuts down again."

Not really. You have startup losses, and probably more pollution in start/stop operation. Also, oversized engine means extra weight, which is a big problem for EVs/PHEVs.

Posted at 3:26PM on Apr 15th 2008 by KarenRei