electric cars

[renovation]

I know they keep talking one day-electric in everyones driveway. But what I've been reading on them states that they for the most part will only go like 250 miles between charges. Why can't they make these cars self charging? I know in todays gas powered cars we use alternators to recharge the 12 v. batterys. Why don't they design alternators that can recharge the batteries in a battery powered car? Or what is the drawback of this being incorporated in them? I'm lost as to why this has not been done. Is there a design flaw in the batteries on these cars that they can't drive and charge at the same time? Any ideas-I really don't see where the problems would be.

I can see where smaller battery might be able to used if you could charge the car as its driven. Plus cutting down on the cars total weight.

[Daedalus]

They are self-charging, to some degree. Regenerative braking (also on the Prius) recovers some of the kinetic energy of the vehicle as the car slows down. The Prius gets better MPG in town than it does on the highway. But the energy recovered to the battery cannot be more than the energy available, meaning some is lost each time energy is converted. In truth most of the kinetic energy is still lost as heat. Recovery systems will probably get better, but for maximum range, I expect most increases will come from improvements in batteries and the amount of energy they can hold. The latest lithium batteries can hold a more energy/pound than Ni-MH, but the challenge has been getting them to discharge the energy fast enough. Lithium batteries don't have the memory problem that nickels do and can be charged without being discharged first. The Prius is slated to move from nickel to lithium batteries, but it's only a hybrid and probably doesn't need as good a discharge rate as a straight electric car. For most driving habits 250 miles range is more than adequate. The real upside is electric cars are expected to cost 1-2 cents per mile to recharge. Even a Prius costs around 5 cents per mile in gasoline. Next question is how cheap the batteries will get and how many years/miles they can go before needing replacement. I'm keeping my eye on these guys: Tesla Motors

[Cheesypuff]

I recommend you people watch the doc, "who killed the electric car" GREAT doc, and very informative.

anywho, what renovation is talking about is almost like a perpetual motion machine. you can build a car that puts energy back to the battery with enough efficiency. it breaks the laws of physics.

[InfiniteNothing]

I know they keep talking one day-electric in everyones driveway. But what I've been reading on them states that they for the most part will only go like 250 miles between charges. Why can't they make these cars self charging? I know in todays gas powered cars we use alternators to recharge the 12 v. batterys. Why don't they design alternators that can recharge the batteries in a battery powered car? Or what is the drawback of this being incorporated in them? I'm lost as to why this has not been done. Is there a design flaw in the batteries on these cars that they can't drive and charge at the same time? Any ideas-I really don't see where the problems would be.

I can see where smaller battery might be able to used if you could charge the car as its driven. Plus cutting down on the cars total weight.

If I follow you correctly, the answer is: the second law of thermodynamics.

[ramazank2]

I know they keep talking one day-electric in everyones driveway. But what I've been reading on them states that they for the most part will only go like 250 miles between charges. Why can't they make these cars self charging? I know in todays gas powered cars we use alternators to recharge the 12 v. batterys. Why don't they design alternators that can recharge the batteries in a battery powered car? Or what is the drawback of this being incorporated in them? I'm lost as to why this has not been done. Is there a design flaw in the batteries on these cars that they can't drive and charge at the same time? Any ideas-I really don't see where the problems would be.

I can see where smaller battery might be able to used if you could charge the car as its driven. Plus cutting down on the cars total weight.

The gaseoline combustion engine is what drives the alternator to charge the battery. In purely electric car the battery is charged and it runs out as you drive as opposed to the gas that runs out. You need some kind of energy to run a car. Sounds like you are talking about a perpetual motion vehicle, which is theoretically imposible.

[DarkFury]

The gaseoline combustion engine is what drives the alternator to charge the battery. In purely electric car the battery is charged and it runs out as you drive as opposed to the gas that runs out. You need some kind of energy to run a car. Sounds like you are talking about a perpetual motion vehicle, which is theoretically imposible.

Basically you said what I was gonna say...

[renovation]

maybe so im talking - what Sounds like you are talking about a perpetual motion vehicle, which is theoretically imposible.
why could you not have a axle or gear work as a pulley /gear and drive a belt to run a alternator to keep those batterys charged . so it use a bit of horse power / tork . seems this would enable you to make it all work .just the power companys be out some extra revnue ?

[InfiniteNothing]

Second law of thermodynamics. It takes energy to power an alternator and the alternator can't generate more energy than the energy it takes to power the alternator.

[bachviet]

Energy can't be created or destroyed. It could only be transferred from one form to another.

[InfiniteNothing]

Actually, if that were the only law around, his invention would work. It would simply get a push and roll forever because its kinetic energy couldn't be destroyed.

[Cheesypuff]

even tho Energy can't be created or destroyed. It could only be transferred from one form to another. there are many other factors that add into where the energy goes. 100% of the energy can never go back in the battery.

[mechmike0034]

http://www.gm.com/company/onlygm/fastlane_Blog.html#EV1

GM and Honda both tried full electrics with regenerative braking but, as stated, you can't "break" the laws of physics.

Hydrogen and fuel cell technology will be the next "holy grail"...

[dsuds]

Discounting the "perpetual motion" idea... renovation actually makes a valid point. Why can't electrics self charge? There are some areas where the electric-gas hybrid has advantages.

1. The charging motor runs at a set rpm, set load. This lets the manufacturers tune the motor for best efficiency. This is the opposite of current engine design that tries to be great at everything. By removing the "do-it-all" design constraints, I'd bet the efficiency could be raised from 30% (maximum for gasoline engines) to almost 40%.

2. By using the batteries to supply only the extra power needed for acceleration, the internal combustion engine can be much smaller. Most cars need less than 15hp to run down the highway, so why use gas engines that are over 200hp? Just make the motor big enough that you don't run the risk of starving the battery system. A small 1-2 cylinder motor is all that's needed.

3. Who says it has to be an internal combustion engine? External combustion engines are widely known to be cleaner and more efficient than internal combustion engines (Sterlings have been built that are over 60% efficient). The big reason we haven't seen these engines used is because they do not function well in the varying rpm, varying power world that the IC engine fit so nicely, until now.

In my opinion, a Sterling engine running at a fixed speed & load, charging a small stack of batteries, could produce a very drivable car. The car would have a lot of the driving characteristics of an electric, but not the range limitation. And it could very well break the mythical 100 mpg "barrier".

Dave

[Houdini]

Interesting reply above. And having small gas engines works for hybrids for the very reason people have mentioned. You can't use a finite amount of energy to generate more energy. If you could run a pulley with the car's electric motor, you'd only get a small percentage of what you're using to run the pulley back. So it would actually decrease running time. Newton was right. Otherwise, perpetual motion would be the result, and we could get off any imported oil and use domestics or even small amounts of imports to make oil-based-products, like plastics, etc.

[brainsmile]

Tesla is great but the price is hard to swallow

[Cheesypuff]

flux capacitor.........fluxing