I already answered that question above... But I'll try again. The amount of gasoline used to prodduce electricity thru the alternator can be used to power the vehicle farther than that amount of electricity can.... So there is a LOSS of gasoline in that usage.

If it WAS POSSIBLE then a simple 2 stroke generator could power the vehicle..
Energy used to make energy in ANOTHER form is energy LOST!

I believe it is Honda that has a test vehicle that produces electricity from the BRAKES of a vehicle.. So while stopping the vehicle is charging a battery to help with the lectric car motors.
BUT It takes more energy to get the vehicle up to speed with the extra weight.. So far they are operating THAT system at a loss of gasoline energy.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

The think the Prius uses breaking to charge the batteries also. I believe it works as a motor/generator by switching the field. While it has been stated you cannot get a NET GAIN in energy, this is different because instead of the energy produced and wasted in brakeing on a normal car (heat), switching the motor to a generator allows resistance caused by the generator to slow the vehicle, taking back some of that energy. Still a net loss, but less of a net loss. There are no extra parts other than electronics so i doubt weight is an issue.

Different than burning gas to load up the alternator to perform the electrolosis needed to split H2O. By the way, most hydrogen production is a result of reacting natural gas with high temp steam. Byproduct CO2 and CO. So those "no-emission" hydrogen cars get their fuel from another fuel we could use, while the production of that "no emission" fuel causes just as much greenhouse gas emissions (if not more when you add in the fact that something has to heat up all that steam, Bob and Hank drive their cars to the plant, energy put in for compression of the H2, sequestering of the CO2, etc.

Josh

Too bad we can't run cars off of the hot air,co2,and bs(methane?) that the gov't dishes out on a daily basis. that would be free and unlimited forever

Keep in mind that if there is not a great deal of demand on the alternator, then it doesn't take much engine horsepower to turn it. But if there is a large demand (big stereo system, depleted battery, off-road lights, winching, etc.), then the alaternator will offer more resistance to trotation, and thus will require more engine horsepower to turn it.

If the vehicle's battery is fully charged, and no major accessories are running, then it takes very little engine horsepower (and therefore gasoline) to turn the alternator. Not so when it's really working.

How does it's rotational resistance change? I thought it's basically an electric can motor being turned by the engine, so the resistance to passing the coils of wire through a magnetic field would be constant whether the there was demand for the electricity produced or not??

I don't completely understand what goes on in there either.. BUT I do know that it takes more energy of one type to make more energy of another type. I just always understood it took more fuel to make 80amps than it did to make 5 amps..
Since it is done with magnetic force maybe as the amps get higher so does the magnetic force, causing the alternator use more HP to turn it????
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

On any generator (or motor for that matter), as the load on the generator/alternator increases, the current in the windings increases. Therefore, it takes more force to produce the supplyfor that load. On an engine-driven generator, that means it takes more horsepower to turn the alternator.

As Grandpa said: "You can't get something for nothing!"

BJ,

As the load (current demand) on a generator increases, more Counter-EMF (Electromotive Force) is developed, and it requires more force (horsepower) to overcome that greater Counter-EMF.

Thanks for the explanation. I never did too well at the electro-magnetic section in physics class. <img src="/forums/images/graemlins/cheers.gif" alt="" />

My thinking was a bit different since I never got to a physics class..A Redhead got in the way..

I was taught as a youngster that there isn't a "perpetual motion machine" ie. a machine that will run itself.

Knowing this it falls into place that using one type of fuel to make another type of fuel one will lose power in the exchange.

SO: Using gasoline to make elecrticity, the lectric output will accomplish less than that same amount of gasoline could accomplish.. Meaning the task should have been done with the gasoline in the first place.

But thanks anyway for the explaination..
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />