Thanks for all the coments guys im starting to understand it now, i understand the loss could be less then the gain, but if the electric motor driving the vehicle only needs 12 volt 22 amp 264 watt, and the alternator would provide 12 -14 volt 90 amp, would this idea work if a lithiom ion or deep cycle battery rather than a car battery?
Josh, looking at the specs on devices can be misleading.
You're apparently looking at a specfic model design and specs (specifications) for your numbers, which I will accept at valid. So "
the electric motor driving the vehicle only needs 12 volt 22 amp 264 watts", okay, but that doesn't mean it
always needs 264 Watts. I'd guess that's a "cruising" number, the amount the motor needs to produce to cruise at, say, 55mph (just a guess) for long periods. If you go slower, like 10mph between stoplights downtown, it draws considerably less power (= less amps; Voltage remains more-or-less constant). If you're maintaining your 55mph up a steep hill, it draws
more power (=more amps).
So just for the first step, realize that the more mechanical work the motor has to do, the more electrical power it needs to do it. It's not a steady 264 Watts for all situations.
Moving on to the alternator, the
12 -14 volt 90 amp you see on its specs don't mean that spinning it will necessarily produce 90 Amps of current. What's listed on the specs is the output of the alternator
at a certain rpm (rmp = revolutions per minute, i.e., how fast it's made to spin.)
There is usually a voltage regulator involved that keeps the voltage a constant 12-14 Volts, but the amount of current produced will vary with the speed you spin it. You might spin it slowly with a hand crank and produce as much as (just guessing) 1 or 2 Amps, producing 12 to 24 Watts. It's going to take a lot more mechanical power, like with an electric motor, to get the rated 90 Amps.
If you ever get a hand-cranked alternator to play with, try this: Crank it with nothing hooked onto it to draw power. You can spin it up pretty fast when it's not producing any current flow (Amps) because it's not doing any work. When you put a load across it, like for instance a 4-Watt flashlight bulb, you discover you have to crank it a lot harder--producing current takes mechanical work. Producing
more current takes
more mechanical work; so if a 1-Watt bulb made you work hard, a 2-Watt bulb is going to give you hand cramps after a minute or two.
You've probably figured this out by this time: The electric motor you use in your car, running at 12V/22Amps (=264 Watts) can't supply the mechanical power it takes to spin the alternator fast enough to generate the 90 Amps (which, at 12 Volts, = 1080 Watts).
Hope that helps to clarify it for you.
I encourage you to continue to ask questions as ideas occur to you, and keep asking until you get answers that satisfy you. I also encourage you _
not_ to accept answers like "If it could be done, somebody would already have done it." That may be true most of the time, but the history of progress is full of examples where it wasn't.
I'd bet money that most or all of the experienced technical types on this forum have made some innovative improvment, sometime, to something they worked on over the years, because they
didn't think, "If it could be done, somebody would already have done it."
It's probably correct (just guessing) 99.9 % of the time, but if you accept that answer 100% of the time, you're going to miss some very rewarding moments in your life. So keep looking at possibilities and don't let them go until you get answers that satisfy you. Even if it isn't practical, you'll learn something finding out why.
And don't _ever_ let anybody tell you that all the good ideas have already been thought of.
