Thread: Alternator Mods
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Old 06-07-2009, 10:57 AM   #40 (permalink)
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Originally Posted by 1GCRXHF View Post
The "friction" in the alternator actually charging is the magnetic resistance the active circuit is supplying. The resistance is the current voltage the battery sitting at in the circuit. Generators (like your alternator) and electric motors are the same thing, the difference is the polarity of the circuit. If you hook up your alternator straight to your battery it will run; The engine has to overcome this force in order for the alternator to charge the battery, because it actually has to spin the alternator the OTHER way, in order put the battery in a charging state. I think the only way you could get less resistance from the alternator running would be to go with a low amperage unit. Adding a larger output alternator would be the exact same as installing a larger electric motor for your engine to fight. If you did your wiring right and went minimalist on your electrical goodies, you could easily get away doing this. Take a good look at anything that uses electricity in your car, and remember that every single milliwatt you is energy derived from your gasoline. Use less power, use less gasoline.
There seems to be a flaw to this logic. An alternator is NOT a generator. It has no permanent magnets. It is very similar to an induction motor, such as what you would find on a vacuum cleaner. But when there is no power going to the field coil, there is no magnetic resistance, only frictional resistance. And the alternator only draws its max output when the field coil is strengthened by the regulator.

Instead of alternator mods, worry more about reducing the electric load, as he pointed out. An alternator is designed by manufaturers to be very efficient, but the electric loads are not entirely efficient.

If you want to reduce the alternator load, put in a bunch of solar panels on the roof and dashboard.
RIP Maxima 1997-2012

Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.

Last edited by ShadeTreeMech; 06-07-2009 at 11:08 AM..
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