[petek]

DV,

How does current flow "both ways" whey you jump a car? Same sort of thing is going on.

With the alternator once the engine is spinning fast enough, the alternator is producing enough electricity to keep itself going. So initially the current is flowing from the battery to the field winding of the alternator, when the engine spins fast enough the voltage produced by the alternator is high enough that the current flows the other way (into the battery).

I wouldn't think there would be a problem at all with replacing the alternator on your car with a one-wire one. The ECU just won't control the voltage any more. If you wanted to get real tricky you could probably fake out the ECU by modifying the signals from the current alternator. Bring the standard voltage up to say 16 volts. Of course you'd need to replace the battery with a 16 volt battery!

I had an alternator go out on my car ... happened the same day my father was visiting. Car ran like poop when the ECU was running on battery power only. Charging the battery up before a run helped a LOT. Funny how things like the spark box and FI control don't like low voltage.

Interestingly the spark box (Holley) is designed to work with up to something like 24 volts! I don't know how many more joules would be produced with 24 volts, but I'm guessing you could arc weld with the spark controller box!