Injector and alternator wiring question

[parsonsj]

Frank at ProdigyCustoms finally figured out the story on my alternator: I need to turn it on via switched power (the green wire ... who knew?).

Anyway, figuring that out begs some new questions.

First, anybody see a problem if I were to hook into the injector sub-harness and use that switched power to also switch the alternator? Or is that a bad idea due to possible circuit feedback problems?

Also, any problems anybody can see about battery drain here? If the excitor circuit is turned off via the switch, would I have a problem with the alternator draining the battery while the car isn't running?

thanks!!!
jp

[gmachinz]

Jp, I don't see an issue running your excitor lead off your injector harness-if the alternator excitor lead power is shut off (I assume by ignition, off...) then there isn't any way it could drain the battery through that circuit. As for feedback or the possibility of any current travelling back through to your injector harness, use a tamping diode between the harness and the alternator lead-this way, the current can only travel in one direction and and feedback won't be an issue for you. Just for the sake of simplicity, why not just run a relay off the ignition dedicated for the alternator excitor circuit? We're not talking about a lot of current anyway, are we? I'd leave the whole circuit out of the injector harness altogether but if you go that route, be sure to use a tamping diode inline. Curiously, what kind of alternator are you runnin', JP? A 1-wire with 3-wire features perhaps? -Jabin

[parsonsj]

Jabin,
The brand name of the alternator is Race, Inc. Try searching for that on the web! The engine builder (Wegner Automotive Research) supplied it, and it is a quality piece. It just didn't come with any documentation, and I never quite figured it out. Frank sorted it all out for me this morning. Yes, you switch it on, and it makes 100A. Switch it off for minimum drag. Pretty cool, nicely packaged, but a PITA since I didn't allow for all that in my harness. I do have one extra wire available from the power connector that drives the driver side injectors though.

Where might I find such a tamping diode?

jp

[Van B]

Here is the alternator manufacturer's website. http://www.raceproven.com/ ,not real useful at this point.

I guess there were some advantages to getting the car running up at Wegner's shop. I just had to go ask Casey which wire was the exciter.

JP I'll be down there next week. PM me a phone number so we can try to catch up with each other.