Alternator backfeed discharge

[Carls_jeep]

Last spring when I rewired the Jeep and got it running I put a diode in the trigger wire to the alt. as suggested. Lately I have only driven it a few miles a day and began to notice the starter was a little slower so I checked the battery voltage, hmm, 12.7v. Then I put a Milliamp meter in the circuit and it was draining the battery at 3.67 ma., hmm. So, I ruminated on it for a few days deciding what could be draining the battery and the only thing I could think of was the alt. so I tried pulling the #1-2 plug on the alt. while checking the drain and that did it. I already had a diode in the #2 trigger wire so I tested it and it was ok. Then I tried disconnecting the #1 wire from the output post and that killed the discharge. Well Bubba said I, lets put a diode in that wire too and I did and it cured the problem.

Now, to be honest, the problem could be internal in the alt. but the alt. is working so the two diodes serve a purpose to isolate any backfeed issues. I am posting this in case anyone has noticed their battery discharging and wondered why. �

[Doug]

The alternator is supposed to have an internal diode that prevents the discharge to ground. �Three wire alternators usually hold up pretty well because they usually have a better quality internal diodes. �The typical one wire alternators sold, including the one wire conversion kits, usually contain a very low quality aftermarket diode. �The one wire alternator diodes fail very quickly. �I had two fail in 6 months. �I switched to a rebuilt three wire, lifetime warranty, delco remy and the diode is still working fine after two years. �

If you alternator has a warranty, you may be able to get it replaced free. �If you get a replacement alternator, watch the warrantise. �Often a new alternator has a one year warranty while a rebuilt alternator of the same model gets a lifetime warranty. � Last time I bought one you could get a 60 amp three wire delco remy with lifetime warranty for about $45 at Autozone.

[Carls_jeep]

It was on the Jeep when I bought it and I don't want to bother the fellow I bought it from and the Jeep was in another state anyway.

I figured it was a defective internal diode and since any alt. can have that failure I decided to post the fix in case anyone else has it and wants to stop the discharge. The best way would be to have the alt trigger circuit on a separate switch on the ign sw. but original switches don't have two switch circuits in them.

When I got the Jeep it had a removable positive cable end at the battery and I left it there. Now I know one reason he may have put it on the Jeep. Another is it's not a good idea to leave the battery connected through long storage and I don't think he drove the Jeep much other than the hunting season.

I bought a fuse block and terminal strip and this winter I plan to rewire it so things are fused. I still have an issue with the headlight sw. shorting out at times and tripping the breaker. Since I can't find a NOS headlight sw. I will use a toggle sw. for the headlights/tail lights.

[Bob W]

Isn't the #1 terminal the one that gets the diode? Yours was originally in the #2 wire?

[Carls_jeep]

Opps, I meant the diode was in the #1 wire per the wiring diagram I found, sorry 'bout that. I am guessing a diode in the #2 circuit inside the alt. is failing because when I disconnected that wire alone the discharge stopped. That's why I put a diode in both wires.