Alternator Problems

[Green67Alpine]

Hello Sunbeamers,
On the way back from our South Georgia cruise in, noticed the alt. warning light was on at higher rpm, out at idle. (Stock Lucas 10 AC alt.set up) Not far from home at the time went there, lifting the bonnet I noticed sparks(engine still running) by the battery cable on the alt, turned everything off disconnected the battery and started poking around, aside from BOTH alt brackets being broken, the battery to alt cable had come off the terminal and had been grounding out on the terminal(battery) and case of the alt.
Now, I've replaced the brackets, checked the alt wiring harness( it's good).Hooked every thing back up and it's still doing the same thing, checked the battery Volts while engine running and get 14.5 not running 12.3 checked the 3AW relay (coolcat sub) it was cooked, replaced that but not started it up in fear of cooking it or something else.
Had the alt out to get tested, NAPA, and Advance auto can test it in the car but I'm not sure if I want to drive to the store.

Any suggestions, aside from the Alt upgrade. I like the "stock" approach.

Thanks in advance, Tom j

Come to the Invasion join in get involved......have a pint

 

[Ken Ellis]

Just so I understand, the sparking was from grounding the wire from the alt to the batt (shorting the batt + to gnd), or grounding the output of the alt (shorting the alt + out to gnd)? I suppose it's possible the alt was reverse-connected if there were times it "bounced" totally free of the car, and the alt frame was energized positive... but that's pretty unlikely.

I would still opt for "remove and test", just to minimize variables.

Ken

 

[Tom H]

I have the same question as Ken. It's unclear which end of the Battery to Alt cable was loose and shorting ? The battery end (thus shorting the Alt output) or the Alt end (thus shorting the battery). I'm guessing it was loose at the Alt end.

But regardless, when you ran the car the voltage looked like normal charging, so it looks like all is OK - Except the warning light, which is controlled by the 3AW, which you found to be defective and have replaced. Sounds to me like problem solved. I'd start it up and recheck voltage with car running and all lights and blower running, to be sure the Alt has enough output.

If the loose cable was shorting the Alt output, it could have damaged some of the internal rectifier diodes and now have less capacity. But if the loose cable simply shorted the battery, then not likely to have harmed the Alt.

One more suggestion - use some clamps and/or cable ties to hold the the alt to Bat cable tightly to the alt so it doesn't vibrate loose.

Tom

 

[Chuck Ingram]

It almost sounds as a diode in the alternator was gone.It would show
14 +volts charging at an idle but under load it would not really charge.
I would opt for having it out and bench tested at an Auto electric shop and not at a retailer.R and R is not hard or take much time at all.

 

[Green67Alpine]

Ok, The "big brown" cable from the solenoid to the alt was the culprit,since then it's got an eye fastener instead of the push on 'shoe'. I'm sure it will never fall off again. while it's out a trip to the auto electric shop is in order.
THANKS, Tom j

Invasion X coming soon! ! !!