Can an alternator draw from battery overnight?

[garyohv]

"I have heard that faulty diodes in the alternator can draw back. However, wouldn't that also mean that the alternator wouldn't charge?"
NO, if there is a "short" in the alternator's "rectifier" diode pack, of 4-6 diodes, it (the diode) will work perfectlly half the time. The output would be "dirty"... with some ac. Bearable to a battery and bulbs, and fixed when propertyly recharged. When engine/alt. is off, this shorted diode will continue to flow electricity drawing down battery. Measure the discharge rate, disconnect the combiner, then the alternator, looking for the current draw.

[El_Guero]

Originally Posted by Wraith_Mac

El Guero,
The OP said in the initial post:
"I have tested the battery (which is just 12 months old) by disconnecting the leads over night & have also used a load tester on it. It appears to be holding full charge."
Cheers,
Mac

Missed that.

It can still 'be' the battery ... I have had one internal short on my life, it was a BEAST to finally find that problem.

[gspeak]

I got around to removing the alternator on the weekend & the auto electrcian declared it dead with multiple problems. He did say that it wasn't leaking but it also wasn't charging at all. I was there when he tested it on his test bench.

After pulling it down he said it wasn't worth repairing as it had already been done before & there were multiple problems & it appeared to have had a hard life. Not surprising since ours is an ex-charter Lagoon 380 with nearly 7,500 hours on the motors.

Anyway he has tracked down a 110amp alternator (to suit a Nissan 4WD) with the same mounting configurations & said that it will do fine.

The problem is I know the main Bat terminal is for the positive leads, & the Tee shaped plug is there also, but the lower terminal with 2 wires from the wiring harness on the old Hitachi is a mystery to me & doesn't exist on the new replacement. The auto electrician said that it was a 7 volt neutral for the Tacho etc & he wired a lead into the new alternator to provide this.

I do trust the electrician as he is very experienced, but can anyone confirm this before I hook it all up? I would hate to blow a brand new alternator or anything else.

Thanks

Dave
Seabreeze L380 #241

[hpeer]

See if this helps

[gspeak]

Thanks for that. However, none of those look anything like the original Hitachi 80amp setup.

Will try to take a photo on the weekend.

Dave