Alternator killer

[LGAFF]

Replaced the alternator on my 92. Within 2 minutes it was toast also; battery light came on, volts dropped. I had a battery tender unit on the battery(one you install on the batt and leave it),once I took the tender off, restarted the car, the light came off....but its producing only 12.2 volts.


hmmm any ideas...could the batter tender wiring be killing my alt....

What a PITA....

[Jagdpanzer]

Can't see how a little trickle charger could wipe out a 120 amp alternator.
If the alternator is not putting out it was probably defective from the get go.

[GOLDCYLON]

Can't see how a little trickle charger could wipe out a 120 amp alternator.
If the alternator is not putting out it was probably defective from the get go.

Concur it's not a trickle charge battery tender that's the problem. You also might have an internal cell short within the battery

[scottfab]

Replaced the alternator on my 92. Within 2 minutes it was toast also; battery light came on, volts dropped. I had a battery tender unit on the battery(one you install on the batt and leave it),once I took the tender off, restarted the car, the light came off....but its producing only 12.2 volts.


hmmm any ideas...could the batter tender wiring be killing my alt....

What a PITA....

Some troubleshooting needed. Not likely a battery tender at fault.
1. does the battery when disconnected from the car charge up ok?
If a cell is shorted then the pull from an alternator will be outrageous.

2. Assuming battery is ok, what does the field winding voltage go to when the car is running? (small wire pair going to alternator) Could it have been pinched or cut etc? If no 12v on the field winding you car rig a test by disconnecting the connector and supplying 12v straight from the battery. With the car running if the alternator is good it'll pump out about 14V.

You're likely going to have to pull the alternator again. The good news
is you've just done it so it'll go fast. Have it tested (free at O'riely's and other car places as I'm sure you know)
There has to be a warranty on the thing.
Good luck guy.

[LGAFF]

The battery is new, will have to do some testing....its odd that when I took the tendering wiring off, the batt life no longer illuminated. I have my old alternator off, will have that one test also to see what the issue is...

[GOLDCYLON]

The battery is new, will have to do some testing....its odd that when I took the tendering wiring off, the batt life no longer illuminated. I have my old alternator off, will have that one test also to see what the issue is...

Lee get a load test done on that "new" battery as well

[LGAFF]

Alt output is "0"

[scottfab]

Alt output is "0"

but if the signal from the car (alt control pair) is zero
then the alt could still be ok.

[-=Jeff=-]

Alt output is "0"

Was it tested? How do you know this for certain?

I had an issue with my 89 where one of the Alt wires going back tot he battery broke, causing me to think the Alt was bad when it was a bad/broken wire

are you sure you don't have the wiring shorted anywhere?

[LGAFF]

I tested the prior alternator it was definately bad. I tested this one on the car, the car is running completely off the battery. I am just wondering if there could be a short killing the alternator; what are the odds of two in a row? I would think its unlikely as its the 92(24K miles) and nothing changed on the car.

Alittle puzzled.

[-=Jeff=-]

Time to crack out the DVM and start checking things

[Schrade]

but if the signal from the car (alt control pair) is zero
then the alt could still be ok.

Yup - sure could. I always thought that if the alternator was turning, it was outputting juice (if working properly).

Such ain't the case.

I had a BAT light on my '94 once. Put a multimeter on the Field Output on the alternator, and got no reading. Bad alternator - right?

Put on a new PREMIUM built unit, and didn't even test it (wasn't a daily driver).

Couple days later, was in the mood for a cruise, and pulled the trigger. BAT LIGHT. HUH?

Chased EVERYthing with a multimeter for 3 1/2 hours, then a buddy at Advance said maybe a fuse is popped. Can't be, I said.

Ain't the first time I was wrong, probably won't be the last either.

[LGAFF]

Problemo solved,although the bat wire connector was firmly crimped to the insulation, but it had cracked and bent and no longer contacting the wire. I replaced the connector....14.4 volts:)

[scottfab]

Problemo solved,although the bat wire connector was firmly crimped to the insulation, but it had cracked and bent and no longer contacting the wire. I replaced the connector....14.4 volts:)


Good to hear. Another ZR-1 back on the road.:-D

[GOLDCYLON]

Good find Lee electrical crap drives me bat crazy

[LGAFF]

GC, I had an 87 with a battery drain about took apart the entire car, ended up being the dash....I am challenged in the electrical dept.