Ack! Electric problem (blowing alternators)
Ack! Electric problem (blowing alternators) I finished my LS1 swap into a 1991 Z28 last summer, drove it all year, then put it up for the winter.
When My dad got it out this spring to take to a car show while I was out of town, he told me the alternator wasn't charging. Sure enough, the 80 amp fuse I installed in the alternator charge wire (battery is in the rear) had blown. I replaced the fuse to see what was what and I promtly blew the alternator. Replaced the alternator, traced all the power wires and didn't find anything obvious. Fired it up again today and it popped the fuse in the first 10 seconds.
I am not a wiring guy, so I have no idea how to track this issue down. Any suggestions?
Thanks in advance.
When My dad got it out this spring to take to a car show while I was out of town, he told me the alternator wasn't charging. Sure enough, the 80 amp fuse I installed in the alternator charge wire (battery is in the rear) had blown. I replaced the fuse to see what was what and I promtly blew the alternator. Replaced the alternator, traced all the power wires and didn't find anything obvious. Fired it up again today and it popped the fuse in the first 10 seconds.
I am not a wiring guy, so I have no idea how to track this issue down. Any suggestions?
Thanks in advance.
Let me get this straight... you're putting an 80Amp fuse on a 102Amp (Camaro), 110Amp (earlier Vette), 140Amp (GTO), 145Amp (Later Corvette), or 150Amp (Later Corvette Convt) alternator... and you can't figure out why you are blowing fuses?
I'm not just blowing fuses, I'm also blowing alternators.
No easy answers on this sort of thing. You have a short somewhere and need to find it.
Start with the obvious. Look over all your wiring for anything unusual. See if any wires have worn through and are shorting to each other or sheet metal somewhere. Look for any signs of arcing or overheating. Pay particular attention to anyplace where the wires are routed through sheet metal holes.
Beyond that get an ohm meter and start checking for short. I would also bring your battery in to be tested. Those can short out also.
Good luck
Start with the obvious. Look over all your wiring for anything unusual. See if any wires have worn through and are shorting to each other or sheet metal somewhere. Look for any signs of arcing or overheating. Pay particular attention to anyplace where the wires are routed through sheet metal holes.
Beyond that get an ohm meter and start checking for short. I would also bring your battery in to be tested. Those can short out also.
Good luck
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Brett Foote I believe I have to have some kind of short, but I have not found it by tracing the wires. Is there a procedure to check for shorts? I am certainly not an electrical guy, so speak slowly and use small words
No I didn't add a resistor, but it is a fuel injected swap (using the original pcm for the engine).
I believe I have to have some kind of short, but I have not found it by tracing the wires. Is there a procedure to check for shorts? I am certainly not an electrical guy, so speak slowly and use small words
I believe I have to have some kind of short, but I have not found it by tracing the wires. Is there a procedure to check for shorts? I am certainly not an electrical guy, so speak slowly and use small words
Here's a start:
1.) Disconnect that big batt-postive wire from the battery, and from the alternator. Don't wiggle the cable or otherwise disturb its position...if it's shorted, you want it to stay that way.
2.) Whip out your Ohm meter and probe the cable at the alternator end, with the meter's other probe (doesn't matter pos or neg for this test) probing a good ground.
3.) Report back with the meter reading. Should be no continuity whatsoever. Anything else indicates a short. I expect you'll get infinity on your meter, which indicates a dead short to ground.
Report back with your findings and we'll go from there.
I didn't know that, good point. I figured if that wire was open the alt wouldn't charge at all, similar to older applications.
1.) Disconnect that big batt-postive wire from the battery, and from the alternator. Don't wiggle the cable or otherwise disturb its position...if it's shorted, you want it to stay that way.
2.) Whip out your Ohm meter and probe the cable at the alternator end, with the meter's other probe (doesn't matter pos or neg for this test) probing a good ground.
3.) Report back with the meter reading. Should be no continuity whatsoever. Anything else indicates a short. I expect you'll get infinity on your meter, which indicates a dead short to ground.
Report back with your findings and we'll go from there.
Re-connected the battery cable, disconnected the small wire to the alt, checked for voltage with the motor running. Read 25 millivolts.
Last edited by tracar91; May 5, 2009 at 02:36 PM.
The premise someone posted previously makes sense...the fuse is undersize for the application, and when it blows it causes the voltage regulator in the alt to fail.
1.) The batt is in need of a nice slow recharge, having set all Winter without a battery tender on it. I like 2 amp charging rate for Optima gel batts. Don't overcharge it, just get it back up to a full charge.
2.) The fuse may not be sized properly. The battery at it's low charge state is likely pulling more current from the alt than the 80a fuse can take. Look up the max fuse size for the guage of wire you're running back to the batt, and install that. As stated above, the alt is rated at least 110a peak output so you'll need at least a 110a fuse.
3.) The voltage regulator in your new alt is toast. Swap in a replacement alt after solving #1 and 2 above.
1.) The batt is in need of a nice slow recharge, having set all Winter without a battery tender on it. I like 2 amp charging rate for Optima gel batts. Don't overcharge it, just get it back up to a full charge.
2.) The fuse may not be sized properly. The battery at it's low charge state is likely pulling more current from the alt than the 80a fuse can take. Look up the max fuse size for the guage of wire you're running back to the batt, and install that. As stated above, the alt is rated at least 110a peak output so you'll need at least a 110a fuse.
3.) The voltage regulator in your new alt is toast. Swap in a replacement alt after solving #1 and 2 above.
The premise someone posted previously makes sense...the fuse is undersize for the application, and when it blows it causes the voltage regulator in the alt to fail.
1.) The batt is in need of a nice slow recharge, having set all Winter without a battery tender on it. I like 2 amp charging rate for Optima gel batts. Don't overcharge it, just get it back up to a full charge.
2.) The fuse may not be sized properly. The battery at it's low charge state is likely pulling more current from the alt than the 80a fuse can take. Look up the max fuse size for the guage of wire you're running back to the batt, and install that. As stated above, the alt is rated at least 110a peak output so you'll need at least a 110a fuse.
3.) The voltage regulator in your new alt is toast. Swap in a replacement alt after solving #1 and 2 above.
1.) The batt is in need of a nice slow recharge, having set all Winter without a battery tender on it. I like 2 amp charging rate for Optima gel batts. Don't overcharge it, just get it back up to a full charge.
2.) The fuse may not be sized properly. The battery at it's low charge state is likely pulling more current from the alt than the 80a fuse can take. Look up the max fuse size for the guage of wire you're running back to the batt, and install that. As stated above, the alt is rated at least 110a peak output so you'll need at least a 110a fuse.
3.) The voltage regulator in your new alt is toast. Swap in a replacement alt after solving #1 and 2 above.
So in summary, I can eliminate the fuse (make is a solid wire from alt to battery), trickle charge the battery and replace the alternator (thank god for lifetime warranty
) and things should be all good?