ok i just got a new alternator and a battery and i upgraded to 130amp and did 4gauge wire but i noticed when at idle my car runs arround 13.5v and when i turn my lights on and heater and defroster it hits 12 and when i have just lights its 13.4 my question is there has to be something wrong since my friend has a 5.0 and his stock alternator runs at 13.8v i have 2 alternators at 130amps and tried both samething im not shure what it could be. i have a 4gauge power wire connected also. what could cause a power loss? i think maybe a short in a wire or something? also i tested the alternators at kragen and were in working order.
Alternator question
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goldbomb79 said:
4 gauge wiring is fine, just be sure to include the fuse inline with the 4 gauge wire.
As for the low voltage output, I would try using a digital voltmeter with one lead on the alternator terminal and the other lead on the positive battery post. More than .5 volt drop indicates a bad connection. Sometimes the crimp on connectors will get oil inside them and cause problems.
Make sure your ground is good. I've seen this too many times as a result of a bad ground. Also raise the idle a bit to like 1500-2000rpm and then see where the voltage is. This is to simulate normal driving. Just some things that might help.
whitehorseupnorth said:
He's right about that - you should have a 4 gauge ground lead from the block to the same place the battery grounds to the chassis. The engine ground from the back of the engine to the firewall is too small, and it is often missing or damaged.
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