alternator low battery charge 94 q45

[djuneek]

i got a low battery charge warning and the brake light and tcs light ect .. then the alternator died. I got one from the junk yard, took it to autozone and it tested good. I have a new battery that tested good to. Now when I turn the key on without the engine running it says low battery charge and when I start the car with the engine running it says ok. Any reason this would happen. thanks

[Q451990]

What is the voltage at the battery terminals with the car off and then on? I would expect to see about 12VDC when the car is off and somewhere around 14VDC at idle. My guess is that the battery isn't fully charged, but the alternator is picking up the slack once the car is running. If you don't have a multi-meter, they are very inexpensive now. I have seen them for a few dollars at http://www.harborfreight.com

Heath

[djuneek]

12.3 with the car off 11.7 at idle and 11.3 with all the lights and heater on

[Q45tech]

Used Alternator is not functioning correctly. Probably one or more of the 3 parallel circuits have failed.

Not sure Autozone can fully test a non installed in vehicle alternator?

[maxnix]

Used parts that are wear items are a crapshoot.

Why you should get a Nissan remanufactured alternator form Joe unless you love getting under the car and doing that lovely job often.

http://www.infinitipartsusa.xom

[djuneek]

ok so after a week of driving the battery is still at 12.3 with the car off 11.7 at idle and I noticed if I rev the engine it jumps to over 14.5 and it stays there even with all the lights and heater on and stereo blasting. Is it still a bad alt or could it be anything else. thanks

[Q45tech]

You must load test the alternator to see that it conforms to oem ampere vs rpm specs.

The ecu is designed to see 13.2 volts engine running even at idle.

Common for old alternators to lose 1/3 or 2/3 of current capacity before final failure.

[djuneek]

i looked under the car to check the alternator and the plug was not clicked in. i pushed it in and it works good now. no more message and 14.5 at idle.