Ok so I put an alternator on probably 7 or 8 months ago and things were fine, till about a month ago, the alternator went bad on me, no battery light ever came on, the lights just started to dim and the car died, first i thought it was the battery so changed that, then learned it was the alternator so i took it back and got a new one under warranty, a day after putting the new one on, the battery light was on, so i took it back, got my money back from autozone, and went to one of the local parts stores, i got another alternator from that store, put it on, and drove the car for about 2 weeks, until the battery died once again, again the alternator was junk, no battery light ever came on, so i took it back to the parts store, they gave me a new one, and before i put it on, i redid the grounds in the engine bay, cleaned the battery terminals, took out the old aftermarket stereo (which was wired very poorly by the previous owner) redid everything even soldered and heatwrapped it to make sure id have no problems with it, redid the power outlet in the dash, which had the wires cut for some unknown reason? (whoever gave the kid who owned this last wire cutters made a bad choice) so anyway after doing all the that i put the new alternator one, went out and drove the car for probably 20 minutes and the cel came on and it was flickering? then the battery light came on, now the battery light came on too, the battery has 14.5 volts while running and 12.6 when shut off and im just totally clueless, im at my wits end with this car, if anybody knows whatsup with it, please help

 

What is the voltage across the battery posts under high electrical load (high beams, rear window defogger, A/C max)?

What CEL codes are thrown?

 

Loose ECU connector? If I recall correctly the ECU controls the alternator and if there is a bad connection the alternator won't put out enough voltage to keep up.

If that isn't the problem, maybe you have a short somewhere. I would try to measure the current draw from the battery with everything off. If everything is off, there shouldn't be much draw from the battery. If there is a current draw then you have short on the non-switch power side. If this doesn't turn anything up, then start turning stuff on and see what starts drawing more than it should.

I think it's your ECU.

 

its at 14.4 with things off, 14.2 with everything on, and the battery is at 12.9 when the car is off

 

and im not sure of the cel codes, i havent got it checked yet, last time i got it checked it was on for an O2 sensor, im not sure if there are more codes now or not

 

Its like everything seems to be charging right, but that battery light is on and i cant figure out why?

 

Figure this out yet?

 

I have pretty much the same issue, except mine is with the brake light. It suddenly comes on and then goes off, and a while later comes back on, and my instrument panel light flash between full intensity and dim. For some reason, every time my alternator goes bad, it does that with the brake light. I've changed the alternator around 6 or 7 times in the last two years. Any ideas?

 

Check the fluid level in brake fluid reservoir and the switch in the lid.