Bad Battery? Or Alternator?

[monoblanco]

Battery would lose charge. I took it back to Autozone, they tested it, told me it was good. If I started the car using jumper cables the car would start. Engine would die son after I removed jumper cables.

I concluded my alternator was bad.
Replaced it.
Took battery back to Autozone before starting the car. They charged it.

Car does not start.
No power, even though the battery reads as it should in my multimeter.
I can jump start the car, but the engine dies soon after I remove jumper cables.

Thoughts?

[TobyB]

Bad connection somewhere. Maybe grounds?

What car do you have? Trobleshooting depends on where the battery is...

t

[monoblanco]

That doesn't sound so terrible.
When you say bad connection, you're thinking battery connection?
I wonder if the alternator I just replaced was bad at all.

My engine is an M42.
Battery is under the bonnet.

[TobyB]

I'm thinking at the battery, where the lug meets the cable... or the charge wire meets the
lug... or the alternator lug attaches to the charge cable.

Or the grounds- same deal- check both ends of the ground cable,
and then make sure the engine is solidly grounded to the car. ESPECIALLY if you're
attaching your ground cable to the body, like one should...

hth

t

[nickmcc92]

Just unscrew the voltage regulator on the alternator and check it. Should only be two screws holding it in. If the lead part is almost gone. There's your problem.

[WhyNot]

Battery would lose charge. I took it back to Autozone, they tested it, told me it was good. If I started the car using jumper cables the car would start. Engine would die son after I removed jumper cables.

a battery losing a charge is different from a battery that runs down bc its supplying all the juice and the charging system isn't. i think that once its running you could disconnect the battery and the car should still run.
so that sounds like something in the charging system.

I concluded my alternator was bad.
Replaced it.
Took battery back to Autozone before starting the car. They charged it.

Car does not start.
No power, even though the battery reads as it should in my multimeter.
I can jump start the car, but the engine dies soon after I remove jumper cables.

a multi meter doesn't test a battery under a load. you could have a battery that supplies very low amps but it cant crank over the engine.
it almost sounds like two problems, a battery and something in the charging system.
can you switch out the battery so you can get the battery cranking the engine without a jump?
Also where are you jumping it? at the battery or under the hood?
once you get it cranking, it should run even if the charging system is bad.
once its running test the volts at a high idle, it should be higher than the battery volts, probably about 13-14 volts.
then with it running remove the a battery terminal and it should keep running.

[Jaxx_]

You need to double check all connections. I would treat the two issues as the same. If the battery won't charge and it won't keep the car running it's possible the load isn't able to be sustained whether charging or draw.

Where are you jumping it? at the battery terminals?

Check:
Battery posts and terminals
Battery cables to termination points
alternator battery positive terminal
starter battery positive terminal

I would also inspect the alternator exciter circuit if you haven't already. It's worth looking at so you don't chase your tail.