Battery light coming on

[naiku]

About a week ago my battery light flickered on for a second then went off. Since then I have driven around 200 miles and the light had not come on since, in the meantime I checked my battery voltage (with the engine off) and it was reading 12.4V. Today I took a short drive and almost immediately the battery light came on again, solidly at first, then flickered a few times, then eventually stayed off. All within about 8 miles of driving, the car sat for about 3 hours and then drove home and the light did not come on at all.

Is there a way to check the alternator? I need to check the battery with the engine running, but with it off the battery (which is only about 5 months old) appears to be good. Any other suggestions?

Thanks.

[pezgoon]

Take it out? I'm not sure if there is another way to check it while running.

The battery is really only 5 months old? Id maybe swap it out (warranty). Batteries can fail lol


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[aluthman]

Possible alternator issue also. You need to check voltage with the car running. I think autozone can check it for you to see if it's charging.

[vce1232000]

the positive terminal while engine is running. If it stalls out the alternator is charging

[naiku]

Just took some readings, 12.4v with the engine off, engine running 14.7v, engine running, lights on, a/c on full and stereo blasting it dropped to 13.9v.

So everything looks good there, the car is likely to sit now until Thursday so will be checking battery voltage to see if it goes down any while sitting. Going to double check amplifiers etc are all shutting down as expected as well.

[Okedokey]

Sounds like an intermittent wiring issue to me. Check all grounds and connections are solid particularly at the alternator and battery.

[naiku]

Alternator and battery all look and feel fine. Any idea where the engine to frame ground is located? Can't find anything searching except results for a B6.

[80sGuy]

Battery light = alternator.
When a battery is low, you get a weak crank when trying to start your car. Battery light means the charging system isn't regulating currently, therefore from my past experiences I can pretty much assure you that this is an alternator issue. Get it replace before it destroys your battery, but I'd replaced both if t's old enough.

[Okedokey]

Battery light = alternator.
When a battery is low, you get a weak crank when trying to start your car. Battery light means the charging system isn't regulating currently, therefore from my past experiences I can pretty much assure you that this is an alternator issue. Get it replace before it destroys your battery, but I'd replaced both if t's old enough.

He has checked the voltages and they're fine. The light only comes on due to mechanical forces (ie moving and turning) which indicates a wiring issue IMHO.

[80sGuy]

He has checked the voltages and they're fine. The light only comes on due to mechanical forces (ie moving and turning) which indicates a wiring issue IMHO.

My other car checked out fine too, swapped battery, then the light came back on and the alternator went kaput. If his battery is fine and keeps getting the light then it is obviously the charging system.

[Okedokey]

The charging system has been checked under load and reads fine. Not sure why that would be an issue.