LexBrett2

Hi All;
In the process of chasing down causes of a my bad idle, today I noticed that when I turned on my heat my voltage went crazy.

My car battery is new. From my research, it looks like I may have dying alternator? My car starts fine and seems to charge.

Before I spend all weekend ripping the alternator out of my car, and bringing to Advance Auto to test, anyone have any tips?

Thank you very much in advance.

evannguyen

You can test your alternator with a multimeter. Turn your car on and take a voltage reading from the battery terminals. A good alternator should be pushing around 14V or so, at least 13.5V. Now turn all the accessories on (radio, A/C, etc.) and see if the voltage changes.

LexBrett2

I have a glowshift gauge on my dash for the battery; when I turn on heat voltage goes crazy as low as 12v, lights flicker, idle changes. Going to advance auto to get tested today. Does that sound like alternator going bad? There is definetly a correlation between crazy voltage fluctuations and when turn on devices!

evannguyen

Yeah I think it's bad. I would remove the voltage regulator and see if that needs to be replaced first. It's cheaper than to replace the whole thing, but that's just me. A lot of people prefer to replace the whole alternator.

LexBrett2

Thanks for responding my friend. I will let you know how it goes today when I have alternator checked.

LexBrett2

had alternator checked at advance auto 12.8 under load and 14.1 not under load, they said battery and alternator fine thoughts ,?

evannguyen

The only other thing I could think of is loose terminal connections.

miike

There is probably a bad wire in the heater circuits or a bad computer.

Lgraz5

Are you using an OEM recommended battery or one that is "just as good" or "better than original"? Deviating from OEM specs can cause quirky malfunctions.