My battery gauge is jumping around

**cmaross01** · 09-06-2006, 07:24 AM

Its seems that @ idle the the car is fine, when I'm driving the volts will drop under 13 on the gauge and my headlights will dim and my check gauges light will come on. Then it will go up back to normal for a moment and drop back. Is it the alternator? maybe a loose wire somewhere. I changed the battery about 6mo ago. Any suggestions of what it might be would be appreciated

**0rion** · 09-06-2006, 07:45 AM

My money is on the alternator. There's a couple of ways to test it. The easiest is to use a multimeter set on dc volts and check across the battery terminals with the car running. You should see ~14.4 volts with the car running. The other way is to start the car and turn on the headlights and disconnect the battery. If the car dies then your alternator is shot.

**Danger731** · 09-06-2006, 09:28 AM

Originally Posted by 0rion

My money is on the alternator. There's a couple of ways to test it. The easiest is to use a multimeter set on dc volts and check across the battery terminals with the car running. You should see ~14.4 volts with the car running. The other way is to start the car and turn on the headlights and disconnect the battery. If the car dies then your alternator is shot.

That was an old school method but is that safe for newer cars, I heard you can F something up by doing that. ??

**camky99** · 09-06-2006, 09:39 AM

I work on cars for a living, yes you will F somthing up like your ECU for starters. What Danger731 is saying is very true, that is the old school way. The easy way would be take your car to a shop or even a parts house that will check your charging system for you. That is the best way to find out what is going on. just my .02 cents. Good luck

**StangKiller615** · 09-06-2006, 11:38 AM

Defiently sounds as if your alternator is on its way out.

**sunsetorangess** · 09-06-2006, 03:27 PM

If you take your car too say chinazone they will check your chargin system for free. Get a multimeter like said above and see how many volts its holding while running. Check your batt terminals for corrosion and make sure there tight.
Are you saying it runs low or just drops down once and a while? Mine drops when im at idle and the fans first kick on but then raises again.
J

**0rion** · 09-06-2006, 07:58 PM

Originally Posted by camky99

I work on cars for a living, yes you will F somthing up like your ECU for starters. What Danger731 is saying is very true, that is the old school way. The easy way would be take your car to a shop or even a parts house that will check your charging system for you. That is the best way to find out what is going on. just my .02 cents. Good luck

That's the first I've ever heard of that. Not that I'm doubting you guys. I've just never heard of that being a problem before. I normally use a meter to test but have pulled the cable in a pinch many times before without any problems. Guess I'll stop doing that.

**Redphoenix1998** · 09-07-2006, 12:06 AM

you can cause a short and burn up one of the wires as well as fry a board in the ECU. There is a grounding srap in back of the alternator, check for looseness. Check all your grounding wires as well

**SR71** · 09-07-2006, 01:55 AM

Sounds like an alternator to me. Just had to replace mine. This summer has been a lot hotter than recent years, and I'm pretty sure that, along with my sound system probably took mine out. Just get a voltmeter, turn on your call and all the accessories at the same time, and make sure it doesn't drop below 13volts. Depending on the "draw" of everything, it may dip and come back up, which is normal. But...If the volts keep dropping and don't hold, it's the alternator. Mine dipped as low as 11.6 and was still falling when I tested mine. Hope this helps.

**cmaross01** · 09-07-2006, 07:19 AM

My car died today, the volts went down to 8 and continued to decline until it ate sh--. It sounds to me that the alternator isn't doing it's job which is alternate power back to the battery.

Would most of you agree.

**BlackZ28629** · 09-07-2006, 07:37 AM

ALTERNATOR!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Go to Auto Zone IF you just have to check it out; they'll do it for free.
OTherwise, change the alternator out; that is your problem.