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Battery light at low RPM

C

CRZYDRVR

CEG'er
Joined
Aug 4, 2000
Messages
263
Location
Bernalillo, NM
Constant battery light below 4500RPM. Above 4500RPM it turns off. Shut car off, restarted and the light went away for a few minutes. Car started several times like normal, so the battery is still strong. My GF mentioned she could smell something "hot" at the time of the light but we were in traffic so who knows what car the smell came from. Checked under the hood, nothing on fire or anything.

I have seen the battery light turn on a few times in the past, but only for a second or 2. It never stayed on this long.

This is the opposite of the usual alternator problem, is the answer still the same? Im at work so I dont have access to my usual tools.
 
yes, do the simple things first.

REMOVE your battery clamps from the battery terminals, CLEAN THEM (even if they look clean) and replace, tightening completely. they may "feel" tight if performing the highly technical wiggle-test, but still be loose.

after that, if the problem remains, inspect the alternator's wiring (the 3 wires going in to the alternator) and make sure the nut isn't backing off making a loose connection, etc, etc.

Lastly, you'd like to (optimally) have a voltage reading at the battery WHILE the problem exists. IS your alternator charging while the light is on? Is your battery voltage 13.2-13.8vdc or so?
 
Bet your alternator is bad! You probably lost some of the regultor diodes. Take a voltage reading at the battery you should see close to 14 volts with the engine running. Take care if it before you get stranded. You are probably running on the battery.
 
Last edited:
ok im having something of the same problem. same issue only thing is it has been over a month and i have had no issues with lights, stereo or starting(other then replacing the battery that went bad) car runs strong only thing is the light is on. i checked voltage too. its 14.45v
 
I was not able to get to a volt meter while the light was on. Im going to check the connections and do some general troubleshooting tomorrow at work. It never lit up while on the drive home today.

Thanks for all the input guys.
 
Ok, checked all connections, and found no problems. Kept getting inconsistant readings with a handheld meter so I installed an Autometer Voltmeter I had laying around. I get a max of about 13.9 volts at any RPM, so needless to say the light is on all the time now after about 1 minute of driving. New alternator is on the way.

I also noticed the A/C compressor will no longer engage. Could this be related to low voltage, or do I have 2 seperate problems? Everything else on the car works so far.
 
The A/C is probably separate problem (leak or clutch), but wait till you fix the alternator and see. The A/C clutch draws a lot of current when it goes on.
 
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