I noticed a month ago that during the cold weather my battery indicator light was turning on. It would turn off after the car had warmed up (maybe 10 minutes or so). Now the light stays on pretty much no matter what and no matter how long I'm driving. I put a voltometer across the battery terminals while the condition was expressing itself and it read 11.8 volts. I read that it should be reading somewhere between 14 and 15 volts when the car is running. With the car turned off it reads 12.05 votls. I also removed the negative battery cable (with the engine off) and took a reading between the battery's negative terminal post and the disconnected negative battery cable and got a reading of 12 volts. One at a time I removed and replace each fuse in both of the cars fuse boxes until I found out which circuit the short was coming from. It is coming from an 80 amp fuse that is marked "battery." I don't know where to go from here. Could it be the alternator and or voltage regulator? How can I test?
thanks for your help
You have a pretty good handle on the situation, but you need some help. The battery light gets it signal directly from the voltage regulator on the Alternator. The fact that it is turning on and off is indicative of a problem with the alternator and not the battery. However this is what I would do. First I would get me a little jumper test lead and hook it to the output lead of the Alternator, and check voltage between the Positive battery terminal and Alternator output lead with the engine running at high idle ( 1200rpm). This reading should be less than 0.5 Volts, any higher and you have a wiring problem in your charging circuit. Then take the a resding between the Alternator and Negitive battery post. This should be 13.5 to 14.8, if not you have a bad voltage regulator and you need a new alternator. If all this checks out then check voltage between the Alternator housing and the Negitive battery post, again the reading should be less than 0.5 volts. If higher check all your ground connections between alternator and engine and engine to ground. But since you aren't complaninig about hard starting I would guess this isn't the problem. I'm hearing Alternator. Your local autoparts store can do a load check to conferm this. Good Luck, and don't forget to vote
ITS definitely the alternator if the voltage with vehicle running is less than 14Volts+ therefore the alternator is NOT charging enough, that why the battery LIGHT came ON. Replace alternator and that will solve your problem. Sometimes when alternator goes BAd they will actually have a drain on the battery. Good Luck and Thanks for using FIX YA
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