Battery warning light came on the other day and stayed on for about a minute and then went out. Checked battery with voltmeter and it showed a little more than 12 volts with engine off. With engine on and no accessories on it showed almost 13.6 volts. With lights and fan on it showed about 13 to 13.2. This would seem to be ok or am I wrong?
That's funny. I just checked mine. Same reading. I checked the FSM and it said that the voltage should be between 14.1 to 14.7 V. Conclusion? Our Alternators are slowly dying. It can still charge the battery because it is pushing above 12 volts.
How many miles do you have on your Sentra? My 98 has 160K miles.
From what I've learned on the net, the part that goes bad in an alternator is the voltage regulator. If you are pretty adept at taking things apart you can do it yourself. The manual even shows you how. It is a bit of work, though. I have a refurbished Nissan ALT from my previous sentra that I'm waiting to put in once this one finally dies.
I'm not playing around because I don't have the time to;
1: Install an ALT. It's a bit of labor. 2: Rebuilding an ALT. It's also a bit of labor.If you can do 1 and 2, then you can easily save hundreds of dollars on your ALT replacement.
CD
Thanks for the reply. '97 Sentra has 78,000 miles. My 1983 Bronco has been giving the same reading for years with the original alt. Talk about things "dying a slow death" as you indicated. In 1992 I pulled my trailer out west with that Bronco. The ps pump started to make some really ugly noises and would occasionally stall the truck if I turned the wheel all the way. A mechanic in Hill City South Dakota gave me a price to replace the pump and added that I could come back here in 10 years with that same pump. So I did not replace it. Here it is 15 years later and the same pump is in there and I never experienced that problem again.
Mechanic I know says that reading of 13 volts or above under load is fine.
The voltages you're getting are pretty much normal. If the light is staying on for a bit while the engine is cold, I'd check all the connections between the battery and the alternator. One connection may be getting a bit corroded. When dead cold it won't conduct, when it warms up just a bit or a trickle of current starts flowing through it, the conductivity improves. I wouldn't suspect the alternator at only 78000 miles. Otherwise, just keep watching the light. Once it always stays on, it should be easier to track down. Good luck. Al
I am sticking my neck out a little, but I think the problem could be the alternator brushes nearing the end of life. I'd guess that in the next few months the "batt warning lite" would come and go a few more times, and then always on, followed by a dead battery. Several years ago I had a Corolla with this symptom, and I was able to get a replacement brush set from the dealer and got it installed. It worked for many more years without a problem.
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