Voltage Spike - Both Low and High


Mar 3, 2006
Nutley, NJ
Ill start off by saying that it first happened two days ago when i turned onto my friends street. When going down the street I noticed my red battery light was on and my volt meter was at 18v's. I shut off the car and coasted down the road. When I got to his house I started it back up and everything was ok and the volt meter was reading where it normally does.

So the day after which was yesterday, I brought my battery and alternator to autozone and everything checked out fine.

Tonight when I was bringing my girlfriend home, as I was leaving I saw my lights get brighter and it was at 18v's, then it steadied out and then it went lower in volts to probably around 10 or so. Then it came back up and steadied out.

What does this sound like to you?, I wish it didnt pass at autozone so I could have just gotten a new one. To me it sounds like a voltage regulator or something of that sort. I also do have a spare alternator laying around so i might toss it on but then I still cant get a new one from autozone.

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Active Member
May 21, 2005
South Florida
try the regulator from the spare. i recently had an alternator test good but still did not charge when i brought it home. after double checking everything on my end i knew it had to be something with the alternator. im not sure if they bypass the regulator during the test but i talked them into giving me another and everything has been good since then.


Mar 3, 2006
Nutley, NJ
now that I am thinking about it, when it stops snowing I am just going to toss on my 200 amp alternator and I have an old alternator sitting around that has a bad voltage regulator and Ill take that off and put it on the one that is currently on my car and then ill bring it back and have them replace it.

I checked for loose wires and grounds and couldnt find anything...I had my battery charged to full capacity yesterday. So i know it pretty much isnt those two things.


"How long does it take to get help in here?
SN Certified Technician
Nov 29, 1999
Another regulator vote/guess. It sounds like you've done one, but if you haven't, it takes about 30 seconds to swap them out.
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