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Voltage Regulator or Battery Problem?


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Hi,

 

 

Has anyone had this happen or have suggestions?

 

I was driving home about 2 miles from the house, and all of a sudden the following happened

  • ABS light came on solid
  • Both the brake light and battery light started fluttering on and off rapidly
  • The A/C blower spun down for a second and came right back on
  • My radio volume got very low (I assume the amp shut down)
  • I finally thought to look down at my ScanGauge and the voltage was fluctuating from 18.3-19 volts

After about a mile, it went back to 13.7 volts and all the other symptoms above stopped except the radio amp didn't come back on, for the rest of the drive home.

 

I popped the hood and found the battery had been outgassing acid from the vents.

 

I was leaving town in another car, so I wasn't able to do any further investigation. When I get home again, should I put the battery on a tester, or just assume I need to replace the alternator or have it rebuilt? I figure it is the voltage regulator. But I thought it was weird that the voltage went back to normal. So once I saw the battery I wondered if it had an internal short.

 

I'd replace the alternator myself, but my truck has an oil leak and I'm not sure I want to deal with the mess.

 

 

Thanks.

 

 

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I just finished with a similar problem. The same lights came on my dash board and following the FSM troubleshooting guide it came down to pulling the alternator and having it tested, which showed it had gone bad. No acid leak from my battery though, although interestingly enough, I just switched to a red top Optima. How recently did you install the Optima?

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The acid venting is a sign of overcharging, which makes sense because you were at 19 volts.

 

More than likely, the reason it went back to normal voltage for the last mile is because the alternator died so you were running off of just the battery.

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I just finished with a similar problem. The same lights came on my dash board and following the FSM troubleshooting guide it came down to pulling the alternator and having it tested, which showed it had gone bad. No acid leak from my battery though, although interestingly enough, I just switched to a red top Optima. How recently did you install the Optima?

That Optima is only a year old. It had a Bosch AGM for 2 years that went bad, but not due to overcharging I ever saw. It had another Optima before that which made it a total of 10 years in 2 cars.

 

I was suspicious that the alternator had completely died for the last mile.

 

I wonder how many years of life it took off my Optima.

 

Sent from my FRD-L04 using Tapatalk

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I've decided to get a junkyard alternator to swap in, so it will be ready to drive Wednesday. And I'll send my bad one to a rebuild shop so I can replace it when the junkyard alternator dies.

 

Does anyone know where the part numbers are on the Nissan/Hitachi alternator to verify I am getting a good original equipment alternator, and not a crappy rebuild or Chinese one?

 

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  • 2 weeks later...

Interesting development. Although my problem hasn't recurred since the junkyard alternator was put in, a local alternator shop says my old alternator tests fine.

 

He is going to go ahead and open it up and check the brushes. But he says worn brushes shouldn't have caused a voltage spike. So I guess it's either an intermittent fault in the voltage regulator that has passed for now, or something completely unrelated to the alternator.

 

Sent from my FRD-L04 using Tapatalk

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The only thing that could cause 19 v and over charge the battery is the alternator, so I would agree with the intermittent fault.

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The alternator guy just called. He said there was a bunch of oily carbon soot in it, and the brushes were worn. He's going to clean it and replace the brushes for $65.

 

That's all worth it. One fancy alternator shop quoted me $175 to rebuild mine. And I looked at how much the regulator was for me to replace. They are running $160 and up! One guy was selling one on ebay for $20. But the picture looks like it is for a different application.

 

Sent from my FRD-L04 using Tapatalk

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I was lucky with my alternator being a Terrano. The stealership didn't have any idea. He sourced a quote for $800 "and that's from Japan and IF they still make them." Was his words. So anyway I found a company in Melbourne on eBay that makes brand new 80a ones for $150 and 5 year warranty. That was 2 years ago and no issues.

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For my info: I thought Optimas were gel pack batteries & didn't Off gas which was why you could even put them in the cab.I've had one Red Top for a decade without issues. I've been running a Yellow Top for about 8 years & have just recently noticed problems with holding a charge. Haven't taken time to definitively determine if it's the battery, the alternator or my quick disconnect which has been coming loose more & more often. In the last year my 5 year old would sometimes turn on the inverter I have wired under the passenger seat & those run downs did the battery no favors. Since I only use the truck periodically I have been keeping the battery alive with an onboard float charger & it's been okay. (Though I occasionally lug around my wife's old battery I keep float charging in garage if I'm running errands I can't count on or afford the time to find someone to jump me.)

 

If I need to replace the battery, any recommendations? When I last converted my vehicles it was about a decade ago & red & yellow tops were essentially the best. I ultimately went with yellow tops as I ran auxiliary lights which could drain the battery down a bit & I found all the fancy electronics on my wife's 09 MDX meant it wouldn't start if you simply left the radio on while cleaning it. I know times have changed & I'm open to suggestions.

 

I'm also going to look at those portable jump packs as I hear they've come a long way in the past decade as well. I'm open to recommendations there too!

 

 

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  • 1 year later...

Hey guys, I put in a new duralast gold battery in my 01 pathfinder two weeks ago. A few nights ago, all lights on the dash came on(same thing that happened last time the alternator went). I kept going and it went back to normal. Stopped at autozone and they said the battery is overcharging. Swapped out the battery and then last night it did it again. A friend said its probably the voltage regulator. #1) where is the voltage regulator? #2) Would it be better to just replace the alternator?

Any advice would be really helpful!

Thanks!!

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The voltage regulator is in the alternator. I found that overcharging can also be caused by old oily brushes in the alternator and the voltage regulator can be fine. If you are really handy you can replace the voltage regulator yourself. But if you need to keep your truck in service, I would pull an alternator at a junkyard, get it tested, and then put it in. You can take your old alternator to a rebuild shop to be properly cleaned and diagnosed.

Sent from my SM-N950U using Tapatalk

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