Alternator Overcharge

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Giltos

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Hi Everyone,

Has anyone come across an alternator overcharging issue before?

2007 D40 Outlaw. Old alternator died, replaced with one from Ebay, worked fine for 3 weeks, then battery light came on, multi-meter shows 15.5V.

Notified the Ebay store, great customer service, sent me a new one straight away, arrived today. Put it in and same issue 15.5V.

Is it an issue with something in my car or just unlucky and got two bad alternators?

Any ideas appreciated!

Thanks
 
The voltage regulator is incorporated into the alternator. If it's not working properly, I'd check ALL of the electrical connections on the alternator, remove and clean battery terminal connectors (and the battery too). There should be 5 electrical connections (not all in separate connectors). I'd take all of those apart and ensure they were very clean as well.

If that doesn't improve things and the voltage remains high, borrow a battery and see how the new one goes just in case yours has a cell doing something odd.
 
Thanks Tony. Not great at auto electrics but will try my way through!

Have progressed a little. I put my old alternator back in. It hadn't totally died before I took it out. went for a quick drive. Once it spun up and started charging, 15.5V as well, so its not the new alt's I bought of Ebay(Trump), its something in my car.

Battery seems ok, 12.5V standing, car hasn't been driven for 10 days due to this prob.

Bit more background, when i put in first alt, worked fine for 3-4 weeks, ABS light was on. Monday night i started diagnosing that, checking cabin fuse box, IPDM fuse box, pulled fuses checked them, reseeded them etc. Eventually found abs plug near left wheel had come loose, the clip is not great. Replugged, drove ABS light went out, thats when battery light came on and stayed on. So I've created the problem, just not sure where!

Will keep looking.

Thanks
 
Thanks Jonney, tried that too!
I've diagnosed (I think) to wiring loom. Found nissan manuals to diagnose overcharge and it points to the two wire alternator connector, following their steps. There next advcie is repair wiring loom lol.
Trouble is it merges into one massive loom then hard to find where it goes off to.
 
I'd double check the fuses you removed and replaced just in case one isn't seated properly. If that and finding the fault with the abs sensor was all you did, it has to be something simple.
 
All fixed.
The solution, not totally sure!
Had traced wring loom back to cluster switch in fuse box. Tested and both wires all ok.
Cleaned earths, the earth to chassis and motor near battery were fine. The earth near alternator looked fine as well, maybe little dusty, gave it a clean with a wire brush.
Put my old alternator in, to try and remove issue of bad alternator from Ebay.
Started and battery light still on, alternator putting out 15.5V.
Suspected my main battery, didn't have a full spare to swap in, just an old one, uncharged for a year and not enough charge to start in its own right.
Tried joining it in using jumper leads while i cranked and quickly took my main -ve lead off. Let car run off the old battery once it was started. Battery light went out and charge was back to normal 14.5V.
Turned off car, Reintroduced my main battery and still normal.
Stopped/Started many times and all good.
Took for a drive still good.
Swapped back in the new alternator (Trump) I bought off Ebay and still all good.
Test drove and still fine. Loaded with lights, A/C etc.
Hate not knowing exactly how I fixed it, or even if it fixed it at all! Working fine at the moment and will update during the week.

Thanks all for your input!
 
Thanks Bods & Tony, yup had checked fuses. Pulled them all out and re-introduced one a time.
Then found Nissan manual, and followed alternator troubleshooting section which pointed to a wiring loom issue.
 
Maybe not physically, but electrically speaking fuses are part of the wiring loom, and unfortunately the contact surfaces can corrode or get dirt in them and become a problem.

Glad that it's sorted, but if the only thing you did after putting the really old battery in was restoring the current battery, then surely it has to be one of those electrical connections.

Have a look at the positive terminal. There are several connections to the one terminal. Check the ones below the top - the connector that attaches to the battery terminal comes out a little with the primary fusible link visible, then drops down the side of the battery with 3 more connections to it. What if one of those has some corrosion on it?
 

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