Hey,

I get a spike in voltage when temp gage reads 225 and fan comes on. I just changed alternator 2 weeks ago, battery is 4 mos old, fan switch is 6 months old.
I have been looking for frayed/loose wires all over the place.
I found a half cooked sparkplu wire and replaced it and I stll get voltage spike.

When I mean spike I mean it stays at 18volts while car is hot.

Everything is normal when car is under 220.

Does any1 have similar Probz?

 

What are you using for voltage measuring? Make sure its a decent quality multimeter, not just your stock gauge.

 

Im lookin at gage and when it starts spikin I run to front of car with my FLUKE Multi tester and it reads 20volts.

I pulled off positive cable from battery(car still runnin), battery is 13.9volts
back of alternator is 23 24 volts

 

Yikes, that can't possibly be good. Is this the problem you had with the previous alternator? If not, take this one back pronto and ask for a new one. If you get the same problem, that I can't answer. Too much voltage is a bit out of my league.

 

yeah take it back, it almost sounds like the regulator is in fielded test mode.

 

So,

Would that happen when the car temp is 220 and higher?

 

ok wait a sec. in re-reading your previous post, you say you had 13.9 accross the battery and 23+ at the positive post of the alt. with the battery disconnected and engine running?

IF so that pretty well explains itself. The voltage regulator thinks the battery is flat dead and tyring to charge it since you opened the circuit. However, I would still think 23 volts is quite high. So that may still explain the problem and the alt. is overcharging when called upon. I say this because I know on mine there is a raise in voltage when the fan kicks to probably about 14.5 volts on the dash meter, that would be concidered normal for the load.

Other than that I would look around for some crumby corroded connections on the fan side. But that would normally cause a blown fuse if amperage were trying to overcome a high resistance in the circuit.

 

14-15v is normal for a running car.

 

Thats a good way to damage an alternator.

 

Thanks everyone.


Change Alter, tested OK