Electrical Alternator charging battery too high

[Ayden]

I have replaced the alternator because I had a spare and it is still overcharging the battery when I’m driving. After a little it will correct itself but today it started to do the same thing then when I came to a stop with the car the electric went out. I pushed the car to a safe spot turned the key and there was still charge to where I could put my windows up. Anyone know what could be wrong with it?

 

[AeroCoupe]

Year of car and which alternator i.e. did you upgrade to a 3G or is it a stock Fox alternator?

 

[Ayden]

It’s 1989 GT and I believe a stock alternator

 

[89ripper]

What was the original reason for replacing your alternator?

 

[Mustang5L5]

WHat voltage are you reading? A properly functioning alternator should output 14.4-14.6 volts at a min RPM value. The alt needs a certain speed to make full charge. Any slower (due to U/D pulleys perhaps) and it won't charge enough.

The alternator has a voltage regulator which controls that output. It can be replaced, but there may be a wiring issue with the vehicle causing it to be high if two alternators did this.

You can bring the alt to a auto parts store and have them test the alt voltage regulator.

You'll want to check wire 38 and 36 to see if the fusible links are OK and you have power on these wires.

Wire 904 runs to the cluster to the BATT warning light. Often if folks put LED's in here, it causes charging issues.

 

[General karthief]

What size pulleys are you running?

 

[manicmechanic007]

What voltage are you running?
A sulphated battery will run 16 volts when there is nothing wrong with the charging system
That causes problems
Test it with a DVOM
Agree with having the alternator tested if in doubt