alternator overcharging

Overcharging is usually a faulty voltage regulator on smaller vehicles. Not sure about a big truck.

 

we have had our fair share of troubles with altenators on our ISX as well...............

will be watching this thread

 

Why do you say it's overcharging? Because the gauge moves higher? Are the batteries overheating and swelling?

You really need to put a voltmeter to it and get the battery readings engine off, engine on dry weather, engine on wet weather.

Since it's a wet weather thing, you might have a direct short that's not even related to the batteries or alternator. Take two exposed wires next to each other or a leaking connector, a little water and you have a serious battery drain where the voltage regulator starts putting the juice to her to compensate the robbed voltage.

 

Usually Voltage regulator, but simetimes connections of Voltage regulator to alternator (ground connection usually.

WHat brand is Alternator? Volvo used different alternators with different problems. If it si Mitsubishi it is very difficult to find parts.

 

Wish I would have thought of that....

 

Did you solve this problem

 

Had similar issue 2015 prostar w isx. Intermittent voltage surge to 15+ voltages. Started in desert climate. I thought maybe road salt had dried out inside alt. After became more frequent replaced alternator. V regulator is internal to it. Problem solved. Now 6 mo later V has dropped to 13.3 after brief surge to 13.8 after start. Any ideas? Batteries are AGM type 1 yr. Old.

 

First things first. Clean all your battery connections at batteries, alternator, starter and frame and engine grounds. Prostars have their own cable that feeds the cab. Make sure the main cube fuse at the batteries is clean and the mega fuses at the firewall are clean and tight. Some Prostar systems have a secondary low voltage battery cut out relay mounted in behind the battery box. They are yellow in colour and just love to corrode.

 

I had a same problem, but only after replacing alternator. Twice. Then after a while it settled down. Go figure