Charging issue. Need advice

[Dieselpusher]

I've got a 1992 rockwood regent series with the 5.9 cummins. I've replaced all 3 batteries, alternator, and checked all connections. Digital gauge and factory dash gauge still indicates that it's charging 16-16.5 volts. Any help would be appreciated.

[Dwayne & Shara]

take a ohm meter start the engine and test what the batt. reads then shut it off and test again and see if it goes up or down from what the gauges say. if it is really charging at 16 volts replace the voltage reg. now that to check the engine charging system not if you plugged in to shore power

[Dieselpusher]

I've checked with a meter. It reads the same as my digital gauge. As far as the voltage regulator I'm thinking it's built in the alternator. I'm not aware of an external regulator.

[Dwayne & Shara]

the next step would be take the alt. off and bring it to autozone they will test it for free. if the regulator is in the alt. and charging 16 volts then the alt. is bad some times new ones are bad. they can also tell you if your alt. has a regulator. that is the only thing that will let it over charge,
hope this helps.

[Dieselpusher]

Thanks. I've replaced it with a new one because the old one done the same thing. I guess it's possible the new one is bad too.

[Dieselpusher]

Also I had my old one tested and it was 14.4 at advance auto but it also did 16v on the coach.

[Dwayne & Shara]

that don't make cents

[EDALLSAILS]

I had a Alt replaced three times because of over charging. OOPS, wasn't the alt problem. seems the battery (2 of them) was BAD. didn't make a lick of sense to me but Battery company reimbursed me for ALL 3 alt and labor plus gave me 2 new batteries. Suggest you check batteries and see if they are asking for further charge. I don't know exactly what test they performed to come to that conclusion but they paid thru the nose for alternators, labor and batteries. safe travels... ed

[94-Newmar]

Dieselpusher, You'll need to start going thru a process of elimination. As mentioned by EDALLSAILS above, there are some rare instances where batteries can cause weird issues like you're seeing. So, start it up then disconnect the Chassis/Starting batteries while it's running. Check voltage with your meter at the leads you've disconnected...

If it's still overcharging, hook the batteries back up. I'll assume this is a 3 wire alternator setup. While running pay attention to terminal #2 - this is the voltage sense wire. Remove that wire. Measure the voltage on that wire connected and disconnected. Measure the voltage on the post with the wire disconnected. Do the same with terminal #1 wire and post. What voltages are you seeing on each?

If memory serves me correctly your charging system is controlled by the engine PCM and there is no other "external" regulator.

[Dieselpusher]

94-newmar, I've checked the 2 wire plug on the alternator. One wire has 14.3 v and the other has 16v. All connections at batteries read 16v.

[Dieselpusher]

The bigger red wire has 14.3 and the smaller white one has 16v

[Dieselpusher]

The bigger red wire has 14.3v and the smaller white one has 16v

[Dieselpusher]

Fixed it guys. Someone had the 2 alternator wires crossed. I switches em and now getting 13.8-14.3v at all connections. Thanks for the replies.

[94-Newmar]

That's where I was headed with the troubleshooting tips above. Glad you got it fixed.