Battery voltage

[09megacabcummins]

I was having issues with my truck overcharging on my 2003 ram 3500 5.9 cummins and i put a new external voltage regulator on and now its charging at 14.2 but the problem that did not get fixed is the battery gauge will just occasionally drop to 0 ( did it before I changed the regulator as well) but it still charges at 14.2 but sometimes the gauge works

 

[McBroom]

Sounds like something in the dash itself.
It would suck if you had to R/R the cluster. Thats a tough one to trace down.

Blue Mule

 

[09megacabcummins]

When I first turn the key on it starts up to 12 volts then within a second or so it drops to 0 is there a sensor somewhere that sensors the voltage or it it built into the gauge cluster

 

[Nick_rp]

After a spat of overcharging it would be a good idea to get the battery and alternator tested individually.

I dont know the specifics of your truck but generally the battery gauge reads battery voltage first and switches over to charge voltage so that 12 your seeing is current battery voltage and 0 is charge until you actually start the engine and than it should raise between 13-14ish. If its falling to zero while the engine is on thats a sign of an issue at the alternator.

 

[09megacabcummins]

I guess I should have mentioned I just put two new batteries and and a new alternator the first alternator was fine and both old batteries were toast so i got two new ones and its constantly charging at 14.2 now reading with my amp meter