I had a 06 come in with both batts gassing, volt meter ready 11v. Put a tester on the batts at idle they were charging at 15.2v and 70 amps, no load
and an 85 degree day. I could full field the alt via the PCM routines and boost full output to a max of 17v @106amp for only a moment. First thing I did was defect the batts, inspect all cabeling, no change. Reflashed the PCM with the latest version from Dodge that had a patch for low volt meter issues combined with a check guages light. No further low volt reading or guage light but still had way to MUCH charge being pumped into the batts. Droped the signal from the PCM to the ALT and of course the over charging stopped. Installed a used PCM, reflashed it and all is back to normal. Just always be aware of secret key programing post reflash of cummins PCMs with (WCM) wireless control modules

 

Thanks for everyone's input I believe it is fixed so far (knock on wood). Installed the driver's side Optima yellow and so far no boiling and voltage about 14.5V after running for 20 minutes. I will keep an eye out on it and report any changes.

Since the Optima yellow that I installed are D34/75 and not group 65 will there be any issues with this change? The yellow Optimas are rated @ CA 870 and CCA 750 which is about identical with the OEM group 65. What about the temp sensor under the tray?

 

Sounds good, that's why they always say not to replace just one battery when you replace one, replace them both. Keeps from overcharging the passenger batt.