You are going to want an isolator on there as well. Otherwise, the batterys tend to discharge each other.

 

No need for an isolator... Im getting 2 new batteries.....

 

Doesn't matter. You still want the isolator.

 

How do you figure? The cummins i pulled the tray out of didnt have one and i took the oem wiring out of the cummins for the 2nd battery as well....

 

On the cummins, the batteries are ran in series.

 

Wrong... The are ran in parallel... Pos. To pos. And the neg's are grounded the yhe block and frame.

I took a peek at the wiring just to be sure before u started pulling wires...

 

The cummins uses a 12 volt starter?

 

Yes sir... All the electronics on the cummin are alot of the same in all the other models as well... All 12 volt my friend.

 

I have 2 batteries for the 454 in my RV (engine and onboard air compressor) and 2 batteries for the "house wiring." Alternator capacity has to be enough to charge both, lor electrical load will OL alt and batteries will draw down.

Check ampacity of the alt on the diesel.

 

Neat. That's news to me. (obviously. ) You can give it a shot, and see what happens. Got nuthin' to lose.