Confusing starting problem

I had the same staring problem with my T2000, had amps but the truck wouldnt turn over. After hours of looking and not having a extra fuse for the relay, I had a mech show me how to bypass it until i could get to a KW Dealer. ran a wire from under the relay (with the key in the on position) then touched the wire to the positive terminal side of the batt. and she fired right up.

 

It appears we have some very intelligent advice out there. Let me give you the perspecctive that I have had to use with the military and it also applies for commercial application. You have what is considered as series/parallel battery system. Though you do not have a series/parellel switch to change fro 12 to 24 volt start you still have the same charging problem as previously described. All four batteries do not get an equal charge all the time. Normally that is the front two batteries that get a full charge. To keep all four batteries in a stable state of charge you can rotate the batteries. The other consideration is for changing all four batteries at one time and it was described briefly above. Used batteries collect sulfate on the plates, when that sulfation build up hits the bottom of the battery case, it will short the battery out thereby causing a no start condition, unless you isolate the bad battery. The other thing is that an alternator will charge to the lowest charged battery and can cause the good batteries to cook off all of the acid and water inside. I go thougth a lot of batteries in the Army due to poor maintenance and see this everyday.

 

i remember back in the days of pulling wrenches school--there is a way that might help when batteries do suphate--of course my memory is bad--but i think you put a load on the batteries to discharge them--then long slow charge with a good charger--i guess it does work sometimes--but then again --who has the time to do it

 

Starter relay fuse. The mech. had me run a wire from under it to the positive terminal with the key in the on position and it fired right up..was able to get to the shop to get a new 1.

 

That was my first guess, and if the battery cable to Cummins motor is bad that might also be preventing the Apu from firing.