Can dead batteries cause a derate?

How can you have dead batteries and be running?

 

I would say yes. Newer vehicles, all of em, are a lot more reliant on solid power than we like to admit. They do all sorts of weird things when voltage gets low.

If you know the batteries are shot anyway I'd start there first.

 

it derated the engine running

 

bigger question i would thk. would be why isnt it doing it driving.

 

Yes.
Replace all of them with new batteries.

Clear code and do a forced regen.

1 single battery can give you problems.

Replace all them.

Don't forget to check for bad,loose or dirty battery cables.

Don't listen to people who don't know newer trucks!

 

Batteries don't do zip with the engine running. The alternator provides 100% of the electricity under normal circumstances. The only purpose of the batteries is for starting, absorbing small voltage spikes from the alternator and to supply power only when electrical system demands exceed the alternator's output.

 

I just had this happen a few weeks ago. Went out to a customer with a derated ISX in a newer Pete for NOX sensor power and DEF line heater f/c. Found 9v at the power distribution panel that supplies power for aftertreatment. 9v on insite. 12v on starter. Followed it back found a shorted plate in a battery which happened to individually run thru an OEM 100a fuse to the Pete panel.

When t/s engine faults, always a good idea to start with clean good 12v. Cummins should have ECM power directly off battery thru a 5 amp fuse. NOT off starter or alt. Now that doesn't always happen from OEM side (especially on industrial. Looking at you, sennebogen!) But thats what its "supposed" to be per cummins. So crappy batteries will absolutely cause headaches, faults, and derates. Just a thought.

 

Crazy enough... Yes.

I've seen dead, weak batteries and alternator issues cause derate and other electrical issues on the new trucks.