batterie light on

dodge sprinter 2500, 2006 , 158''

when i start the van the batterie light come on and turn off when engine turn at 2000 rpm +, and come back on when below.... I charge the batterie at 90% and next
morning the same happen.

i take out the main batterie and it test it OK but weak, the alternator as been change last year.

Can it be the auxiliary batterie under the passanger seat (older then the main one) that cause problem ? i look at the fuse box by the driver seat and dont see any fuse or relay to disconect that batterie from the van and see or dont use it any more.


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UK 2004 T1N 313CDi
You need to measure the battery voltage with the engine running and under the different circumstances you outlined in your OP.

If you don't have a multimeter they only cost a few dollars at most DIY or car spare stores and would be a worthwhile investment.

I am with the others that this is likely a failed alternator irrespective of the fact it was only recently replaced. New parts sometimes fail quicker than you would expect!

check wires and OK and not loose.

alternator at idles is 11.73 volts and at 2000+ RPM the light come off but alternator still at 11.73 volts.

look like my alternator. can it be the regulator inside since i change it 1.5 year ago.



Erratic Member
Turn off your engine and it will still read about 11.73 volts (perhaps even higher, since it won't be draining to run the engine).

On the "grounds" ... carefully inspect the "engine ground strap" which goes across the battery-side rubber engine mount.


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