Voltmeter dropped off and "Check gauges" light dinged at me on the way to work yesterday. Got out the ol' voltmeter and tested the alternator-- sure enough, not charging. Just curious about which amperage the stock alternator is (napa has several listed) and if the brushes are replaceable in it or not. My Chilton manual says no, but I was suspicious that may just be to cover their hind quarters against people who have no business inside an alternator.As a side note, I was impressed with how little the batteries drained on the drive home! I guess with no ignition system to be running, there isn't a whole lot of load on the batteries other than the PCM (I kept the lights, wipers, stereo, etc. off).

Voltmeter dropped off and "Check gauges" light dinged at me on the way to work yesterday. Got out the ol' voltmeter and tested the alternator-- sure enough, not charging. Just curious about which amperage the stock alternator is (napa has several listed) and if the brushes are replaceable in it or not. My Chilton manual says no, but I was suspicious that may just be to cover their hind quarters against people who have no business inside an alternator. As a side note, I was impressed with how little the batteries drained on the drive home! I guess with no ignition system to be running, there isn't a whole lot of load on the batteries other than the PCM (I kept the lights, wipers, stereo, etc. off).

With a bit of testing with a DVM on Ohm setting you should be able to see if the field brushes are good or something else happened. As for battery drain basically got all the computers on the CCD network (ECM, PCM, ABS, AirBags, Central Timer, etc) Then you got the VP44 power the PSG on top.So if you figure you got about 200 amp hours of batteries (roughly guessin') with a 20 amp load (roughly guessing again) you could drive for ant least 10 hours before consider battery dead at 10.5 Volts but the electronics on a Cummins will continue to run all the way to 8 Volts which will most likely do damage to the batteries for sure.