My 2017 Thor Citation Sprinter did not charge the chassis battery when on shore power. There is a chassis battery disconnect on Sprinters right above the accelerator pedal. I found that current drains on the chassis battery include, the remote keyless entry, the dome lights and possibly the ECM as they say to wait 10 minutes after engine shutoff before pulling the disconnect.
I learned the hard way. Three months after not pulling the disconnect, the chassis battery was almost completely drained.
The dome light would barely come on and when I tried to start the engine (diesel), there wasn't enough power to turn over the diesel. Finally had to buy a Schumacher XP750C booster to get it started. All this the night before leaving on a trip.
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