engine battery drained by roof vent fan?

[tahoe]

Hi, I left the roof vent on for a day & half and then could not start the engine. No lights in the coach & engine would not crank at all; nothing. Not smart, I know, but does the drain on the coach batteries affect the engine compartment battery as well? I know that the alternator recharges the coach batteries, but will the load on the coach batteries drain the battery in the engine compartment?



Tahoe

[Pip]

It shouldn't. The coach and cab batteries a separated by an isolator to prevent that from happening. Yours may be defective or the terminals are corroded. Clean all the terminals in the battery compartment and while you at it charge the batteries while they are out of the coach.(Don't charge them while connected or you can damage the converter)