One piece of info for those with Cummins L9/ISL engines. These has an inlet grid heater that will pull chassis battery current when the key is first turned to the run position (wait for the yellow coil indicator to go out before cranking), but this grid heat will continue to cycle on and off for 2 minutes after engine start if the ambient temperature is below 65F. After the alternator starts regulating voltage above 13.2 volts, each time the grid heater cycles on, it pulls the voltage down to around 12.5 volts.
On my American Coach Dream, if I try to run the slides with the voltage below 13.2, the slide controllers will lose their programming. Donít know if the Entegra coaches have similar issues with low voltage when the grid heater cycling.
Regarding this thread, if you run the block heater for 30 minutes before starting, the grid heater wonít cycle. The voltage comes up and stays well above the 13.2 volt minimum I need to keep the slide controllers behaving.
Those with the 605 Cummins, never mind. Those engines do not have the inlet grid heater.