Chassis battery drain

[JDMC-4]

I was camping this past weekend in Florida and the night temps went to 30 degrees. I always turn off the generator at night because of the noise and vibrations. I never had and issue with battery drain in the morning at higher temps but then the furnance was running a little more often than normal. Woke up and All my batteries including the chassis batteries were to low to start the gen or the 6.7 Cummins. So I ran a ext cord from my neighbor and charged the chassis batteries. My question is how do I isolate my chassis batteries so they will not get run down from the furnance again?
2021 Isata 5 30fvw.

[Desert Boat]

They should be automatically disconnected by the BIM (or LI-BIM).

If the chassis is getting drained by the house, there is either something ahoo in the wiring, the cross connect switch is permanently enabled, or there is something wrong with the BIM.

The cross connect switch is typically aux switch #2 - ensure that the setting for that is "momentary" in the Ram commercial settings menu.

This post provides a quick functional test of the BIM properly isolating.

[JDMC-4]

Desert Boat, I went on the Ram commercial setting and yes it was on momentary.

[Desert Boat]

Next steps would be to check the BIM functionality, then to check for a house load that has been inadvertently connected to the chassis.

[JDMC-4]

Is the BIM located by the house battery?

[Desert Boat]

Should be in the electrical bay near battery disconnects, etc. But been a while since I looked at a 30.

For the functional test you don’t have to even look at the BIM, you read the gauges.

[JDMC-4]

I'll check it out! Thanks !