House battery interface

[droadrunner]

I have a 94 B 190 and inadvertently left the ignition on overnight. The chassis battery was dead as a result ( no surprise ) but so was the house battery and that was a surprise! Nothing in the camper was on or running and both batteries were fully charged and are nearly new.
Is it normal for the chassis battery to discharge the house battery? I know the house battery is charged by the alternator, by running the generator, and I believe using shore power.
Needless to say my backup plan to jump start the engine from the house battery was a dismal failure.

[Lily&Me]

Hmmmm, I don't know, exactly, but there may be a drain if the "use" battery switch is left on during an event like this.

I have discharged the chassis battery by leaving a heavy duty, 12volt charger plugged in for a weekend, so don't feel too bad.

I would charge everything up and watch it carefully. Take a drive and then plug in for a few days, with your "use" switch on, before assessing again....just my humble opinion.

B Vans are the way to go.


Maggie

[Protagonist]

Originally Posted by droadrunner

I have a 94 B 190 and inadvertently left the ignition on overnight. The chassis battery was dead as a result (no surprise) but so was the house battery and that was a surprise!

Is it normal for the chassis battery to discharge the house battery? I know the house battery is charged by the alternator, by running the generator, and I believe using shore power.

I don't know if the B190s include a Battery Isolation Module (BIM) but if they do, then the BIM is supposed to prevent this from happening. Its purpose is to connect the house and chassis systems when there is any source of charging power— shore power, generator, or engine alternator— and disconnect the two systems when there is no source of charging power available.

So, once you get the battery situation fixed, I'd say the next step is to investigate the BIM.

[droadrunner]

Thanks for your responses. Batteries have recharged while traveling in MI. The BIM sounds like my next research project. If I don't get it figured out prior to returning home, hopefully Airstrean which is 20 min from where I live can offer some insight.
Thanks again,
Marlin

[droadrunner]

Stopped at Airstream factory this afternoon and resolved my question as to why my house battery was also totally discharged as a result of leaving my ignition on. Answer in my laymen's terms are:
When the ingnition is turned on, a wire running from the ignition switch to the electrical panel is energized opening the circuit to the house battery allowing both to charge when the engine is running. This circuit remains open as long as the ignition is on, in effect connecting both batteries. When no charge is being produced by the alternator, both batteries remain interconnected until the ignition is turned off. Therefore if the ignition switch is on and the chassis battery is discharging with the circuit still open, the house battery will also be discharging.
I committed the only scenario where the house battery is not independent.
Ignition off, circuit broken. Leave headlights on, dead chassis battery, good house battery, etc. Whew, think I may have confused myself😊