Prosine 2000 / Batteries

[Marcblou]

Hi,
Place my Airstream landyacht in storage for the winter and was changing for 4 months. I had the disconnect off.
The coach batteries were fully charged but the motor battery was dead. Can someone explain why this happens and/or a solution.

Marc

[moosetags]

First off, welcome to the Forums. We're glad to have you with us.

Is your charging system set up to charge the engine battery along with the RV batteries? If not, the answer is obvious. If the engine battery was charging, the condition of the engine battery may have been poor going in. Did the engine battery take and hold a charge affter you found it depleted.

Brian

[Marcblou]

The motor battery kept it charge after being recharged.

Marc

[overlander63]

It was drained both by parasitic draw, and normal natural discharging.
Parasitic draw is that from the engine computer and other things like the radio memory and clock.
Normal discharge is about 25% of charge over a three month period. Cold weather accelerates the process. To slow down the drain next fall, unhook the negative terminal from the battery. It will still discharge, but not as fast.

[Marcblou]

Hi,
Thank you very much guys. I will disconnect the negative terminal.

Thanks again

Marc