Topic: Winter storage charging of the chassis battery (Read 3522 times) previous topic - next topic

I recently purchased a Unity RTB and was wondering what's the best way to charge the chassis battery for winter storage. I have the coach plugged into shore power and the main switch turned off. I read that turning off the main switch also disconnects both chassis and coach batteries and to trickle charge both once a month. I believe, if I have the coach plugged in and main switch off the inverter is charging the house batteries? And with the coach plugged in, the inverter charges the house batteries but not the chassis battery. So what's the best way to trickle charge the chassis battery? I can hook up a trickle charger to the chassis battery, but where to plug it in? With the main switch off I believe the outlets are off? Also is it best to disconnect the negative terminal of the chassis battery or is it disconnected when the main switch is off?

My first thought is if the coach is plugged into shore power during storage, I'm guessing that a non inverted outlet would be available to plug in a trickle charger if the disconnect switch is open. I'm not familiar with your coach wiring but if that is not the case, would it make sense to keep the disconnect switch closed and let the coach systems do their thing and just plug a trickle charger in where convenient?

Turning off the main disconnect turns off the fridge which is preferred to keeping the fridge running all winter. I am not aware of any non-inverted plugs. I am new to the rig. Mine is a 2019 Unity RTB. I am wondering what others do to keep the chassis battery is tip top shape for storage.

If you're plugged in to shore power there should be live 120v outlets available inside the coach, as well as the outside plug. I've got the same setup with my Wonder and will use a NOCO battery tender on the chassis batteries (AGM) once the snow and sun angle get to the point where it's needed. Currently I've got a solar trickle charger on the chassis and the 400w solar on the roof is keeping the coach batteries fully charged.

The shut off switch only controls the 12v power draws IIRC. As to the fridge, it can be turned off independent of the dis-connect switch.

Thank you for the information. Do we need to disconnect the ground on the chassis battery while we trickle charge or does turning off the main switch disconnect the battery?

Our Unity was unplugged and house disconnect was in the off position. We hadn’t been to the storage in a month and a half and everything was dead, chassis and house batteries. We have since plugged into shore power but, per owners manual, left disconnect in the off position. This too should result in the chassis battery running down. We do have a 120v outlet available as well. Should we put a trickle charger on the chassis battery?

Unless Robert has some other charger installed that charges the chassis battery when the house side is being charged (like AMP-L-Start AMP-L-START Starting Battery Charger/Maintainer - Overview Page), the inverter charger won't help. So yes, a trickle charger - more accurately a Maintainer would be necessary. Or disconnect the chassis ground in the driver's footwell (see Sprinter manual for correct procedure).

I have left my unit pugged in all the time summer and winter without a problem but I put a  Xantrex 82-0123-01 Echo Charge for 12 and 24V System using the bottom spare plugin (12 volt ) on the fuse strip under the driver's passenger seat, the nearby ground wire and the 12 volt wire that runs under the outside of the driver's seat to the starting batteries  under the seat (Ford  2020). You only have to run that one wire and all is done) It has worked well for the last 3 years

The year makes a difference on the chassis battery.
I have a 2016 so all I do is disconnect the cable near the gas pedal - no trickle charge or solar with temps as low as -15C; 4 months later on a 6 yrs old original battery it started .  in the MB manual it is called Battery Isolating Switch
for a new model there is fuse #32 that controls the aux battery under the seat that also needs to be disconnected. 
My FLA coach batteries are connected to flex solar panels.  The 12V switch is OFF.