2018 Pleasure Way Lexor TS/2017 Promaster 3500 Chassis battery Drain Question

[OregonPerson]

Hello,

My 2018 Pleasure Way Lexor TS on 2017 Dodge Promaster 3500 recently had a new OEM AGM chassis battery installed. It is now stored outside at a storage facility with no electrical outlets for shore power plug in available. I planned on driving it for about an hour or so every couple weeks to make sure the AGM battery was topped off, to exercise the automotive parts, move tires, and get fluids up to operating temps.

The "new" chassis OEM AGM battery reads 12.2V with engine off, lights off, doors closed, no radio on, no phone chargers in dash power outlets, after being at 12.8V the previous day, anybody have suggestions why??

I don't have any parasitic loads that others with units like mine have and they seem to be able to go 2-3 weeks safely between driving.

My 180A OEM alternator seems to be charging fine, the AGM chassis battery reads around 14.4-14.5V while driving.

My Pioneer DMH-6600NEX media receiver with 9" color display and XM antennae which replaced the OEM Uconnect media unit with 5" display uses 2.5milliamps when engine is off. I have a Sure Power 1314-200 unidirectional isolator that the AGM chassis battery and the 2x100 Ah Lithium coach batteries are connected to but the Lithium batteries are currently disconnected by a disconnect key to prevent solar or alternator charging due to below freezing temps at night here in Oregon. I have not pulled the ground plug connecting the isolator, didn't think I would need to if not charging. I have 300 watts solar to charge lithium coach batteries but not charging while in storage due to night time below freezing temperatures.

[markopolo]

I'd suggest starting your troubleshooting with the Sure Power unit. Maybe it's not releasing when expected or has some other fault in the electronics. Most basic test would be to check if the Sure Power is warm when the chassis battery is below 12.8V.

Alternately, disconnect the small gauge ground wire on the Sure Power unit when the chassis battery is below 12.8V. If you hear a clunk sound then the Sure Power unit is staying closed longer than it should.

Another test would be to drive for 1/2hr to 1hr to charge the chassis battery then disconnect the small gauge ground wire on the Sure Power unit. Let the van sit overnight and check the chassis battery voltage again to see if it is better than the 12.2V you are currently seeing.

After that there are good tutorials out there on how to track down parasitic draws. Find one & follow the steps.

Some Promaster owners might see this post & offer some suggestions.

[reilym]

You should disconnect the coach batteries entirely from the alternator/chassis battery using the red key under the passenger side rear seat/ottoman when you are done exercising it. That will eliminate any possibility that something in the coach is draining the chassis battery. The Sure Power battery separator is supposed to do that for you, but as was said, I have seen that solenoid stay closed after shutting of the engine.