Mercedes Chassis Power Drain

[Moose356]

We also had the same issue with our 2022 Isata 3, that we pick up at the end of September. Coach and house batteries completely drained after unit was in the storage yard after 4days. All batteries fully charged prior to parking, we had just pick it up from the dealer after a few minor corrections to the body. Refrigerator was off, LP was off , house switch was still on. ALL batteries dead called MB roadside assistance they came out jumped a fresh battery to the coach started right up, then drove around for a couple of hours all batteries fully charged again.
Three days later same thing Dead Batteries, took it to the Dynamax dealer looked for any leaks on the coach side, nothing. Then took to MB dealer same tests for the Coach batteries and again no leaks. Getting ready for our trip we notice the Winegard connect 360 flashing green! We turned that off at the entry and have not had any further issues!
Any ideas? I called Winegard and they said it was impossible for their unit to drain the batteries as it does not draw enough, but our batteries are still charged. Also why would the house batteries cause the chassis batteries to discharge? I thought the Li BIM was supposed to prevent that.
Sorry, for the long response as I am still trying to puzzle this issue out.
Brian any thoughts?

[bclemens]

None.... I do have engineering looking into the Li-Bim, but so far we have found nothing.

I do agree, there is no way the WInegard "should" draw down 200 amp hours of lithium,
BUT that Winegard is not only an antenna, but also a router. I will add this to engineerings data and maybe we will run some tests on that specifically.

[Chuck_S]

drove around for a couple of hours all batteries fully charged again.
Three days later same thing Dead Batteries

No surprise. All ya got driving around was a small surface charge; the batteries were NOT charged nor could they be from the engine alternator in that little time. Battery chemistry isn't magic and if you have lithium house batteries their higher voltage will always try to charge the starting battery if they're connected together.

You may want to forget the exotic charging system and just isolate the house and starting battery with a manual switch as is common on motorboats. Neither elegant nor automatic but works. Off-1(engine)-Both-2(house). Off in storage. Both when the engine is running and charging both batteries. 2 (only) to protect the starting battery.

-- Chuck

[Moose356]

I agree drive would only partially charge the batteries. Here the charge levels this past week with the winegard off. Chassis 12.8 house 14.1v then chassis 13.8 house 13.9 then both at 13.4, then both at 13.3 for a couple of days then we drove it for a day and both ended at 13.6.
I thought the BLM was supposed to prevent identical charges between the batteries, I don’t really know how that works. I also thought maybe the battery switch on the dash was sticking so I pushed that and you could hear it click on and off so I believe that is working correctly.

[Moose356]

Just had a thought that "maybe" the iRV36 Technologies might be the problem. If you don't hit the mute button long enough to turn it off, you are just muting the unit and it is still drawing 10A. If you don't use the battery disconnect when you store the unit, for a week or so, then the radio draw would be continuous. I know when I have hit the mute button thinking I turned it off but find out later it is still on just muted. When we had MB jump our unit we alway had disconnected the house batteries, which shut down the radio. So when I had the unit at both dealers they checked for battery leaks and found nothing as the radio was not muted/on.
This radio is the only different item from our previous 2021 Isata 3 that we had NO issues with the batteries. So could the radio be the issue? Is the radio wired to the coach battery or the house lithium batteries? Why would the Li Bim not prevent the the drain from the coach battery.
I know I am just throwing "darts" at this because I am not an electrician. But with Winegard only drawing 1a (per Winegard) and the radio 10a (per the manual)?

[Big Dog 1]

So when in storage not connected to shore power and outside do the lithium batteries with solar provide a trickle charge to the chases battery? MB recommends disconnecting the chassis battery near the foot pedal if stored for any length of time but is this really necessary with solar and lithium batteries? Is there a BIM taking care of this? 2022 FW

[Moose356]

When we store our rig outside (we have no inside storage) I first make sure the IRV radio is off not muted. Then I hit the red battery cutoff switch, to turn off everything in the rig, I then touch the Firefly screen to make sure it is off. That’s it when we come back all batteries are fully charged.
We are in PHX for the winter and it sat for 3 months without being touched. When I went to get it ready for a trip I unlocked it started it without issues.
I haven’t tried to recreate the battery issue by leaving the iRV radio on, I don’t want to mess with it because I do t have a spare battery pack. But since I have made sure the radio is off no issues. I have even left the battery disconnect active for weeks and everything still started properly. Our rig has worked perfectly after that discovery.