Chassis battery drain question

[Gmthrust]

Does your Wayfarer have a BIM (battery isolation manager)? I just discovered, with help from a previous post by Judge, that our BIM was wired backwards. Found out because we upgraded to lithium, and it required a different BIM. So we just swapped same for same wire and the truck was not charging the batteries. Then I remember Judge’s post and switched the two wires - bam!

[Bob Denman]

BIMS, BIRDS, and all the other Bees: Mercedes doesn't like their chassis battery to be taking a charge from the coach side of things...

[Gebills]

Originally Posted by paulwadley

Hi Glenn

I just sent you a private message with my cell phone number. Just send me a text and I will send you a photo of the battery disconnect on the sprinter chassis motor home. There is a black cable connection with a red top just above the gas pedal. There are instructions on a sticker next to it that explains the process to disconnect the battery.

I just researched it a bit more and that cable listed as a battery master switch is actually the ground cable(negative) from the battery to the chassis.

Paul

Thanks Paul, I ran over to the storage yard day before yesterday and found the little adhesive sign up under the dash, and sure enough, if I weren’t half blind, I probably would’ve seen it. I attempted to pull the connector off but it was giving me a bit of a hard time. So today I’m going back with tools. It came out part of the way after I pushed the red button down but the cable is behind the lower part of the dash plastic moulding where it joins the floor rubber components. That’s sure going to be a lot easier than pulling that floorboard and step-well out every time I want to disconnect the battery. Thanks for the help And thanks to the original OP, Dabobo, for bringing the subject up. Glenn

[Dick1030]

Originally Posted by Bob Denman

BIMS, BIRDS, and all the other Bees: Mercedes doesn't like their chassis battery to be taking a charge from the coach side of things...

MB likes the chassis battery to charge from the engine alternator and not much else. You might get it to charge from the generator but that takes a long time. I messed up and forgot to pull the coach battery disconnect (to the right of the gas pedal) and my coach battery was drained after a few days. I had to go looking for the positive cable that hangs somewhere in the driver's side of the engine compartment to jumpstart the battery.

Next step is a trickle charger with a controller from the house battery to the chassis battery.