Personally, I think the chassis battery is fine. Takes and holds a charge fine. It just went dead sitting 2 weeks in storage. I think Mercedes nature of the beast with all the electronics. It was enough charge to start it but barely. I've had similar experiences with an e350 and c300 I previously owned, and a bmw when they sit for 2 weeks. Heck, my 37 year old jeep does it too.
Personally I know you’re intentionally overlooking an issue you don’t want to deal with apparently.
My suggestion was to get it handled while you may not have to deal with it (financially), although the vehicle warranty is still in tact (you said 2023 model iirc), so I guess you could take it to Mercedes later or just keep masking the problem with a battery maintainer.
I assume by “chassis” battery you mean the starting battery not the house battery.
For the record, it’s not “normal” for any vehicle to discharge rapidly when not operated. Including old jeeps. 50 year old CJ here that I haven’t disconnected the battery cables in years and it rarely gets driven. Sits for months at a time and if I remember or are feeling generous with my electrons I might throw a maintainer on it once in mid winter if I’m walking past it and it looks sad…
Now can’t speak much to German engineering. But can say that a 40 year old VW was an electrical pos 30 years ago. And the one BMW I rented a few years ago had more electrical problems in a week than all of the dozens of other vehicles I’ve owned or driven for 30 years.
Doesn’t mean it “should” be a problem though. I don’t know anyone who pays 6 figures for a vehicle and then accepts it having a fatal flaw like an uncontrollable power draw.
Appreciate the concern, I'll ignore the incorrect assumptions. I'll have them test it at the RV dealership as well as when I take it into Mercedes next month for it's service. Could be a defective battery - or a small draw even with disconnects. I remember when I first got this MH, very cold start one morning and it ran like my old Kubota used to until it warmed up in sub zero temps. And a few times since, when in storage for a few weeks it ran rough for a few minutes even in warm temps. Considered it more of a diesel problem than a battery problem. Frankly I don't really care for the Sprinter Chassis. It rides nice, but it's a little anemic on power when towing and does some weird electrical stuff periodically - alerts for no reason while driving etc. .
I would just pull the battery, charge it and then take it and get it load tested. fast easy and lets you know right away if it is the battery or not. if the battery is fine then you can then look for a drain. no it should not go dead in two weeks, we all my vehicles have sat for at least 2 months at some point during the winter and not one has had an issue starting, and we have real winters 😉
seriously though a pep boys or what ever I think you guys have down ther should do load tests for free, if you were closer I have a load tester and would do it for ya, but I'm not so that doesnt work.
Agreed. I think you and Grit have a good point that there is more draw than supposed to even with the disconnect.
I will have the dealership check it when I take it next week. The challenge with the MBS chassis is that the battery is under the floor pan between the front seats. Requires removing the floor covering, then removing a panel etc. Not impossible, but a huge PITA. I swear German cars make things way more complicated than they need to be. It's been starting fine when I have it here at the house as we prep for a trip and if it does get low, a 15 min drive brings it back and it's fine. It's just the sitting for more than 2 weeks that seems to draw it down. So I think the battery is fine, it's some parasitic draw in storage. I may end up installing my own disconnect switch on the chassis battery so I can ensure nothing draws on it.
That’s not a battery problem. Really Cold and diesel = potential hard starts and running lumpy until the cylinders heat up enough to have complete combustion.
If it operated the cold start stuff (grid heater or glow plugs) and also had enough juice to spin a frozen diesel, the battery is just fine.
Also not a likely cause of running rough when warm. Especially a diesel since they draw very little power to keep the engine running vs a spark ignition engine.
I hope my “incorrect” assumptions helped you since you made no mention of diagnosing the likelihood of a parasitic power draw on the chassis side until it was mentioned.
That wasn't really the assumption I was referring to. But yes, thanks for the tip. I guess even a gritty dog needs a pat on the head now and again. 😄
