SL/R232: Starter Battery Critical Messages
Member
Joined: Feb 2025
Posts: 135
Likes: 47
I think that’s kind of weird too. My CTEK came with my car, and is set up to connect to the main battery in the engine compartment. At the dealership, where I bought it, all the other floor models have their CTEKs hooked up to the main battery also.
I Have been charging my main battery this whole time(1year) and have avoided all the problems that were associated with low battery codes etc.
I have seen special connecters for the trunk accessory battery, but mine is not set up for that.
I Have been charging my main battery this whole time(1year) and have avoided all the problems that were associated with low battery codes etc.
I have seen special connecters for the trunk accessory battery, but mine is not set up for that.
When you refer to the “main battery”, which one is that? The trunk or engine compartment battery?
MBWorld Fanatic!
Joined: Jan 2024
Posts: 2,515
Likes: 900
From: DFW
SL63
The aux battery is in the trunk. It more closely resembles a motorcycle battery, but maybe a bit larger.
Member
Joined: Feb 2025
Posts: 135
Likes: 47
IDK, I’m just trying to learn and figure this car out. It’s so different than anything I’ve owned before.
Newbie
Joined: Jan 2022
Posts: 2
Likes: 1
BMW X5
According to the R232 user manual, the charging terminals are directly under the hood usually used if you need to jump the car. I tried connecting the trickle charger directly to the battery terminals in the back of the trunk but still had battery issues. Once I started charging to the charge terminals under the front hood, all battery issues disappeared. This car has two batteries (one small one inside the cabin and one large one in the trunk) so the proper charging terminal under the hood charges both batteries. Problem solved.
Junior Member
Joined: Jun 2023
Posts: 26
Likes: 12
2022 SL 63; 2017 S-550 Cabrio; 2013 SL-550
I am so glad you posted this. I have been struggling with my 2022 SL 63 over the last two days trying to recharge a dead battery. I left it over night on a fancy battery chargers with all the meters connected over the hood. It showed pull 16amps to charge, so I let it charge all night. By morning it was only 55% charged. It would not start, but at least the dashboard and everything was lighting up. I thought I might work better if I connected directly to the source (battery in trunk). I connected the MB trickle chargers to it and left it all day. By the end of the day, the battery completely dead. I went back to this thread and found your comment about connecting under the hood. I have the CPO and could/should call MB to come fix it, but was hoping to avoid sending in the car and waiting for weeks to get it back.
Hoping its all charged up by morning. If not, will call MB for tow truck.
Hoping its all charged up by morning. If not, will call MB for tow truck.
MBWorld God!
Joined: Dec 2019
Posts: 32,231
Likes: 6,284
I am so glad you posted this. I have been struggling with my 2022 SL 63 over the last two days trying to recharge a dead battery. I left it over night on a fancy battery chargers with all the meters connected over the hood. It showed pull 16amps to charge, so I let it charge all night. By morning it was only 55% charged. It would not start, but at least the dashboard and everything was lighting up. I thought I might work better if I connected directly to the source (battery in trunk). I connected the MB trickle chargers to it and left it all day. By the end of the day, the battery completely dead. I went back to this thread and found your comment about connecting under the hood. I have the CPO and could/should call MB to come fix it, but was hoping to avoid sending in the car and waiting for weeks to get it back.
Hoping its all charged up by morning. If not, will call MB for tow truck.
Hoping its all charged up by morning. If not, will call MB for tow truck.
MBWorld God!
Joined: Dec 2019
Posts: 32,231
Likes: 6,284
