SL/R232: SL63 Dead battery issue
I don't find this regimen a significant hassle and absolutely love my SL

While ridiculous that it happens after using the trickle charger, and going for a long drive, the reason I brought it into the dealership 2 weeks ago was new behavior that started to appear. It seems as though the low battery warning started to shut down other systems in the car. My door handles would no longer greet me in the morning, the driver's seat would move about an inch and not fully move to the memory position, the finger print scanner started to behave strangely. And worst of all the pops and crackles disappeared.
During the past two weeks, the dealership took care of two open recalls (the wiring harness, and the rear spoiler). They found a stored fault for the finger print scanner and fixed it. There were some software updates that were installed. The updates apparently restored the pops and crackles and other features that weren't working. However,, the dealership was not satisfied that they got to the cause of the low battery warning. They kept the car for a few more days, put it on the trickle charger and found an error code. They documented everything and sent it to MBNA to ask to replace the battery or some other steps. Yesterday, I received a call from my service advisor. MBNA provided the dealership with some additional software updates for a number of systems which were supposed to address parasitic leaks. MBUSA instructed the dealer to put the car through several drive and sleep cycles over several days. I will probably find out on Tuesday if the car was "fixed".
As I mentioned, my battery has never died. The problems were aggravated with the trickle charger. I could live with most of the annoyances (door handles, seat movement, etc.), but when the pops and crackles disappeared that had to be fixed. In the meantime, I have an E450 Coupe loaner. I can't wait to get back into the SL.
Would you post your service documents once you get the car back? It would be very helpful especially if they have figured out how to address the parasitic loss.
The manual was of course in the glove box--Had the mechanical key but didn't know where to put it. Thankfully because it was outside hours of the dealer I found the SL's digital manual thanx to Google (and Mercedes for having it there)
I was able to get access to the mechanical lock UNDER the drivers door handle (read your manual) but my small lithium booster battery was in the trunk which of course wouldn't open.--I now store it under the passenger seat with elastic cord.
I read in the manual that even when the car is locked there is battery drain as it searches for a signal from Mercedes Me or Smart key. Manual says you can deactivate the Smart key by pushing the lock button on the Smart key twice in rapid succession. That saves battery life on the key but does it do the same for the car battery??
Waiting to hear.--BTW there is no access to power for a trickle charger.at the condo .Key question is how to stop the battery drain in the car when shut and locked. Pleased to find out
Thnx
JP
On a side note the manual says to deactivate your Smart key from accidental use when going thro a car wash! Pays to read the manual.[
Two possible things come to mind. One disconnect your battery for extended down times. Not a great choice as car will have to reboot everything and may lose some things. Two. Put a high capacity deep cycle marine battery with small trickle charge type clips in an insulated box under the hood. Ontario winters will not be kind to an exposed battery. What do others think?
The Best of Mercedes & AMG
Would you post your service documents once you get the car back? It would be very helpful especially if they have figured out how to address the parasitic loss.
Last edited by wem; Feb 6, 2024 at 06:15 AM.
Mine is in the dealer shop again for 4th time & I had same battery low warning issues even after they changed battery and also done all 5 recall.
Mine symptoms; My SL63 always connected to battery trickle charger while it's in the garage, took out for good 30 to 40 minutes driving on highway, put back into garage , turn engine off and then battery low warning comes up on each of last 4 occasion.
Only difference that I've been doing to maintain battery with trickle charger was that I've been connecting negative terminal behind BMS sensor like this in this YouTube video which is recommended method by Mercedes (To Negative & Positive jump post in engine compartment and they are same with this connecting point behind BMS sensor) Video is here & although this is for Ford BMS system, I think it's reflecting general modern vehicles
And I must ask you, Did it finally fixed your battery issue? if so, was it 4 or 5 additional software updates?
Mine is in the dealer shop again for 4th time & I had same battery low warning issues even after they changed battery and also done all 5 recall.
Mine symptoms; My SL63 always connected to battery trickle charger while it's in the garage, took out for good 30 to 40 minutes driving on highway, put back into garage , turn engine off and then battery low warning comes up on each of last 4 occasion.
Only difference that I've been doing to maintain battery with trickle charger was that I've been connecting negative terminal behind BMS sensor like this in this YouTube video which is recommended method by Mercedes (To Negative & Positive jump post in engine compartment and they are same with this connecting point behind BMS sensor) Video is here & although this is for Ford BMS system, I think it's reflecting general modern vehicles
https://youtu.be/I_KmO-KaR4A
And I must ask you, Did it finally fixed your battery issue? if so, was it 4 or 5 additional software updates?
Great news. We had a meeting with one of the Mercedes-Benz factory engineers on Friday. He is very experienced (20+ years with MBZ). I discussed your specific case with him. He ran your VIN and there are 8 new updates/patches related to or designed to solve your issue(s). I should have enough details in the next few days to perform the updates? Can I pick the SL up maybe on Tuesday or Wednesday next week?

Mine is in the dealer shop again for 4th time & I had same battery low warning issues even after they changed battery and also done all 5 recall.
Mine symptoms; My SL63 always connected to battery trickle charger while it's in the garage, took out for good 30 to 40 minutes driving on highway, put back into garage , turn engine off and then battery low warning comes up on each of last 4 occasion.
Only difference that I've been doing to maintain battery with trickle charger was that I've been connecting negative terminal behind BMS sensor like this in this YouTube video which is recommended method by Mercedes (To Negative & Positive jump post in engine compartment and they are same with this connecting point behind BMS sensor) Video is here & although this is for Ford BMS system, I think it's reflecting general modern vehicles
https://youtu.be/I_KmO-KaR4A
And I must ask you, Did it finally fixed your battery issue? if so, was it 4 or 5 additional software updates?
As far as the low battery warning, unless the accessories are running without the engine on, the times that I received the critical battery message were after I put the car on the trickle charger and took it out for a drive. I have not put the car on the trickle charger since I got it back from the dealership. I have not received any critical battery messages. The only messages I received in the past week were that my doors are unlocked (the car is unlocked in the garage at home). I do not double lock my car, and I have even left the keys in the cupholder overnight (accidentally) without any issues with the battery.
SL55 & SL63 appears behaving differently, when I saw critical battery warning I wasn't able to start at all and may be 4 or 5 of additional software updates may not for SL63 if you still getting critical battery warning after those updates-- something for me to ask dealer mechanic
I'm connecting my trickle charger negative cable after BMS sensor & I don't get low battery warning while battery is connected to trickle charger.
However, keep getting low battery warning after driving more than 30 minutes on mostly highway, even with fully charged brand new battery is real frustration for me to deal with, leading me to think car will stop somewhere when battery drops to critical level.
I guess I'll just have to find out what happens and hoping it does not happen in the middle of highway so I can contact NHTSA for mandatory recall
Last edited by Martinkim; Feb 15, 2024 at 05:50 PM. Reason: addition
I'm wondering, have you report this to NHTSA? for safety sake of others
https://www.nhtsa.gov/report-a-safety-problem#index




Mine is in the dealer shop again for 4th time & I had same battery low warning issues even after they changed battery and also done all 5 recall.
Mine symptoms; My SL63 always connected to battery trickle charger while it's in the garage, took out for good 30 to 40 minutes driving on highway, put back into garage , turn engine off and then battery low warning comes up on each of last 4 occasion.
Only difference that I've been doing to maintain battery with trickle charger was that I've been connecting negative terminal behind BMS sensor like this in this YouTube video which is recommended method by Mercedes (To Negative & Positive jump post in engine compartment and they are same with this connecting point behind BMS sensor) Video is here & although this is for Ford BMS system, I think it's reflecting general modern vehicles
https://youtu.be/I_KmO-KaR4A
And I must ask you, Did it finally fixed your battery issue? if so, was it 4 or 5 additional software updates?
The following day I went back to the dealer and they wired the charging posts from the MB branded trickle charger to the battery terminals. I haven’t had a problem with the electrical system since, and I only plug it in if I anticipate the car won’t be driven for a week, The only time I got a critical warning after that was when I left the car at a shop to have PPF and ceramic coating installed. No problems at all starting it then, just the phone app warning.
YMMV




MB in the past typified superior engineering and reliability. My first SL was a 560 was a gem.......and I still have it. What will it take for MB to return to form? I'd start by firing most of the design heads, engineering heads and certainly senior management. Ask the clients for input starting at the beginning of the design. Encourage engineers to concentrate on reliability and ease of service.......think 560SL.
At least MB beat out Chrysler
MB in the past typified superior engineering and reliability. My first SL was a 560 was a gem.......and I still have it. What will it take for MB to return to form? I'd start by firing most of the design heads, engineering heads and certainly senior management. Ask the clients for input starting at the beginning of the design. Encourage engineers to concentrate on reliability and ease of service.......think 560SL.
At least MB beat out Chrysler




