SL/R232: Ongoing Battery Issues




Just curious if you have actually experienced a battery related failure, such as not being able to start the car, close the top, windows, or electronics? Or is it just flooding you with messages via the app, email or instrument cluster?
I get these annoying emails, texts regarding our battery from our GLE but it never failed at doing anything. Starts, runs and operates as expected. With our car it's simply an unneeded threshold that is met and then gets busy notifying.
If yours is notifications/messages only I assume they will find nothing and eventually have a software update that will resolve this.
Last edited by Wolfman; Dec 1, 2022 at 02:22 PM.
I had one weird incident - I left the key in the car and when I tried to open the doors and the handles would not come out and I could not open at the same time as battery issues indicated.
However, when I finally got hold of the spare key it opened up and then started without trouble.
There is no doubt that there is an electrical gremlin - but what exactly I am also no sure. I also took it to my dealer they tested the battery and did all sorts of tests, but they were all inconclusive.
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Hopefully they will have sorted that out by 2023.
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Last edited by California John; Dec 16, 2022 at 08:01 PM.




If the battery voltage is relatively high, it may point to low voltage threshold levels that are set to high.
If the voltage is low, there may be excessive parasitic draw on the battery.
A simple test for parasitic draw is to clamp a DC clamp meter—capable of resolving to mA--around the large positive or negative battery wire and measure the current draw after the vehicle enters sleep mode. If memory serves, 40-50 mA is in the normal range for a vehicle in sleep mode.
If excessive draw is suspected, there are ways (measuring the voltage drop across individual fuses) to identify the bad actor.
I would love to have a R232 in the garage to test this out, but for now owning one is something I dream about---and sometime during waking hours too.


What I noticed today is that some of my saved settings like the steering wheel and seat returning to the logged in memory position plus the door locking options were changed. Several other options wiped too, but not too big a deal except for winnowing through the settings layers to find the fixes. This plus the remote start requiring the car to shut off before getting in to then immediately restart it are mildly annoying. Doesn't remotely (pun) take away from thoroughly enjoying the car.
My 992 GT3 has only a LiPo battery and I maintain that with a Lithium battery maintainer. My Taycan apparently has a physically small LiPo battery to supplement the main 93.4kWh battery, and messing with that small battery is a bad idea, based on the forums. I can't imagine why an SL63 would need a small LiPo battery to supplement the big ol' AGM battery under the trunk.
I've had the same experience as others with low/critical battery messages, e.g. when detailing the car. I keep it locked and on the AGM maintainer when not using it, with no messages since doing that.
The vehicle is equipped with an AGM technology
battery (Absorbent Glass Mat) or a lithium-
ion battery. Full vehicle functionality is
only guaranteed with an AGM battery or lithium-
ion battery. For safety reasons, Mercedes-
Benz recommends that you only use batteries
which have been tested and approved for your
vehicle by Mercedes-Benz.
Press lock function on key twice quickly and it will deactivate radio on key. This will extend battery and prevent any communications with key until key is pressed again.



