xtdoc777

I am very thankful to this forum for educating me on how to avoid a low 12V battery warning.

Previous posts have recommended always pressing the key lock button twice and keeping the key stored at least 20 feet away to allow the SL to “sleep” and keep the 12V car battery from discharging.

I followed this advice since I took delivery of my 2023 SL55 and have never had a low battery warning. But this week (a week I had not driven the SL much due to a hurricane) I locked the car one night using the phone app and not a double click of the key. The next morning I got the low 12V battery for the first time.

I then recharged the battery with a A0009822921 Mercedes trickle charger (a long drive to allow alternater charge probably would have accomplished the same thing) and now all is well. I will follow the proper key and locking procedure going forward.

ALL NEW R232 SL OWNERS: make sure to press the key lock button twice and keep the key stored at least 20 feet away from the SL and consider buying a trickle charger just in case.

silviang

I do not have any better experience than what you listed. I even took the car to the dealership to see if they can do anything - the feedback I got is that this is what it is and nothing else to do from their side.
This morning I got this warning again - after I drove it yesterday for 1 hour. This behavior seems very abnormal to me.

What can we do next to draw attention to this?

xtdoc777

As long as I double lock with the key and keep the key more than 20 feet away, all is fine. Seems weird that it was still low after an hour drive...maybe have them check your alternator to see if it is working properly.

Huncowboy

Ohh so this is why my door handles are extended (sometimes) when I walk to the car in the garage without the key in my pockets.

Streamliner

YES! This is VERY abnormal! And, to make matters worse, this abnormality has been a known issue since shortly after the 2021 S Class sedans were released. Wouldn’t we all wonder WHY MB continues to produce new vehicles that have this same issue, but they never tell their customers about it BEFORE they buy or lease the vehicles? There should be one of those WARNING stickers, conspicuously placed, advising potential customers that this new vehicle will require extraordinary measures for it to continue to operate properly. Simply treating it like every other vehicle you have ever owned will not suffice. Instead, they just wait until the customer gets the dreaded warning message—or MUCH worse—like the car completely going dead in the middle of a very busy highway— THEN they tell them about locking the car, moving the key away from the vehicle, etc.

I’d call that a big YES to being abnormal.

drgek

1. I don't take any "extraordinary measures" with my car and haven't had a battery warning since the first day I owned it. Personally, I wouldn't call double pressing the key fob an "extraordinary measure."
2. The issue you describe with the car going dead on a highway, wasn't that a fuel pump issue? Unacceptable to be sure, but not exactly a known battery issue. What was the final diagnosis on your S class?
3. It seems that all new cars with modern electronics suffer from battery issues. Ask any owner of a 992 911 with a lithium battery how much fun they are to maintain.
4. It would appear from your signature that you have been a loyal MB owner for years. It is unfortunate that the newer cars have not met your expectations.

bosscobra

Do you “double press” the key fob?

Streamliner

I was driving down a very congested area of Pacific Coast Highway, during noontime lunch traffic. My S580 was operating normally. Then, in the blink of an eye, a red message appeared on the dash saying something like “12 Volt battery low. Pull to side of road and charge. Do not shut off engine.” Within a minute or two and before I could even change lanes, the entire car died. The emergency flashers wouldn’t even work. Sure sounds like a battery problem and not a fuel pump to me.

I’m happy for you that you have not had issues, but the number of folks just HERE on MBWorld that have had problems with models released in 2021 & later is pretty alarming. Most folks don’t get caught in hairy situations like I did, but the potential is there and it shouldn’t be.

drgek

What was the ultimate diagnosis when the car was repaired?

Streamliner

Good question. I was so ELATED that the dealer kept the car for exactly 30 days, when I got it back, I don’t even think I looked at the invoice in detail. I pretty much hated the car from day one and in California where I live, when a new car hits 30 days out of service, the law says it’s a “lemon.” It took a few months, but MBUSA bought it back. I’ll try to find the invoice and take a look.

drgek

I'm glad for you that MB bought it back. A meaningless low battery warning on an app is one thing, your experience quite another.

Streamliner

Found it. Now I know why I didn’t pay much attention to it. Also, the SA wrote it up incorrectly. I was on a busy highway, but I was in slow, bumper-to-bumper traffic when it happened, not at “highway speeds.” Oh well, glad that fiasco is over with!

ughc43

Had good experiences with doing the same on my Gen 2 facelift R8, so after having the battery warning on my SL63 a few times despite following all the recommendations here and the battery running down faster than I'd like, I just had it swapped out with an Antigravity lifepo4 battery. Lighter, starts up faster, has more usable power (60Ah), and I can monitor the charge level easily. The phone app uses bluetooth and does support using it with multiple cars, you just connect to one of them at a time. Gear icon on the top right -> Bluetooth Device to change between cars.

The one that fits the SL63 is here in case anyone's curious: https://antigravitybatteries.com/pro...tive/ag-h6-rs/

Will update if I unexpectedly get a battery warning again with it sitting unused for less than two weeks or so.