bpans

Today, my worst fear happened. My car gave a 12V Battery Critical state warning. According to my Mercedes app, it advised me to continue driving for 30 to 60 minutes to recharge. I tried to do this but then started receiving a number of error messages on the screen, ultimately prompting to ask me to stop driving. Because I didn't want to find myself stranded on the road, I decided to take the car back home. But as I was approaching home, the car gave a warning that it would shut down in 3 minutes. Upon reaching home, the car stopped halfway into the garage and shut down completely. It was so close to the wall that I couldn't exit from the driver's seat and had to get out from the passenger side. Unfortunately, the car would not start again. Eventually, I had to leave one car door open as, between the failure to start and the car's position, I wouldn’t have been able to get back in otherwise. This experience was a nightmare, and a painful reminder of the potential downsides of a car becoming entirely electric and high-tech.

I reached out to Mercedes roadside assistance and was rather disappointed by the service. It took twenty minutes just to get connected, and then another two hours for the towing company they contacted to arrive. In total, it was about 2.5 hours before I received help. I felt somewhat relieved that my car decided to stop in my garage rather than on a random roadside. The tow truck operator was able to reach the hood latch from the passenger side, open it, and use his jump starter to start the car. He was then able to reverse the car onto the flatbed. I followed him to the nearest dealership. Since the service center was closing soon, I had to contact my service specialist directly and explain the situation. She arranged for me to get a loaner car (an EQE SUV), which I could pick up from the sales office, which had later hours. However, when we arrived at the dealership, the jump starter battery of the tow truck operator was dead, so we had to charge it for a while before we could move the car into a parking space.

The whole ordeal was incredibly frustrating, and unlike any experience I'd had with my previous Lexus cars. I've owned three generations of Lexus RX and never had to call for a tow. We transitioned to the EQS only because Lexus has yet to release an appropriate Electric SUV. Now, we are questioning that decision.

Has anyone else had a similar issue? Could it be the battery or the alternator? If the problem was the battery, it should have recharged while I was driving. At this point, I'm unsure and am waiting for the dealership to provide further details.

Crito

You got a defective 12V battery. That just as easily could have happened in an ICE vehicle. It's really a problem with Mercedes' quality control. Some people here blame the Alabama facility but there are plenty of post here from people with new cars made in Germany that also have QC problems.

nath_h

This happened frequently in electric Jaguar world. There were two 12 volt batteries that would die and cause all sorts of problems with scary warning lights. Agree with post above...you've got a bad regular battery, that could have happened in any vehicle. I looked at the Lexus EV too...pretty underwhelming. Toyota has been slow to go BEV.

bpans

Thanks for the details. I have had 12V drain in my ICE cars before and the experience wasn't this scary. I cold still get in, open the hood or put the car in neutral with those cars. With EQS, it was super difficult. I am not sure if I could even open the door from outside if I accidentally closed it. And in my past cases, it is just a 12v battery draining which was fixed by simply jumpstarting and driving for 30 mins. Whereas, what I experienced is a complete failure of 12V so bit challenging.

Never thought how critical a 12V battery is for a full electric car. While the car has 80% charging on its main battery, interesting to see that it still depends on a 12V to operate these things. Maybe I am not getting this.

I will keep updating this thread.

Utopia Texas

Mercedes needs a manual lever on the dash board for the driver to pull and skip all the computer gadgetry for the main battery to recharge the dinky 12v battery.

Radman991

I recently had a 12v problem with lack of charging despite driving the car for hours. I got several warnings about critical low battery but never any warnings about the car shutting down. Took it to dealer and they replaced 12 v battery and has been perfect ever since.

bpans

Update:

After 3 days, the issue is still not fixed. The shop is suspecting that some fault is draining the 12V battery. They need to handover it to their EQ specialist. As next steps, looks like they will be running several diagnostics and sharing with Mercedes for review. I hear it will be a long process

I have an EQE SUV loaner at least though it’s no where near the same level as my fully loaded pinnacle trim of EQS580 .

Not feeling good. I hope it’s a just a one time fix and not going to require me for frequent shop visits.

bpans

No update on this. The car has been in the shop for almost a week. It got moved from regular service specialist to EQ specialist but they aren't making much progress. A lot of these seem like they will be coordinating the repair with the HQ. This is what we pay for buying a brand new tech. The service engineers here are not fully trained and not able to diagnose properly without help from HQ.