When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Does anybody know exactly how and when the EQE SUV charges its 12v battery? I’ve been receiving the same warnings even after having driven the car for over 5 hours and over 200 miles after the first warning.
I’m having trouble with my EQE SUV after we left it at the airport for two weeks simply parked, battery at 80%. Upon returning, I had a warning about the 12v battery being low. Now I’ve driven it every day since, normally and actively, and still the battery is “critical”. It would be wonderful to know if anyone knows how this car gets its 12v up, or was able to get this same situation resolved. Following the car’s own instructions to “drive for 20-30 minutes” doesn’t do anything, unless I’m supposed to be doing something specific.
I know there's no starter or alternator so driving for 30 to 60 minutes would be useless.
The reason the manual states to drive for 30-60 minutes is as follows: The 12V battery is charged by an onboard charger that runs off the main high-voltage (traction) battery. However, when you're not in "drive" mode, the contactors disconnect the high-voltage battery. This is to maximize the life of the traction battery. Thus, in order to charge the 12V battery, you'd need to at a minimum have the car in "ready" mode. However, if you just leave it in "ready" mode, it'll shut off and disconnect the contactors to the traction battery for safety reasons after a few minutes. Thus, the only way to ensure that the 12V battery gets enough charge is to drive it, such that the contactors stay engaged. I do suspect that if you engaged the remote climate control, it would also work, as the contactors have to close in order to permit the AC compressor to work.
Why not just let the 12V battery charge whenever? Great point - lead-acid batteries all eventually fail, and if the car kept closing the contactors to allow for a charge, over time, the drain to keep that battery charged overnight is going to become more problematic. I think this was one of the big issues the Rivian trucks had in terms of phantom battery drain, or at least it was suspected.
OP, sounds like you have a bad lead-acid battery. Have dealer replace, and you should be back on the road.
@bytemaster0 Contrary to your explanation, which sounds reasonable, there are reports of the car parked being for months when the 12v battery charge drops and then a day or two later being back up to normal. This would imply that there is additional logic to detect this condition, and charges the 12v battery even though the car has not been driven.
2023 EQE 500 SUV electric and 2024 Jaguar F-PACE SVR 5.0L
This is a prime example of why I'll never buy another Mercedes. That message is OBVIOUSLY for an internal combustion engine vehicle. Period. End of story. In order to correct this problem however, the first thing that has to happen is someone admitting they made a mistake. Only then will the problem be addressed and corrected. But since that'll never happen you'll never get a resolution and you'll just have to put up with this stoopid sheet forever.
@bytemaster0 Contrary to your explanation, which sounds reasonable, there are reports of the car parked being for months when the 12v battery charge drops and then a day or two later being back up to normal. This would imply that there is additional logic to detect this condition, and charges the 12v battery even though the car has not been driven.
If that's the case, that's fantastic. I'd expect that this could happen. Personally I haven't observed it, but it would be of course better if that occurred. In that case, I'd imagine that there is a fault in the battery itself. MB vehicles are pretty picky about the condition of lead-acid batteries. They really don't like the possibility of a hydrogen gas buildup.
Originally Posted by Crito
This is a prime example of why I'll never buy another Mercedes. That message is OBVIOUSLY for an internal combustion engine vehicle. Period. End of story. In order to correct this problem however, the first thing that has to happen is someone admitting they made a mistake. Only then will the problem be addressed and corrected. But since that'll never happen you'll never get a resolution and you'll just have to put up with this stoopid sheet forever.
I think you'll be disappointed by the software in many other brands as well. I'm sure you remember the TFL Car saga with the JLR Defender and its myriad displays of warnings, broken electronics, and 130-mile engine failure. The car totaled itself in just a few days. Whether or not MB is advising the error message for combustion vehicles, who knows. Few automotive manufacturers produce their own display/infotainment software, though for MB that's changing in 2025 with MBOS, supposedly, which will be in-house developed. At present time, there are months of turnaround time to have a change request made from the OE software supplier, then to have it validated (takes another few months), and then approved for release. For OP, the content of the error message doesn't really matter (it wouldn't to me), there's a fault that needs to be rectified by the dealer and let's hope their dealer will handle it in a satisfactory manner.
10-01-2023, 01:11 AM
12v Battery Charge Status Critical
