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I recently have started to experience high voltage hybrid battery drain. The car sits in front of my house running nothing inside it’s locked however something is eating up the battery.
2025 AMG E 53; 2018 GLC300 4Matic; 2003 360 Modena
Immediate thought - is the car close enough to your physical key or digital keys (phone / watch) that it is keeping the car awake? Do you have a battery tender handy that could be connected to the 12 volt battery to see if it stems the drain?
Immediate thought - is the car close enough to your physical key or digital keys (phone / watch) that it is keeping the car awake? Do you have a battery tender handy that could be connected to the 12 volt battery to see if it stems the drain?
thanks for your answer, the physical keys are inside a faraday pouch for the security. they shouldn’t be communicating with the car. about the 12v battery, I don’t have such device but the battery health shows okay and fully charged.
2025 AMG E 53; 2018 GLC300 4Matic; 2003 360 Modena
The 400v system keeps the 12v charged under the right parameters. My thought was that something is draining the 12v battery (as that is responsible for the consumables much like a ICE car) and the 400v architecture is charging the 12v and that's why you show a healthy 12v battery that is fully charged.
The 400v system keeps the 12v charged under the right parameters. My thought was that something is draining the 12v battery (as that is responsible for the consumables much like a ICE car) and the 400v architecture is charging the 12v and that's why you show a healthy 12v battery that is fully charged.
You’re right however nothing is plugged in the car and the wireless charging pad is also empty. This problem has recently started maybe like since two days. I am confused. Already created an appointment to the dealer lets see how it goes.
The 400v system keeps the 12v charged under the right parameters. My thought was that something is draining the 12v battery (as that is responsible for the consumables much like a ICE car) and the 400v architecture is charging the 12v and that's why you show a healthy 12v battery that is fully charged.
I’ve monitored the 12V battery and it seems that it gets drained and the high voltage battery charges it constantly. That’s why my hybrid battery gets drained. So the question is what is eating up the 12V battery now? MBUX maybe?
I’ve monitored the 12V battery and it seems that it gets drained and the high voltage battery charges it constantly. That’s why my hybrid battery gets drained. So the question is what is eating up the 12V battery now? MBUX maybe?
Parasitic drain is one of the most annoying ones, is they key stored close to the vehicle by chance? It might be keeping the vehicle awake.
I keep the keys inside a faraday pouch all the time.
So I came back from the dealer this morning, they've updated the software of the air climate control module and the BMS. I'll wait for some more time to see if that fixed the issue.
Last edited by ofozdemir; Jun 4, 2025 at 07:04 AM.
I keep the keys inside a faraday pouch all the time.
So I came back from the dealer this morning, they've updated the software of the air climate control module and the BMS. I'll wait for some more time to see if that fixed the issue.
On other MB models (recent ones) it was the door module draining the battery.
Quick update to the topic, I left the car to the mb dealer and they’ve inspected the issue for a week and couldn’t find the source despite the fact that they’ve updated all of the module softwares. I’m informed today that, they’ve contacted with the germany factory and expecting an expert on site to further debug the problem which dealer cannot have access to do. I’ve asked is this the first time you’re having this issue and they said yes with this new model year. I’m mentally on the edge of giving up on my beloved car.
Quick update to the topic, I left the car to the mb dealer and they’ve inspected the issue for a week and couldn’t find the source despite the fact that they’ve updated all of the module softwares. I’m informed today that, they’ve contacted with the germany factory and expecting an expert on site to further debug the problem which dealer cannot have access to do. I’ve asked is this the first time you’re having this issue and they said yes with this new model year. I’m mentally on the edge of giving up on my beloved car.
Was seriously hoping it was just the door module, turns out it is more complicated than expected.
today I was checking the me app and I saw that the ignition was on hood was open for the whole day which makes me assume that the factory was remotely connected to the car and having a long debug session. I lost the connection in the afternoon, hoping to hear more from the dealer soon.
today I was checking the me app and I saw that the ignition was on hood was open for the whole day which makes me assume that the factory was remotely connected to the car and having a long debug session. I lost the connection in the afternoon, hoping to hear more from the dealer soon.
I've got a call from the dealer stating that the factory finished their remote debugging/inspection session. They've updated all of the modules' software (in total of 82 modules) and they've applied a patch to the MBUX and/or somewhere else (as far as they know for now). The root cause as far as they know is as follows;
Something was keeping the car awake, it could be MBUX or it could be one of the modules hence the 12V battery gets drained and the high voltage battery was charging the 12V battery constantly.
I've got a call from the dealer stating that the factory finished their remote debugging/inspection session. They've updated all of the modules' software (in total of 82 modules) and they've applied a patch to the MBUX and/or somewhere else (as far as they know for now). The root cause as far as they know is as follows;
Something was keeping the car awake, it could be MBUX or it could be one of the modules hence the 12V battery gets drained and the high voltage battery was charging the 12V battery constantly.
So they don't actually know the root cause. Something was keeping the car awake does not qualify as a root cause. Kind of like saying something was keeping the person from breathing as a root cause of death.
Hopefully, they got that something to stop keeping the car awake.
So they don't actually know the root cause. Something was keeping the car awake does not qualify as a root cause. Kind of like saying something was keeping the person from breathing as a root cause of death.
Hopefully, they got that something to stop keeping the car awake.
I had the same reaction. I’m hoping to have a detailed precise explanation when I’m there to pickup the car.
So they don't actually know the root cause. Something was keeping the car awake does not qualify as a root cause. Kind of like saying something was keeping the person from breathing as a root cause of death.
Hopefully, they got that something to stop keeping the car awake.
I dont get it, on other MBs, it was resolved with an update to the door module, I am not sure what is causing the drain on the W214.
dealer have updated all the modules software with the help of factory. this ultimately triggered anti-thieft protection and locked the whole car and the factory remotely connected once again and unlocked the car.
right after I picked up my car, I’ve received an OTA update for the connectivity module which I suspect is the root cause of the issue and was keeping the car awake.
I didn’t observed any drain neither in 12V nor High voltage battery.
Last edited by ofozdemir; Jun 20, 2025 at 03:36 PM.
dealer have updated all the modules software with the help of factory. this ultimately triggered anti-thieft protection and locked the whole car and the factory remotely connected once again and unlocked the car.
right after I picked up my car, I’ve received an OTA update for the connectivity module which I suspect is the root cause of the issue and was keeping the car awake.
I didn’t observed any drain neither in 12V nor High voltage battery.
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