12 VOLT ACCESSORY BATTERY???
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Junior Member
Joined: Dec 2023
Posts: 27
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EQS Sedan
12 VOLT ACCESSORY BATTERY???
This is my first problem after about 18 months of ownership (leased) of our EQS 450+ sedan. The 'phone app', MY MERCEDES, displayed a RED triangle and the text 'battery critical'. Clicking on that leads to a message about the 12 volt battery being critically low. Note that there was no warning or display on the cars instrument panel. Everything seemed to work just fine. Well after a couple of weeks with the warning on my phone app, I took it to the dealer. No problemo..... they replaced the 12 volt battery and everything was / is fine.... just like it always was, EXCEPT the display with the warning is still on my phone app. The dealer said it would clear itself in a few days. It hasn't. Calling MY MERCEDES, which was a challenge, I was told it was a dealer problem. Going back to the dealer, they said it's a problem with the app.
Any thoughts??? The car operates fine but my wife always asks if it's going to strand her someplace.
Any thoughts??? The car operates fine but my wife always asks if it's going to strand her someplace.
MBWorld Fanatic!
Joined: Dec 2006
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From: Europe
223.168 & 213.012 & 906.633 & 214.005
What does the app say about the 12 V battery now at the services page?
It could be the car has not sent all status data to the MB Me server, perhaps only sending the critical battery alert but not any subsequent clear message. It could be the server confused, not clearing the info towards the app. It could be the app getting up-to-date info but not clearing the alert. You could play with the car remotely, change charging settings, set heating on/off to make the car update status data to the server. You could delete all temporary data from the app, perhaps reinstall too. Unfortunately no way to reset the MB Me server.
It could be the car has not sent all status data to the MB Me server, perhaps only sending the critical battery alert but not any subsequent clear message. It could be the server confused, not clearing the info towards the app. It could be the app getting up-to-date info but not clearing the alert. You could play with the car remotely, change charging settings, set heating on/off to make the car update status data to the server. You could delete all temporary data from the app, perhaps reinstall too. Unfortunately no way to reset the MB Me server.
Super Member
Joined: Dec 2014
Posts: 821
Likes: 185
From: New England/Florida
2005 SL 500. 2015 S550. 2016 GLE400 2018 S560
I had a similar problem with the 12 volt battery and getting the critical low warning. Like you the dealer replaced the battery and ever since all is well, the warning cleared and occasionally I get a partially charged warning if I let the car sit unused for a while. It self charges itself within a day or two. Service adviser said to put trickle charger on it for extended downtime periods.
Member
Joined: Jan 2023
Posts: 187
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EQE 350 4matic
Something to note here is that the HV battery does not maintain the LV battery below 15%; why? I dunno.
If your HV state of charge is over 20%, the DC-DC bus will maintain LV (12V and 40V) systems. The app message is triggered from the vehicle if the vehicle hasn't been driven for an extended period of time. Also, I hate MBUSA's practice of recommending 12V trickle chargers to MB workshops, especially given entering service mode does not deactivate the DC-DC bus and ruins the LV maintenance system in EQ products.
If your HV state of charge is over 20%, the DC-DC bus will maintain LV (12V and 40V) systems. The app message is triggered from the vehicle if the vehicle hasn't been driven for an extended period of time. Also, I hate MBUSA's practice of recommending 12V trickle chargers to MB workshops, especially given entering service mode does not deactivate the DC-DC bus and ruins the LV maintenance system in EQ products.
Super Member
Joined: Jan 2022
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When I am cleaning the interior or otherwise will have the doors open for a long time (like when I take it in for service), I always reach up and turn off the main interior lights to protect my 12V battery as much as possible. I have received no warnings. Maybe this has helped?
Super Member
Joined: Dec 2014
Posts: 821
Likes: 185
From: New England/Florida
2005 SL 500. 2015 S550. 2016 GLE400 2018 S560
Although being told by two different service advisors from 2 different dealers to put it on a trickle charger for prolonged periods, I have been hesitant to do so. I figured if the car will maintain it on its own why add another level of complexity. When my car is in downtime I am 1400 miles away and obviously couldn’t do anything if the charger went on the fritz.
Since getting a replacement 12 v battery, the car has maintained its state of charge without me doing anything. I suspect the original 12 v battery may have failed because the car sat at the Baltimore VPC for 4 months before they released it to the dealer.
Since getting a replacement 12 v battery, the car has maintained its state of charge without me doing anything. I suspect the original 12 v battery may have failed because the car sat at the Baltimore VPC for 4 months before they released it to the dealer.
Super Member
Joined: Dec 2022
Posts: 756
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From: Sweden
2023 EQE SUV 500 4Matic
Interesting info about the 15%! I’m even more interested about the comment above. How have you come to learn this? My dealer here in Sweden recommended trickle charging to me when I parked my car for 5 months earlier this year. So far, I don’t think I’ve ruined my dc to dc charger, as it’s still behaving like it’s supposed to. Furthermore, they have trickle chargers on all their EQ cars in the showroom.
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Super Member
Joined: Jan 2022
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Interesting info about the 15%! I’m even more interested about the comment above. How have you come to learn this? My dealer here in Sweden recommended trickle charging to me when I parked my car for 5 months earlier this year. So far, I don’t think I’ve ruined my dc to dc charger, as it’s still behaving like it’s supposed to. Furthermore, they have trickle chargers on all their EQ cars in the showroom.
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Member
Joined: Jan 2023
Posts: 187
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EQE 350 4matic
The way DC DC converter degrades is in terms of efficiency. So it will use more power to boost the 12V, wasting the rest as heat. I've been able to nail the 15% HV SoC value from running tests; my old job was designing and testing EV hardware platforms. The original idea was to have on-ground power like with aircraft, but it looks like MB decided not to commit to doing it down the trickle charger route.
MBWorld Fanatic!
Joined: Dec 2006
Posts: 6,501
Likes: 336
From: Europe
223.168 & 213.012 & 906.633 & 214.005
Something to note here is that the HV battery does not maintain the LV battery below 15%; why? I dunno.
If your HV state of charge is over 20%, the DC-DC bus will maintain LV (12V and 40V) systems. The app message is triggered from the vehicle if the vehicle hasn't been driven for an extended period of time. Also, I hate MBUSA's practice of recommending 12V trickle chargers to MB workshops, especially given entering service mode does not deactivate the DC-DC bus and ruins the LV maintenance system in EQ products.
If your HV state of charge is over 20%, the DC-DC bus will maintain LV (12V and 40V) systems. The app message is triggered from the vehicle if the vehicle hasn't been driven for an extended period of time. Also, I hate MBUSA's practice of recommending 12V trickle chargers to MB workshops, especially given entering service mode does not deactivate the DC-DC bus and ruins the LV maintenance system in EQ products.
I don't get your point on the 12 V chargers. As mentioned above, a standard procedure to hook a high power 12 V charger at service to take care of the power consumption when the diagnosis tool is used etc. Do you mean the workshop could use a HV charger instead? Perhaps so but they don't have that for all cars being serviced and I believe the safety rules do not allow that either.
Super Member
Joined: Dec 2022
Posts: 756
Likes: 226
From: Sweden
2023 EQE SUV 500 4Matic
Don't even think about using one of those trickle chargers that come with a plug for a 12v socket. For starters, the car needs to be powered on for that circuit to close.
