Yes - the 12V battery is automatically recharged by the high-voltage battery
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Yes - the 12V battery is automatically recharged by the high-voltage battery
There have recently been several posts where people have questioned whether or not an EQS's 12V battery is recharged automatically from the high-voltage battery if an EQS is parked, unattended, for several days or weeks. I can confirm (once again) that this is, indeed, the case.
I recently left my car (a 2023 EQS 580 SUV) unattended for more than 10 days, but checked the (high-voltage battery) charging level and the 12V battery status daily, remotely using the "Mercedesme Connect" app. Here are the results:
I recently left my car (a 2023 EQS 580 SUV) unattended for more than 10 days, but checked the (high-voltage battery) charging level and the 12V battery status daily, remotely using the "Mercedesme Connect" app. Here are the results:
- Date ..... Charging level .. 12V battery status
- June 1 ... 36% .................. fully charged
...
- June 7 ... 36% .................. fully charged
- June 8 ... 36% .................. partially charged
- June 9 ... 36% .................. partially charged
- June 10 . 36% .................. partially charged
- June 11 . 36% .................. partially charged
- June 12 . 36% .................. partially charged
- June 13 . 35% .................. fully charged
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Makes very much sense to use the high voltage battery on an EV to charge the 12 V battery when needed, at least to any decent high voltage battery SOC (anyone willing to try if it still works at 10% SOC or so?).
This behaviour however must have changed at some point as we have many cases where the 12 V battery got fully discharged. Would be useful to know when exactly the change was made. A bit dangerous if cars with old SW still exist and owners assume the car taking care of the 12 V battery. If it does not come with some MBUX update, the owner might not even be able to verify his/her car's behaviour.
This behaviour however must have changed at some point as we have many cases where the 12 V battery got fully discharged. Would be useful to know when exactly the change was made. A bit dangerous if cars with old SW still exist and owners assume the car taking care of the 12 V battery. If it does not come with some MBUX update, the owner might not even be able to verify his/her car's behaviour.
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I hope the high voltage batteries act as a maintainer for the 12 volt. On our I Pace, they do not, and the 2 12 volts on board tend to have problems and cause all sorts of fault codes. My older MB CL550 is power hungry, and causes one of its two batteries to drain when left unattended for a while. A car as power hungry as a 580 that has so many electronic gizmos to run will need great battery management to not have problems down the road a few years.
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Makes very much sense to use the high voltage battery on an EV to charge the 12 V battery when needed, at least to any decent high voltage battery SOC (anyone willing to try if it still works at 10% SOC or so?).
This behaviour however must have changed at some point as we have many cases where the 12 V battery got fully discharged. Would be useful to know when exactly the change was made. A bit dangerous if cars with old SW still exist and owners assume the car taking care of the 12 V battery. If it does not come with some MBUX update, the owner might not even be able to verify his/her car's behaviour.
This behaviour however must have changed at some point as we have many cases where the 12 V battery got fully discharged. Would be useful to know when exactly the change was made. A bit dangerous if cars with old SW still exist and owners assume the car taking care of the 12 V battery. If it does not come with some MBUX update, the owner might not even be able to verify his/her car's behaviour.
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I think all the EV manufacturers have faced and adresses this. It was not recognized early by many of them. Porsche's were bricking from 70mph, Audi's too. And we had several early problems with the EQS 12v battery....all of which made some of us (me included) extremely paranoid about the 12v battery. The issues for most manufacturers have now been solved with software and drivetrain management updates. I am very happy to see the OP's post and know that the 12v battery is now being charged by the HV battery as needed.
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No, I have always seen (in the app) the 12V battery's status as either "charged" or "partially charged". To my knowledge, there has never been a way to see the exact charging level (beyond either "charged" or "partially charged") of the 12V battery.
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There have recently been several posts where people have questioned whether or not an EQS's 12V battery is recharged automatically from the high-voltage battery if an EQS is parked, unattended, for several days or weeks. I can confirm (once again) that this is, indeed, the case.
I recently left my car (a 2023 EQS 580 SUV) unattended for more than 10 days, but checked the (high-voltage battery) charging level and the 12V battery status daily, remotely using the "Mercedesme Connect" app. Here are the results:
I recently left my car (a 2023 EQS 580 SUV) unattended for more than 10 days, but checked the (high-voltage battery) charging level and the 12V battery status daily, remotely using the "Mercedesme Connect" app. Here are the results:
- Date ..... Charging level .. 12V battery status
- June 1 ... 36% .................. fully charged
...
- June 7 ... 36% .................. fully charged
- June 8 ... 36% .................. partially charged
- June 9 ... 36% .................. partially charged
- June 10 . 36% .................. partially charged
- June 11 . 36% .................. partially charged
- June 12 . 36% .................. partially charged
- June 13 . 35% .................. fully charged
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From: New England/Florida
2005 SL 500. 2015 S550. 2016 GLE400 2018 S560
There have recently been several posts where people have questioned whether or not an EQS's 12V battery is recharged automatically from the high-voltage battery if an EQS is parked, unattended, for several days or weeks. I can confirm (once again) that this is, indeed, the case.
I recently left my car (a 2023 EQS 580 SUV) unattended for more than 10 days, but checked the (high-voltage battery) charging level and the 12V battery status daily, remotely using the "Mercedesme Connect" app. Here are the results:
I recently left my car (a 2023 EQS 580 SUV) unattended for more than 10 days, but checked the (high-voltage battery) charging level and the 12V battery status daily, remotely using the "Mercedesme Connect" app. Here are the results:
- Date ..... Charging level .. 12V battery status
- June 1 ... 36% .................. fully charged
...
- June 7 ... 36% .................. fully charged
- June 8 ... 36% .................. partially charged
- June 9 ... 36% .................. partially charged
- June 10 . 36% .................. partially charged
- June 11 . 36% .................. partially charged
- June 12 . 36% .................. partially charged
- June 13 . 35% .................. fully charged
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From: Brookshire, Texas & Cat Spring, Texas
2019 SL550/2023 EQS 580 SUV
The 12v battery is not like a regular 12v starter battery in a IC vehicle. I believe in the EQS it is much smaller in size and capacity.
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I have not personally opened up the hood on my EQS so I can’t verify the size of the battery but I asked my service manager that question. First response was smaller battery, then I was told it’s pretty much the same size as starter battery. So basically I have no idea what size it actually is.
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I've read that some EV BMS stop charging the 12V when the high volt battery's SOC gets too low. Would be interesting to see if that's the case with Mercedes too.
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From: Brookshire, Texas & Cat Spring, Texas
2019 SL550/2023 EQS 580 SUV
I have not personally opened up the hood on my EQS so I can’t verify the size of the battery but I asked my service manager that question. First response was smaller battery, then I was told it’s pretty much the same size as starter battery. So basically I have no idea what size it actually is.
720 Amp hours Cold Cranking is big but a 70 Amp hour capacity is very small. Someone correct me if I am incorrect. I get some of this mixed up…
Last edited by Utopia Texas; Jun 17, 2023 at 05:56 PM.
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From: Brookshire, Texas & Cat Spring, Texas
2019 SL550/2023 EQS 580 SUV
I do not see why one would need a 700+ Ah battery, as you do not need to power a starter motor for a large engine. The EQS 12V battery only runs the various computers, displays, etc., and perhaps the heating/cooling system. Starting the car is turning the multiple computers on.
Last edited by Utopia Texas; Jun 17, 2023 at 10:14 PM.
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Some confusion with figures here. It is not 700 Ah but 700 A current delivery capacity (for ICE cold start cranking). 70 Ah is the battery capacity and this size is used by many Mercedes ICE cars (gasoline engines/no cold country). Starting the ICE car needs a lot of current, not that much energy (Ah) as starting takes a short time.
The EQS does not need this high peak current capability. High power accessories are run from the high voltage battery (heating circuit, AC compressor etc.).
The EQS does not need this high peak current capability. High power accessories are run from the high voltage battery (heating circuit, AC compressor etc.).
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My mistake
Some confusion with figures here. It is not 700 Ah but 700 A current delivery capacity (for ICE cold start cranking). 70 Ah is the battery capacity and this size is used by many Mercedes ICE cars (gasoline engines/no cold country). Starting the ICE car needs a lot of current, not that much energy (Ah) as starting takes a short time.
The EQS does not need this high peak current capability. High power accessories are run from the high voltage battery (heating circuit, AC compressor etc.).
The EQS does not need this high peak current capability. High power accessories are run from the high voltage battery (heating circuit, AC compressor etc.).
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From: New England/Florida
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To the OP. Do you recall how long your car was at partially charged status till it went to fully charged. On your list it only took 5 days. Has it taken longer than that? I’m at my second go around of partially charged status. Reason I’m asking is my car has been sitting at partially charged status for over a week with my high voltage battery at 79% SOC. The first time my battery went from partially charged to fully charged was same day I preconditioned the cabin temp as per recommendation of my service department. Don’t know if it was a coincidence or not. In any event I haven’t done anything to the car in over 2 weeks and it still sits at partially charged.
Last edited by Radman991; Jun 20, 2023 at 12:39 PM.
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It might depend on how discharged your 12V battery happens to be (the app says only "charged" or "partially charged". Or it might depend on the model/age of the vehicle (mine is a 2023 EQS 580 SUV), or the software version...
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Yes - that's how long it took. This has also happened to me a couple of other times (when I've left my vehicle unattended for a few weeks). One time before, the 12V battery was "partially charged" (according to the app) for only 3 days. The other time, I don't remember, but it was less than 1 week.
It might depend on how discharged your 12V battery happens to be (the app says only "charged" or "partially charged". Or it might depend on the model/age of the vehicle (mine is a 2023 EQS 580 SUV), or the software version...
It might depend on how discharged your 12V battery happens to be (the app says only "charged" or "partially charged". Or it might depend on the model/age of the vehicle (mine is a 2023 EQS 580 SUV), or the software version...
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Well, I’m over 2 weeks and app still read’s partially charged. I would have thought it would have recharged itself by this time.
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From: New England/Florida
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Hmmm, your software is fairly new as I believe the newest is E330.xx, so not far behind. So for that reason, I think software isn't the cause. Unless OP has E330.xx and needs E330.xx to have this function?
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It could be the SW version of other control units, those that take care of battery charging (diag tool needed for that additional info).
