I can't charge my 12V battery?!
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Joined: Dec 2022
Posts: 173
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From: ukraine
S580 MAYBACH Z223
I can't charge my 12V battery?!
Hi everyone
About 2 or 3 days ago i purchased a Bosch batter charger (Bosch C70)
It has a mode for AGM batteries to keep it alive during the winter and also charge it.
And my vehicle also has 48V system.
When i connect the charger it takes very long time to go up to 25% to 50% on the indicator of the battery charger although it already has over 50% of 12v battery charge.
I left the car at charge at night and what i see on xentry was pretty weird. The car only charged the 12v battery to 70% (it was like 65% when i started the charging process)
And my 48v battery was at 70 or 73. After the charging procsess it was 86.5%
Soo.. What might be the problem? I really cant charge my 12v battery just due to this weird problem.
The DC to DC converter is a part that work according to its mind.
The problem might also be the charger not being powerful enough to charge my 12v battery , idk. its 10Amp , its a pretty decent device but it cannot make my car stay at a certain voltage. When i press the start button one it starts to drain the battery, even though its hooked up to a battery charger.
Thanks!
About 2 or 3 days ago i purchased a Bosch batter charger (Bosch C70)
It has a mode for AGM batteries to keep it alive during the winter and also charge it.
And my vehicle also has 48V system.
When i connect the charger it takes very long time to go up to 25% to 50% on the indicator of the battery charger although it already has over 50% of 12v battery charge.
I left the car at charge at night and what i see on xentry was pretty weird. The car only charged the 12v battery to 70% (it was like 65% when i started the charging process)
And my 48v battery was at 70 or 73. After the charging procsess it was 86.5%
Soo.. What might be the problem? I really cant charge my 12v battery just due to this weird problem.
The DC to DC converter is a part that work according to its mind.
The problem might also be the charger not being powerful enough to charge my 12v battery , idk. its 10Amp , its a pretty decent device but it cannot make my car stay at a certain voltage. When i press the start button one it starts to drain the battery, even though its hooked up to a battery charger.
Thanks!
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GLE 580
Let us know what happens with both state of charge %s when leaving it on longer than overnight. I'm surprised that the DC to DC would increase the 48v beyond 80%. I would just assume that the BMS would keep the 48v around 80% for longevity, and then only charge the 12v to 100%.
Last edited by wildta; Jan 11, 2025 at 05:55 AM.
Thread Starter
Member
Joined: Dec 2022
Posts: 173
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From: ukraine
S580 MAYBACH Z223
Let us know what happens with both state of charge %s when leaving it on longer than overnight. I'm surprised that the DC to DC would increase the 48v beyond 80%. I would just assume that the BMS would keep the 48v around 80% for longevity, and then only charge the 12v to 100%.
something over 1 year or so
im connecting the charger to the battery terminals under the hood
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Joined: Aug 2019
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From: New Jersey
2023 S580, 2025 GLE450, 2025 AMG SL43
I had the exact same problem with a MB brand charger. After some research I purchased a CTEK 40-206 MXS 5.0 charger from Amazon and the issue is fixed. Battery charges full overnight.
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223.168 & 213.012 & 906.633 & 214.005
MB branded chargers are usually made by CTEK, not sure if the early ones are perfect for AGM batteries. Would be interesting to know the difference between your two chargers.
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From: New Jersey
2023 S580, 2025 GLE450, 2025 AMG SL43
I know they are made by CTEK which is why I was pissed off it didn't work. This new one which I specified the part number indicates fully charged and the MB Connect shows fully charged. Not sure what else to tell you except I no longer have the issue.
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The MB app just shows "charged" for the cars in our family, I've never seen it show "fully charged" even after the car battery had been fully charged with a CTEK. I don't think we would know if Xentry would show 70% or 100% SOC in this case.
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W167 2021 GLE63S, W223 2022 S580
SOC vs volts?
Just to clarify, I was hoping you would have access to Xentry diagnosis prints like TSA shared. He felt he had a problem but his car may have behaved just like yours, perhaps there is none.
The MB app just shows "charged" for the cars in our family, I've never seen it show "fully charged" even after the car battery had been fully charged with a CTEK. I don't think we would know if Xentry would show 70% or 100% SOC in this case.
The MB app just shows "charged" for the cars in our family, I've never seen it show "fully charged" even after the car battery had been fully charged with a CTEK. I don't think we would know if Xentry would show 70% or 100% SOC in this case.
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I did not pay attention to the voltage figure. Not sure how low the battery voltage could be when loaded, assume engine was not running but diagnosis ongoing meaning most of the car fully active. There should be an amps reading too but I did not find it from the posted figures.
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From: ukraine
S580 MAYBACH Z223
and in that photo my charger is also hooked up to the car. I sometimes don’t even think it’s charging. It’s 10amp or so but it’s not charging at the full 10amps. It makes no difference with on and off the car while the car is in accessory mode.
I need to turn off the car and lock it to make that thing charge up the car. I checked the amperage of the car while it’s on acc mode , it consumes about 20-30 amps. The charger is only 10 amps. I think it’s not enough to supply this car. I need a 100 amp one.
I did not pay attention to the voltage figure. Not sure how low the battery voltage could be when loaded, assume engine was not running but diagnosis ongoing meaning most of the car fully active. There should be an amps reading too but I did not find it from the posted figures.
also today I started up the engine and charged it up to 90%. i still can’t understand why the charger is only taking it up to 73 and not over it??
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2023 S580 (current), 2019 Range Rover HSE V6 (current),2021 S580, 2018 S560 4Matic, 2015 S550 4Matic
What type battery do we have in the W223? Is it a AGM or lithium Ion. I looked in my owner manual but can’t tell…..
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From: ukraine
S580 MAYBACH Z223
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