E450(12v) under-charging? parasitic loads?
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Joined: Mar 2025
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2025 E450
E450(12v) under-charging? parasitic loads?
Hello, I have recently taken delivery of my first MB, a beautiful E450. However, I have found that the charging system seems to leave the 12V AGM battery significantly undercharged. I have a pretty good understanding of both batteries and charging systems. I am aware that some manufacturers reduced alternator output for various reasons. And, this is my wife's car that is generally driven about 10-15 minutes per start - but that is how she uses it. I have not found that longer drives improve the situation much. We recently began receiving app updates that the battery was low and I then had trouble getting it take a charge.
Details: The battery is rated 80ah. I have metering for my charger that accumulates how much is output per charge. When I put the charger on day after day, it routinely reports about a 20ah (equivalent) charge. Now, I do not expect that E450 or any car would do a full charge like a battery charger. If I charge once every two weeks, it will take 30ah+.
This is two problems. First, it is not good maintenance of the AGM battery and I would be replacing it often. Second, this highly electric vehicle is going to leave me stranded in a parking lot one day needing a charge.
I have joined the forum hoping that someone can shine a light on this issue. Does the MB system permit tweaks for charging rates and thresholds? Are there perpetual loads on the system that I should disable.
This has taken some time to understand and is killing the joy of this new car experience.
Thanks,
Details: The battery is rated 80ah. I have metering for my charger that accumulates how much is output per charge. When I put the charger on day after day, it routinely reports about a 20ah (equivalent) charge. Now, I do not expect that E450 or any car would do a full charge like a battery charger. If I charge once every two weeks, it will take 30ah+.
This is two problems. First, it is not good maintenance of the AGM battery and I would be replacing it often. Second, this highly electric vehicle is going to leave me stranded in a parking lot one day needing a charge.
I have joined the forum hoping that someone can shine a light on this issue. Does the MB system permit tweaks for charging rates and thresholds? Are there perpetual loads on the system that I should disable.
This has taken some time to understand and is killing the joy of this new car experience.
Thanks,
MBWorld God!
Joined: Dec 2019
Posts: 32,217
Likes: 6,275
Hello, I have recently taken delivery of my first MB, a beautiful E450. However, I have found that the charging system seems to leave the 12V AGM battery significantly undercharged. I have a pretty good understanding of both batteries and charging systems. I am aware that some manufacturers reduced alternator output for various reasons. And, this is my wife's car that is generally driven about 10-15 minutes per start - but that is how she uses it. I have not found that longer drives improve the situation much. We recently began receiving app updates that the battery was low and I then had trouble getting it take a charge.
Details: The battery is rated 80ah. I have metering for my charger that accumulates how much is output per charge. When I put the charger on day after day, it routinely reports about a 20ah (equivalent) charge. Now, I do not expect that E450 or any car would do a full charge like a battery charger. If I charge once every two weeks, it will take 30ah+.
This is two problems. First, it is not good maintenance of the AGM battery and I would be replacing it often. Second, this highly electric vehicle is going to leave me stranded in a parking lot one day needing a charge.
I have joined the forum hoping that someone can shine a light on this issue. Does the MB system permit tweaks for charging rates and thresholds? Are there perpetual loads on the system that I should disable.
This has taken some time to understand and is killing the joy of this new car experience.
Thanks,
Details: The battery is rated 80ah. I have metering for my charger that accumulates how much is output per charge. When I put the charger on day after day, it routinely reports about a 20ah (equivalent) charge. Now, I do not expect that E450 or any car would do a full charge like a battery charger. If I charge once every two weeks, it will take 30ah+.
This is two problems. First, it is not good maintenance of the AGM battery and I would be replacing it often. Second, this highly electric vehicle is going to leave me stranded in a parking lot one day needing a charge.
I have joined the forum hoping that someone can shine a light on this issue. Does the MB system permit tweaks for charging rates and thresholds? Are there perpetual loads on the system that I should disable.
This has taken some time to understand and is killing the joy of this new car experience.
Thanks,
MBWorld God!
Joined: Dec 2019
Posts: 32,217
Likes: 6,275
Here is the sub-forum that corresponds to the 2025 E 450 https://mbworld.org/forums/e-class-w214-284/
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,769
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
low voltage... chaos is next!!
Hello, I have recently taken delivery of my first MB, a beautiful E450. However, I have found that the charging system seems to leave the 12V AGM battery significantly undercharged. I have a pretty good understanding of both batteries and charging systems. I am aware that some manufacturers reduced alternator output for various reasons. And, this is my wife's car that is generally driven about 10-15 minutes per start - but that is how she uses it. I have not found that longer drives improve the situation much. We recently began receiving app updates that the battery was low and I then had trouble getting it take a charge.
Details: The battery is rated 80ah. I have metering for my charger that accumulates how much is output per charge. When I put the charger on day after day, it routinely reports about a 20ah (equivalent) charge. Now, I do not expect that E450 or any car would do a full charge like a battery charger. If I charge once every two weeks, it will take 30ah+.
This is two problems. First, it is not good maintenance of the AGM battery and I would be replacing it often. Second, this highly electric vehicle is going to leave me stranded in a parking lot one day needing a charge.
I have joined the forum hoping that someone can shine a light on this issue. Does the MB system permit tweaks for charging rates and thresholds? Are there perpetual loads on the system that I should disable.
This has taken some time to understand and is killing the joy of this new car experience.
Thanks,
Details: The battery is rated 80ah. I have metering for my charger that accumulates how much is output per charge. When I put the charger on day after day, it routinely reports about a 20ah (equivalent) charge. Now, I do not expect that E450 or any car would do a full charge like a battery charger. If I charge once every two weeks, it will take 30ah+.
This is two problems. First, it is not good maintenance of the AGM battery and I would be replacing it often. Second, this highly electric vehicle is going to leave me stranded in a parking lot one day needing a charge.
I have joined the forum hoping that someone can shine a light on this issue. Does the MB system permit tweaks for charging rates and thresholds? Are there perpetual loads on the system that I should disable.
This has taken some time to understand and is killing the joy of this new car experience.
Thanks,
Low battery charge and drain while parked are amazin' on factory-new cars... more recently we've come to realize poor voltage affects basic engine performance in addition to seeding CAN modules chaos.
Unstable voltage are proven to detunes a collection of MB platforms.
Is your 12V AGM battery charged by a conventional alternator or from the 3-Phase AC traction generator?
Last edited by CaliBenzDriver; Mar 6, 2025 at 07:35 PM.
