Phantom drain question
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From: Louisville, KY
2023 EQE350 4MATIC, 2023 EQE 350 4MATIC SUV, 2015 E250 BlueTEC 4MATIC, 1995 E300 Diesel
Phantom drain question
All,
My sedan has started a phantom drain problem, as of about a week or two ago. It has been pretty cold, and the 12V battery has shown itself to be "partially discharged" in a couple of cases. However, I'm losing 1-2% per day, which is very different than the average 0% per day I normally see. I can't find a particular rhyme or reason for it, though I do wonder if something is running/not turning off properly. It's around a 50W constant drain, based on percentage. Anyone else have the same? My dad, who passed away 2 weeks ago, has an X294 and it has sat for 2 months with just a 2% drain over that period of time. Our X294 doesn't seem to be doing this either. Thoughts?
My sedan has started a phantom drain problem, as of about a week or two ago. It has been pretty cold, and the 12V battery has shown itself to be "partially discharged" in a couple of cases. However, I'm losing 1-2% per day, which is very different than the average 0% per day I normally see. I can't find a particular rhyme or reason for it, though I do wonder if something is running/not turning off properly. It's around a 50W constant drain, based on percentage. Anyone else have the same? My dad, who passed away 2 weeks ago, has an X294 and it has sat for 2 months with just a 2% drain over that period of time. Our X294 doesn't seem to be doing this either. Thoughts?
Last edited by bytemaster0; Feb 21, 2025 at 03:06 PM.
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Low temperatures have a direct effect on batteries. The Louisville minimum temperatures have been quite a bit below average. It also takes more energy to warm the battery to operating temperature when you use it.
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From: Louisville, KY
2023 EQE350 4MATIC, 2023 EQE 350 4MATIC SUV, 2015 E250 BlueTEC 4MATIC, 1995 E300 Diesel
Also, all three of our EQEs are here in Louisville and are equally cold. One of them has only seen 2% battery level drop in 2 months, my sedan 2% in one day.
Last edited by bytemaster0; Feb 21, 2025 at 07:10 PM.
Thread Starter
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From: Louisville, KY
2023 EQE350 4MATIC, 2023 EQE 350 4MATIC SUV, 2015 E250 BlueTEC 4MATIC, 1995 E300 Diesel
Thread Starter
MBWorld Fanatic!
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From: Louisville, KY
2023 EQE350 4MATIC, 2023 EQE 350 4MATIC SUV, 2015 E250 BlueTEC 4MATIC, 1995 E300 Diesel
So, as an update, I'm losing 1.0 kWh every 16.5 hours. Seems to be independent of temperature, as it has warmed up a lot since I first noticed the issue. That corresponds to a 60W constant drain. 1.45 kWh every 24 hours is equivalent to losing over 5 miles of range. I've tried resetting what I could from my end, but the issue continues. I've left the car plugged in, and every 16.5 hours, it starts charging again for exactly 6 minutes, and exactly 1.0 kWh.
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From: Sweden
2023 EQE SUV 500 4Matic
I missed your comment about your father earlier. My condolences on your loss.
If it's not the 12v battery that's causing this, my next guess would be that one (or or more) of the Lithium cells in the HV battery has collapsed/shorted. The whole battery charge level goes down gradually because the BMS is constantly using the good cells to try to balance the failed cell that will not hold a charge.
If this is the case, then the failed cell is likely overheating and can present a fire risk.
I would prioritize getting the car to the dealer -- even leaving it there early, if you have to wait several days for an appointment.
If it's not the 12v battery that's causing this, my next guess would be that one (or or more) of the Lithium cells in the HV battery has collapsed/shorted. The whole battery charge level goes down gradually because the BMS is constantly using the good cells to try to balance the failed cell that will not hold a charge.
If this is the case, then the failed cell is likely overheating and can present a fire risk.
I would prioritize getting the car to the dealer -- even leaving it there early, if you have to wait several days for an appointment.
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The power consumption is most likely due to the SmartKey system looking for a key. It can be disabled via the SmartKey fob.
From the EQE Operators Manual page 65
From the EQE Operators Manual page 65
You can also deactivate the function of the SmartKey to reduce the energy consumption of
the SmartKey if you do not use the vehicle or a SmartKey for an extended period of time.
the SmartKey if you do not use the vehicle or a SmartKey for an extended period of time.
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From: Louisville, KY
2023 EQE350 4MATIC, 2023 EQE 350 4MATIC SUV, 2015 E250 BlueTEC 4MATIC, 1995 E300 Diesel
I missed your comment about your father earlier. My condolences on your loss.
If it's not the 12v battery that's causing this, my next guess would be that one (or or more) of the Lithium cells in the HV battery has collapsed/shorted. The whole battery charge level goes down gradually because the BMS is constantly using the good cells to try to balance the failed cell that will not hold a charge.
If it's not the 12v battery that's causing this, my next guess would be that one (or or more) of the Lithium cells in the HV battery has collapsed/shorted. The whole battery charge level goes down gradually because the BMS is constantly using the good cells to try to balance the failed cell that will not hold a charge.
As for a shorted cell, the thought had crossed my mind. However, I think we have pouch cells in our battery modules, which means it's relatively simple to add per-cell monitoring to the BMS. I'm very certain that a shorted cell would immediately trigger a dire warning on the display - no way the car would try to charge it, and it'd basically brick itself. However, I'm wary enough of the two reported EQE fires that I'm more concerned about it than if it were a typical EV battery, if only because fires have occurred in the past, though extremely rare. I'm definitely not going to sit around on it.
The one timing thing that does coincide very much is when Tesla chargers started showing up. I know that the display of supercharger sites is dependent on the Mercedes Me profile option for J3400 adapter. The car itself knows nothing about the adapter. So, maybe it's constantly being updated/checking to see the list of updated sites in the background? I'm going to disable adapter support to see if that has any effect. Should be an easy test. I'm also not unconvinced that our SUV is having a bit of a drain too in these colder temps, will verify that by leaving it plugged in also. We have a Sense Solar energy monitor installed, and in addition to the MB app notifications, it's very easy to tell when the car starts and stops charging in the power history graph.
I'd agree with this, but I've had the car for almost 2 years, and this just started happening within the last month. I'll try that out as well, after I disable the J3400 adapter option.
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It sounds like we are having similar issues. I have a 2023 EQS 580 and I've been experiencing significant HVB drain over the past week or so. Last night I lost ~ 4% of the battery in 12 hours--went to bed with 59% and this morning it was at 55%. It was above freezing over night and the car is in a garage. Leaving the car plugged in has resulted in frequent but short charging sessions. I too suspect that it has to do with the updates to support the Tesla charging network since the notification that my car supports the new network coincides with the discharge issue.
Took it to the dealer to have it diagnosed and they told me this is normal. The service advisor called his "EQS guy" and that person said 4% drop in 12 hours is completely normal. This is my 4th EV and my first MB EV so please, those of you who've had your EQE/S for a few years, tell me just how crazy it sounds to expect that any vehicle would drain that much in such a short time when it's parked.
Took it to the dealer to have it diagnosed and they told me this is normal. The service advisor called his "EQS guy" and that person said 4% drop in 12 hours is completely normal. This is my 4th EV and my first MB EV so please, those of you who've had your EQE/S for a few years, tell me just how crazy it sounds to expect that any vehicle would drain that much in such a short time when it's parked.
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It sounds like we are having similar issues. I have a 2023 EQS 580 and I've been experiencing significant HVB drain over the past week or so. Last night I lost ~ 4% of the battery in 12 hours--went to bed with 59% and this morning it was at 55%. It was above freezing over night and the car is in a garage. Leaving the car plugged in has resulted in frequent but short charging sessions. I too suspect that it has to do with the updates to support the Tesla charging network since the notification that my car supports the new network coincides with the discharge issue.
Took it to the dealer to have it diagnosed and they told me this is normal. The service advisor called his "EQS guy" and that person said 4% drop in 12 hours is completely normal. This is my 4th EV and my first MB EV so please, those of you who've had your EQE/S for a few years, tell me just how crazy it sounds to expect that any vehicle would drain that much in such a short time when it's parked.
Took it to the dealer to have it diagnosed and they told me this is normal. The service advisor called his "EQS guy" and that person said 4% drop in 12 hours is completely normal. This is my 4th EV and my first MB EV so please, those of you who've had your EQE/S for a few years, tell me just how crazy it sounds to expect that any vehicle would drain that much in such a short time when it's parked.
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That's an insane drain rate. 9kWh in 24 hours is just insane. None of our EVs did this until recently. I'm waiting to see if our SUV does it now as well. In the meantime, I've disabled the J3400 adapter compatibility on the sedan to see if things improve. If not, it may be a bad 12V battery.
While at the dealer, I also mentioned the possibility of an issue with the 12v battery and the service advisor brushed me off stating, "That car has a ton of sensors in it--if there was a problem with the battery, it would tell you."
I have disabled the NACS adapter so that Tesla chargers aren't available in MBUX and I've disable both of our keys. I'll report back in the morning.
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Isn't it though? I asked the service advisor, "so if I leave this car at the airport for 2 weeks and it has 50% battery when I depart, when I return the car will be dead and you think that's acceptable?" He said "yes" and something about German engineers.
While at the dealer, I also mentioned the possibility of an issue with the 12v battery and the service advisor brushed me off stating, "That car has a ton of sensors in it--if there was a problem with the battery, it would tell you."
I have disabled the NACS adapter so that Tesla chargers aren't available in MBUX and I've disable both of our keys. I'll report back in the morning.
While at the dealer, I also mentioned the possibility of an issue with the 12v battery and the service advisor brushed me off stating, "That car has a ton of sensors in it--if there was a problem with the battery, it would tell you."
I have disabled the NACS adapter so that Tesla chargers aren't available in MBUX and I've disable both of our keys. I'll report back in the morning.
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EQE350 SUV 4MATIC
My EQE SUV has not been driven for 12 days and is in an underground garage at ~12C temperature,(outside below freezing). When I left the SOC was 62% and 209km. A day later the 12v battery showed partially charged. This condition did not change for 7 days, so I did a remote lock/unlock and saved a Departure time setting to get its attention. The next day the 12v battery showed as charged.
After all this the SOC is still 62% and the range has gone up slightly to 212km.
So losing anything like a few percent drops overnight indicates something abnormal, whether it be with an older car or a new car. Maybe a battery calibration should be performed (leave the car overnight with SOC below 20%), and then charge to 80% to rule out a calibration problem. If the issue continues take it back to the dealer. Do not take a "this is normal" explanation for their incompetence as it is not normal.
After all this the SOC is still 62% and the range has gone up slightly to 212km.
So losing anything like a few percent drops overnight indicates something abnormal, whether it be with an older car or a new car. Maybe a battery calibration should be performed (leave the car overnight with SOC below 20%), and then charge to 80% to rule out a calibration problem. If the issue continues take it back to the dealer. Do not take a "this is normal" explanation for their incompetence as it is not normal.
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From: Louisville, KY
2023 EQE350 4MATIC, 2023 EQE 350 4MATIC SUV, 2015 E250 BlueTEC 4MATIC, 1995 E300 Diesel
My EQE SUV has not been driven for 12 days and is in an underground garage at ~12C temperature,(outside below freezing). When I left the SOC was 62% and 209km. A day later the 12v battery showed partially charged. This condition did not change for 7 days, so I did a remote lock/unlock and saved a Departure time setting to get its attention. The next day the 12v battery showed as charged.
After all this the SOC is still 62% and the range has gone up slightly to 212km.
So losing anything like a few percent drops overnight indicates something abnormal, whether it be with an older car or a new car. Maybe a battery calibration should be performed (leave the car overnight with SOC below 20%), and then charge to 80% to rule out a calibration problem. If the issue continues take it back to the dealer. Do not take a "this is normal" explanation for their incompetence as it is not normal.
After all this the SOC is still 62% and the range has gone up slightly to 212km.
So losing anything like a few percent drops overnight indicates something abnormal, whether it be with an older car or a new car. Maybe a battery calibration should be performed (leave the car overnight with SOC below 20%), and then charge to 80% to rule out a calibration problem. If the issue continues take it back to the dealer. Do not take a "this is normal" explanation for their incompetence as it is not normal.
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2024 AMG EQE SUV , 2021 E63S Wagon - gone, 2018 E63S Sedan - gone
Yes, this essentially zero drain is what we're normally used to. No idea why it's changed. I do sometimes check the MB app, and notice that whenever it's seeing the increased drain, it's often reporting back to the MB app - the "last update" times change during the day/night. If it's *not* draining, then the "last update" time doesn't update at all since the last time the car was unlocked. Last night, the "last update" time didn't change for 12 hours, which is probably a good thing. Temperatures have warmed up, and I've disabled the J3400 adapter compatibility. I'm going to see how it goes overnight again, and then try to change just one variable to see if that changes anything.
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Apologies to bytemaster0--I feel like I've highjacked your thread--but since most of my journey has been documented here I'll close it out here.
I took my vehicle to another MB dealer and explained the situation. The service advisor called the technician who came up to the check-in counter to chat with me about what I've been experiencing. After hearing the details, the tech stated that while this isn't anything he'd encountered before, it sounded like an interesting problem, and that he would check for fault codes and perform a battery test. No fault codes were found but the battery failed the test. He replaced the battery under warranty and all has returned to normal. Navigation in the HUD and the Traffic Light View are behaving normally (can't recall if I had mentioned that they were not working correctly) and, most importantly, the SOC remained the same from the time the car was parked until I drove it this morning, a time period of ~20 hours.
Thank you to ScottC2 who suggested that my issue could be related to the 12v battery and to everyone who provided suggestions and feedback on their experiences with their vehicles. I'm really impressed with this community of EV owners.
I took my vehicle to another MB dealer and explained the situation. The service advisor called the technician who came up to the check-in counter to chat with me about what I've been experiencing. After hearing the details, the tech stated that while this isn't anything he'd encountered before, it sounded like an interesting problem, and that he would check for fault codes and perform a battery test. No fault codes were found but the battery failed the test. He replaced the battery under warranty and all has returned to normal. Navigation in the HUD and the Traffic Light View are behaving normally (can't recall if I had mentioned that they were not working correctly) and, most importantly, the SOC remained the same from the time the car was parked until I drove it this morning, a time period of ~20 hours.
Thank you to ScottC2 who suggested that my issue could be related to the 12v battery and to everyone who provided suggestions and feedback on their experiences with their vehicles. I'm really impressed with this community of EV owners.
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2023 EQE SUV 500 4Matic
Wow! Success!! Great that you found a dealer with some EQ knowledge and one that is inclined to care!
It's surprising a failed 12v battery doesn't log some fault codes, in my opinion!
It's surprising a failed 12v battery doesn't log some fault codes, in my opinion!
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The only indication that there was an issue with the 12v battery was if I happened to catch a non-normal status in the mobile app. It would state something like, "partially charged," but no notifications or errors.
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2023 EQE SUV 500 4Matic
Indeed. I would expect it to say something like "critical" rather than partially charged. But then, again, maybe the over-active charging by the HV battery was keeping it from reaching the "critical" level. At least it should indicate the battery is in poor health!
The 12v battery is so very important to so many systems in the EQ vehicles. Because of this, I'm astounded that the monitoring system for the so-called "health" of the 12v battery is not more sophisticated than it apparently is. :-)
The 12v battery is so very important to so many systems in the EQ vehicles. Because of this, I'm astounded that the monitoring system for the so-called "health" of the 12v battery is not more sophisticated than it apparently is. :-)
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2023 EQE350 4MATIC, 2023 EQE 350 4MATIC SUV, 2015 E250 BlueTEC 4MATIC, 1995 E300 Diesel
The car checks battery health by measuring internal resistance. However, this is just part of the story, as you can have capacity failure without resistance buildup. Rare, but I've seen it happen. I'm going to explain it to them in terms of AA batteries. Every 24 hours, my car is expending almost 500 AA batteries-worth of energy. That's gotta shock them into doing something, lol. My dealer is great, but I'll nudge them toward the 12V. Great work, congrats on solving your issue, hijack of thread much appreciated!
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The car checks battery health by measuring internal resistance. However, this is just part of the story, as you can have capacity failure without resistance buildup. Rare, but I've seen it happen. I'm going to explain it to them in terms of AA batteries. Every 24 hours, my car is expending almost 500 AA batteries-worth of energy. That's gotta shock them into doing something, lol. My dealer is great, but I'll nudge them toward the 12V. Great work, congrats on solving your issue, hijack of thread much appreciated!
