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Discussion Starter · #1 ·
After one successful session powering a tyre air compressor using the cigarette socket in the boot, I locked the car. Returned 15 mins later and unlocked the car, pressed the start button, no screens 馃槼

I was able to use the compressor again and the Aircon came on. I drove the car around our cul de sac, all worked ok but no screens.

Pressed the MercedesMe button and was connected, they sent a request to the RAC for a patrol, MB support rang back to say they could not send a MB Technician today, so booked one in for tomorrow.

I bet it gets towed to the dealer tomorrow 馃檭
 

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The funny thing is that only once when I started the car the right-hand screen didn鈥檛 come on. Fortunately the HUD worked so I could see the speed. Got home ok and next day everything was fine. It hasn鈥檛 happened since (yet).
 

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Maybe check app to see if 12v battery low, though I expect Mercedes Me already checked that and it might even use a small bit of charge. Driving for longer as MikeP likely did or charging the bigger battery may help (I am guessing although it may only apply to other models like EQS) but if Mercedes sending help tomorrow then they are not requiring that you need to troubleshoot plus maybe there is liability issues if they asked you drive without speedometer
 

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After one successful session powering a tyre air compressor using the cigarette socket in the boot, I locked the car. Returned 15 mins later and unlocked the car, pressed the start button, no screens 馃槼

I was able to use the compressor again and the Aircon came on. I drove the car around our cul de sac, all worked ok but no screens.

Pressed the MercedesMe button and was connected, they sent a request to the RAC for a patrol, MB support rang back to say they could not send a MB Technician today, so booked one in for tomorrow.

I bet it gets towed to the dealer tomorrow 馃檭
Ours had the MBUX screen blank out after parallel parking. After it reached the stopping point the steering wheel rotated 30 degrees violently left and right about 6 times. After leaving it off for a few minutes it was working again.
 

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Discussion Starter · #6 ·
Maybe check app to see if 12v battery low, though I expect Mercedes Me already checked that and it might even use a small bit of charge. Driving for longer as MikeP likely did or charging the bigger battery may help (I am guessing although it may only apply to other models like EQS) but if Mercedes sending help tomorrow then they are not requiring that you need to troubleshoot plus maybe there is liability issues if they asked you drive without speedometer
12v battery is showing partially charged, so maybe that鈥檚 the problem

Question: why does the 12v battery get discharged, when there is a huge power supply available in the main batteries?

MB Me didn鈥檛 ask me to drive, I did that before ringing them and when I did ring they made it clear it鈥檚 against the law!
 

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I am not sure if the higher voltage main battery can charge the 12V or not, especially if not driving, however charging the main battery can also topup the 12V battery so if you plugin to charge the car main battery it will also give 12V an opportunity to charge back to normal level, as dBC proved-


Maybe ask Mercedes if this is OK to do first though in case there is other problems.

I understand when a customer activates their Mercedes Me account, they can receive SMS or app alerts if either the 12V battery or high-voltage battery becomes too low, advising to recharge the high-voltage battery, because when an EQC is put on charge, or likely any EQ vehicle, it also internally charges the 12V battery so a separate charger is not required (though there are connection points so 12 V separate charging also seems to be possible).

As you likely have not received a critical alert of 12 V too low, the blank screen may be only partly related to the 12 V drain as I wonder if non-critical 12 V drain would cause blank screen on it's own unless maybe car is trying to prevent the critical too-low 12V state? Maybe it is a software bug like seems happened for DTech so hopefully we all get an update at some point for this, and hopefully not a hardware problem
 

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Discussion Starter · #8 ·
MB Technician opened the door and the screens came to life 馃檮 he plugged in diagnostic computer and noticed a software connection failure to the screen. dated the previous afternoon, checked software version ( old version) and passed report to my local dealer and suggested we book it in for a software update (cntl/ alt/ delete comes to mind馃槀). Booked in next Tuesday, up to 25 hours apparently. He said if screens go blank again lock up car for at least 30 mins so that the car closes down completely.
 

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MB Technician opened the door and the screens came to life 馃檮 he plugged in diagnostic computer and noticed a software connection failure to the screen. dated the previous afternoon, checked software version ( old version) and passed report to my local dealer and suggested we book it in for a software update (cntl/ alt/ delete comes to mind馃槀). Booked in next Tuesday, up to 25 hours apparently. He said if screens go blank again lock up car for at least 30 mins so that the car closes down completely.
Thanks for letting us know, we really are getting into the unplug and restart or the soft boot territory these days which is a bit worrying!
Hyundai/Kia have dreadful problems with their 12v batteries which fail quite early and seem to cause all sorts of issues inc stopping the car from even starting lots of discussions as to why on SpeakEV forum. Some people recommend trickle charging the 12v battery reguarly yet Mercedes tell us to only have the 12v battery system charged at a qualified workshop馃 is it because of the way the car looks after it by charging it from the HV battery as suggested above I wonder, is that common to all electric vehicles or just some? As a Mercedes鈥 driver who is paying for a premium product I expect premium design and service so I am hoping the 12v issue will not crop up in the Mercedes鈥 EQ design. i have noted they use small batteries which are classified as deep cycle whereas some replacements sold via non Mercedes鈥 sources are merely normal batteries you would find in ICE cars馃
Finally why should we all be having to go to dealers for software updates why on earth can they not get these organised as OTA?
 

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Discussion Starter · #10 ·
Thanks for letting us know, we really are getting into the unplug and restart or the soft boot territory these days which is a bit worrying!鈥..,
Yea I agree 馃檮

鈥..Finally why should we all be having to go to dealers for software updates why on earth can they not get these organised as OTA?
maybe it鈥檚 a bit like Microsoft and Apple updates of days gone by where the whole system file structure was replaced by the update, rather than ad today, where only updated components are updated. I wonder if MB updates are like the former, I guess a 25 hour update cycle provides some clues 馃槀
 

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Some people recommend trickle charging the 12v battery reguarly yet Mercedes tell us to only have the 12v battery system charged at a qualified workshop?? is it because of the way the car looks after it by charging it from the HV battery as suggested above I wonder, is that common to all electric vehicles or just some?
I wonder about that too. Tesla Model 3 and Toyota bz4x both seem to allow typical jumpstart procedure of connecting positive and negative, and I did read of an EQS owner who said a mobile Mercedes tech seemed to do the same for his car even though EQS manual says to contact a workshop. I guess either Mercedes is very cautious about who should touch the electrics or else it is necessary to meticulously check for other issues specific to EQ before attaching the jumpstart cables, something not all jumpstarters , even so-called professionals, may be capable of. An older car I had (not Mercedes) got toasted power inverter and other electronics when the new owner tried to jumpstart it at an airport. I wouldn't be surprised if they got the positive and negative mixed up or other error though. It would have been cheaper to buy a replacement car than fix the electronics (13 year old car) though they eventually got it working before selling by buying parts direct from scrapyards
 

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Yea I agree 馃檮



maybe it鈥檚 a bit like Microsoft and Apple updates of days gone by where the whole system file structure was replaced by the update, rather than ad today, where only updated components are updated. I wonder if MB updates are like the former, I guess a 25 hour update cycle provides some clues 馃槀
That is going to be fun then as more and more EQ鈥檚 are sold all queuing up to be connected for 25hr updates馃檮 garages are going to need to improve their own infrastructure too and be connected to very high speed fibre surely馃oh what fun we can all anticipate馃槈
 

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I wonder about that too. Tesla Model 3 and Toyota bz4x both seem to allow typical jumpstart procedure of connecting positive and negative, and I did read of an EQS owner who said a mobile Mercedes tech seemed to do the same for his car even though EQS manual says to contact a workshop. I guess either Mercedes is very cautious about who should touch the electrics or else it is necessary to meticulously check for other issues specific to EQ before attaching the jumpstart cables, something not all jumpstarters , even so-called professionals, may be capable of. An older car I had (not Mercedes) got toasted power inverter and other electronics when the new owner tried to jumpstart it at an airport. I wouldn't be surprised if they got the positive and negative mixed up or other error though. It would have been cheaper to buy a replacement car than fix the electronics (13 year old car) though they eventually got it working before selling by buying parts direct from scrapyards
Mercedes鈥 are very safety concious which may well be the only reason they take the line they do and the EQS and EQE do not even allow access under the bonnet to the owner of course. Frankly it is probably a good thing as someone somewhere will kill themselves tinkering with the systems they do not understand.
Time will tell if they have a better system for the 12v battery or not from some of the other manufactuers. I do tend to think the price one pays for a Mercedes鈥 is reflected in better quality components and mechanical design etc like v4 of say ABS is installed in a Mercedes鈥 whereas a cheaper car like say a Dacia is still using v1 and certainly you can see that in the Dacia whose engines are old Renault models. Fingers crossed馃槈
 

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I am not sure if the higher voltage main battery can charge the 12V or not, especially if not driving,
There's a DC/DC that charges the 12V battery. It takes 400V input from the big battery and operates whenever the engine is started (i.e. "READY"). It also operates whenever the big battery is being charged. And finally, if you've left the car unused for an extended period... about 2 or 3 weeks in my case, and it notices the 12V battery getting critically low, it operates.

There's a picture of it in this post.

"Partially charged" is a fairly normal state for the 12V battery, especially if you haven't used the car in the last day or two.
 

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Here you go one on sale via a Mercedes鈥 dealership. I have had a poke around my car but I cannot totally see the battery but from what I could make out it looks smaller than the one in the e class which was quite a brute of a thing. From what I can read up these batteries where used as the auxiliary batteries of earlier ICE cars running all the 12v stuff like headlights etc leaving the main battery to cope with the start up. However my 2015 c class did not have an auxiliary battery as such but rather some sort of capacitor condenser system which failed in a lot of cases after 2 yrs which mine did. The 2018 e class must have had a similar system but Mercedes鈥 had sorted it as that was still fine when the car was sold at 3yrs old e appeared to be no complaints of the forums I visited for that car.
Hyundai seem to have a big big problem with their 12v battery also the Renault zoe from what I see. I have never seen anything other than a fully charged result on Mercedes鈥 me for my 12v battery but will monitor it when the car has not been charged and left standing for a few days.

 

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Here you go one on sale via a Mercedes鈥 dealership. I have had a poke around my car but I cannot totally see the battery but from what I could make out it looks smaller than the one in the e class which was quite a brute of a thing. From what I can read up these batteries where used as the auxiliary batteries of earlier ICE cars running all the 12v stuff like headlights etc leaving the main battery to cope with the start up. However my 2015 c class did not have an auxiliary battery as such but rather some sort of capacitor condenser system which failed in a lot of cases after 2 yrs which mine did. The 2018 e class must have had a similar system but Mercedes鈥 had sorted it as that was still fine when the car was sold at 3yrs old e appeared to be no complaints of the forums I visited for that car.
Hyundai seem to have a big big problem with their 12v battery also the Renault zoe from what I see. I have never seen anything other than a fully charged result on Mercedes鈥 me for my 12v battery but will monitor it when the car has not been charged and left standing for a few days.

I don鈥檛 know how your car manages with a 12ah battery my motorcycle has a 14ah battery!!
My EQA has a 64ah battery and because I have a dashcam which runs when parked I fitted a battery monitor, it has shown the battery dropping to 40% or less on numerous occasion, probably because I do short journeys and I have a 22kw charge point which don鈥檛 give enough time to charge the 12volt battery. This means I have to charge the 12volt once a month or so. I have found the Mercedes me app has only once shown a warning to charge the 12volt battery and it doesn鈥檛 give any advance warning that the battery is getting low, insisting it is fully charged right until it鈥檚 less than 40%.
 

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I don鈥檛 know how your car manages with a 12ah battery my motorcycle has a 14ah battery!!
My EQA has a 64ah battery and because I have a dashcam which runs when parked I fitted a battery monitor, it has shown the battery dropping to 40% or less on numerous occasion, probably because I do short journeys and I have a 22kw charge point which don鈥檛 give enough time to charge the 12volt battery. This means I have to charge the 12volt once a month or so. I have found the Mercedes me app has only once shown a warning to charge the 12volt battery and it doesn鈥檛 give any advance warning that the battery is getting low, insisting it is fully charged right until it鈥檚 less than 40%.
It def is the battery for my car as I did a no plate test. And on the same site the same battery comes up for the EQA鈥︹︹f course these batteries do not have to suffer the power drain of turning over an ICE engine they are only there to run items when the main lit-ion battery is not in circuit so to speak. As I understand it this battery鈥檚 job is to run things like lights and ancillaries when the high voltage battery is not connected ie when the car is not switched on to ready mode.
On one of the EQ screens you can see a breakdown of the consumption of the car between driving, heating cooling and other consumption. I assume the other is all the ancillary stuff running at the time and the recharge of the 12v battery and it can be as high as 8% but also lower. As an aside yesterday it was 20deg outside the same temp as the interior setting and the heating/cooling system was showing 0% consumption.
I take your point re the app and the level who knows what measurement they have programmed it for but it certainly is different to my e class (a 2018 e220d estate) which often showed partially charged and nagged me during our lockdowns.
On your issue of needing to charge your battery reguarly I have seen many other drivers do that in the Hyundai, Kia鈥檚 and Renault marks particuarly. Frankly I would not be a happy bunny if I had to faff around like that with what for me was a 90k car (I genuinely could buy a house for that money!).
I do use my car for lots of short journeys and it may not be used for 2 or 3 days in a row with only a 8km return trip before it stands again and so far no issues over 9mths how that progresses we shall see.
I wonder if the dashcam itself is what is draining the battery if it is running all the time one would not expect such a small item to do so but I am not an automotive electrics expert just a punter who has an enquiring mind on how these things work馃槈I look forward to the day when I can finally have a dashcam built into the car and the Tesla system does appeal about the only thing Tesla offer that does appeal actually馃槈
I too was surprised at the size of the battery but clearly Mercedes鈥 have a lot of experince of these deep cycle battery's used to run the ancillaries and it has to be said many were surprised there even was a 12v battery in an electric car when you have the large lith-ion one used to power it. But it does seem when these batteries start failing they do cause all sorts of difficulties and it seems to me we will have 2 main intial reactions when an electric car starts giving funny messages or will not power up, switch off and switch on again ie ctrl alt delete or replace the 12v battery the cry all so familier on many of of our other electrical consumables馃ぃ
 

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It def is the battery for my car as I did a no plate test. And on the same site the same battery comes up for the EQA鈥︹︹f course these batteries do not have to suffer the power drain of turning over an ICE engine they are only there to run items when the main lit-ion battery is not in circuit so to speak. As I understand it this battery鈥檚 job is to run things like lights and ancillaries when the high voltage battery is not connected ie when the car is not switched on to ready mode.
On one of the EQ screens you can see a breakdown of the consumption of the car between driving, heating cooling and other consumption. I assume the other is all the ancillary stuff running at the time and the recharge of the 12v battery and it can be as high as 8% but also lower. As an aside yesterday it was 20deg outside the same temp as the interior setting and the heating/cooling system was showing 0% consumption.
I take your point re the app and the level who knows what measurement they have programmed it for but it certainly is different to my e class (a 2018 e220d estate) which often showed partially charged and nagged me during our lockdowns.
On your issue of needing to charge your battery reguarly I have seen many other drivers do that in the Hyundai, Kia鈥檚 and Renault marks particuarly. Frankly I would not be a happy bunny if I had to faff around like that with what for me was a 90k car (I genuinely could buy a house for that money!).
I do use my car for lots of short journeys and it may not be used for 2 or 3 days in a row with only a 8km return trip before it stands again and so far no issues over 9mths how that progresses we shall see.
I wonder if the dashcam itself is what is draining the battery if it is running all the time one would not expect such a small item to do so but I am not an automotive electrics expert just a punter who has an enquiring mind on how these things work馃槈I look forward to the day when I can finally have a dashcam built into the car and the Tesla system does appeal about the only thing Tesla offer that does appeal actually馃槈
I too was surprised at the size of the battery but clearly Mercedes鈥 have a lot of experince of these deep cycle battery's used to run the ancillaries and it has to be said many were surprised there even was a 12v battery in an electric car when you have the large lith-ion one used to power it. But it does seem when these batteries start failing they do cause all sorts of difficulties and it seems to me we will have 2 main intial reactions when an electric car starts giving funny messages or will not power up, switch off and switch on again ie ctrl alt delete or replace the 12v battery the cry all so familier on many of of our other electrical consumables馃ぃ
My EQA had the 65ah 12volt battery from new. I have considered disconnecting the permanent feed wire to the dashcam and just having it start with the car for a while to see what effect it has. I haven鈥檛 had any problems with the car not doing everything it should when the 12volt battery was at a low state of charge, except for losing connection with the app, so I don鈥檛 know how low it needs to go to cause faults with the car, my reason for charging it regularly is more to prevent any sulphation shortening of the life of the battery and also I really don鈥檛 want to find the critical level of charge by experiencing some of the horror stories related by the owners of Korean cars or by becoming stranded!!
 

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Discussion Starter · #20 ·
Just picked up the car from the main dealer, they replaced the screens and updated software - good now 馃馃徎馃馃徎馃馃徎
They said low 12v battery was not the cause of the failure. On the plus side they also cleaned the car inside and out - saved md a job this week! 馃槀
 
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