Your car has been parked for 2 months? In this case MB must have changed their 12 V charging strategy (for a good reason). Wonder if anyone seen any bulletins about the change.

My hybrid still loses Mercedes Me connectivity after being parked for a long time (because of low 12 V battery). My SW has been updated more than half a year ago, at least MBUX has had an update since then, perhaps the battery control units too.

 

Yes. My car was parked from October 25th 2022 to January 3rd 2023. During that time, my (high-voltage) battery charge dropped from 37% to 33%. It has also been parked from February 1st 2023 to now. During that time (so far), my (high-voltage) battery charge dropped from 41% to 40%. In each case (according to the "MercedesMe Connect" app), the 12V battery was occasionally recharged during the time that the car was parked.

 

I of course believe what you are saying but this does not match with the experience many EQS owners have had. Search for 12 V battery issues gives a huge number of hits. A battery management SW change could explain the difference to your experience but it would be nice if someone with the knowledge could confirm this or could provide some other explanation for the different behaviour many others have faced.

On an ICE car the starter battery had no chance to survive several months. Assume some 100 mA idle power consumption and a 90 Ah battery would be almost flat in a month. Perhaps MB first assumed this would be enough for EVs and didn't bother to make use of the HV battery.

 

That may be true for old batteries. But when I was in the military I never came back home from a deployment to a dead battery. I just parked my car, went out for 6-8 months, arrived home and the cars would start right up. Over winter, over summer, it didn't matter. Your "no chance" statement is very hyperbolic.
Most of the cars that had 12V issues happened because the car was left on while window tinting, exterior wraps, or just plain weird anomalies. I don't think any were related to long term parking.

 

This is nothing about old or new batteries. If you read my comment enough to respond, you should have commented on the figures I gave. Old or new battery, the total capacity has a limit and I assumed a brand new battery.

Which car did you leave parked for 8 months? Probably some with no electronics. We have machines that sleep 8 months between seasons but they have no consumers active when parked.

An older Mercedes consumes typically 40 mA current for the remote door locks (Keyless Go a bit more) + the alarm. The current generation MB cars must consume at least 100 mA because of the Mercedes Me connectivity plus a more advanced alarm system (I have not seen factory figures, please add if you know). Now calculate the the battery capacity needed for this drain (ignore any internal battery leak or capacity loss from aging). 100 mA times 180 days times 24 hours equals 432 Ah. A 432 Ah battery would not be enough because you cannot start the car with a flat battery.

Why did the EQS cars get flat battery when they were left on while windows were tinted? You just agreed with the other comment that the 12 V battery is charged from the high voltage battery even when parked. Certainly it is charged when the car is on!

EDIT: the reference to older Mercedes cars fixed, my memory failed a bit. The idle current on a 2010 or so car would be typically 40 mA on a car with an alarm.

 

Update: I have about 2700 miles on the car now. I have had no significant loss. I think battery capacity is sensitive. Battery conditioning and Cabin conditioning can draw 1 or 2% from time to time within the first few miles.

 

Just curious as to where they came up with 20-50% SOC for long term storage. What is the downside of say leaving the car at 70% SOC?

 

I lost 2% last night too. charged from 19% and reach 80% stoped at 4am. my phone shows 80% in the morning when I check it. but when I started the car at 9am it shows 78%.. don't know why but might be due to software update? brand new car I just picked up yesterday afternoon.

 

The downside is obviously reduced battery life. The difficult to answer question is "how much?". Perhaps some experts on battery chemistry onboard. I doubt it would be anything significant at 70%.

 

Are you sure you do not have any unintentional cabin preconditioning scheduled for 9 AM or so? Could be one time or every Sunday or every morning etc.

 

I routinely let my SOC drop to 20-25% and then charge my car to 80%. That usually lasts me about two weeks before I need to charge again. So if I charged it to 80% instead of 50% and this time let the car sit for 4 months I can’t see how I would be really harming the batteries life by leaving it at 80% rather than driving it till it reached 50% and then storing it for a few months. I’m only talking about doing this once a year.

 

Lithium battery degrades, whether you use it or not.
All these recommendations (charge to 80% etc) are to reduce the rate of degradation.

So storing it at 80% is not "harming" the battery; it's just that at the end of 4 months, the battery charged to 40% would retain more capacity than that at 80%.
Lithium battery stored at 100% charge at 25 degree celsius would see its capacity reduced to 80% after 1 year.
While one stored at 40% charge at 25 degree celsius would have 96% capacity after 1 year.
80% charge would be something in between.
And for 4 months, we are talking a few percentage here. It's not a big deal, but since it is something which can be done easily without much effort - charging to 40-50% instead of 80%, why not?

 

The question is not about "how many times per year you park the car at a high SOC" but how many days (per year) the battery has high SOC. According to google battery chemistry works in the way that a higher SOC degrades the battery more over time. MB does not give figures and I did not google for any exact numbers. The difference in degradation may be marginal or it may be significant (whatever that means in absolute terms).

Since you only charge the battery up to 80%, I interpret you agreeing with the MB advice and the fact that a higher SOC reduces battery life (to some extent). A lower than 80% figure seems safer than 80% but during normal use, restricting SOC to 50% may not be practical. We have to accept a compromise between battery health and range etc. during normal use while for long term parking a lower SOC would be quite practical.

Again, I'm sure we have battery engineers onboard to clarify the topic if it can be explained in a way an ordinary driver would understand.

 

I do charge my car to 80% max as per recommended guidelines from Mercedes and people in this forum. I thought that the charging process above 80% is what leads to battery degradation, not the absolute state of charge. If it’s the higher state of charge that degrades the batteries over time, then yes, I can understand to only charge it to 50% before leaving it for long periods of time. The car was charged to 80% as per my routine and when I left the car in my winter home it still had 75% SOC. I planned on storing the car in my air conditioned garage in south Florida for the summer. In the future do you feel it would have been better to let it sit there at 50% SOC in the future?
It just seems a bit confusing to me that you can’t utilize the full extent of the battery and therefore get better range because it hurts the battery in the long run.

 

I dont think so. but it does feel weird that when I plug, on the app it said pause and said there is no profile. I click few things and somehow it starts to charge.
it works a bit different than my eqs suv 1st charge. I guess I will continue monitor it.

 

I would try to follow the instructions from the manual, taking into account what forum members say here (not me), this is what I do.

I doubt your battery is hurt much more than theoretically if you once leave it parked longer at 80% SOC. 100% charging is "acceptable" just before a long trip to avoid 100% SOC for a long period of time.

I think you are right about charging hurting batteries but not only from 80% to 100% SOC. After all, batteries generally are rated to survive some number of charging cycles. Since charging is a must, the manual cannot ask us to avoid that for battery health.

Charging and parking at high ambient temperatures is bad (is not good), you are safe again with your air-conditioned garage.

 

As I mentioned long ago in this thread, I will be storing my car long-term for about 5 months in Greece during the summer/fall of this year. From reading on this thread and elsewhere, I have concluded:

1) I should leave the car with the High Voltage battery charged to 50%
2) The 12v battery is critical to many systems while the car is off/at rest, including remote monitoring
3) Some have experienced conclusively that the 12v battery is occasionally and automatically charged by the High Voltage battery.
4) Others have experienced that their 12v battery was NOT charged occasionally and automatically by the High Voltage battery.
5) I want to be 100% certain I don't have a surprise waiting for me when I retrieve my car at the end of the storage period.
6) To avoid the aforementioned surprise, I would be wise to deploy a 12v trickle charger.
7) To connect the aforementioned trickle charger, I need to open the hood (customer-forbidden area).

My questions for this august body:
1) Has anyone here stored their EQ* with a 12v trickle charger? If yes, do you have any photos or description of where I can connect the charger - preferably on an EQE SUV?
2) Does it have to be a special type of 12v trickle charger? Can anyone recommend a specific make/model?
2) Any tips for opening the hood on the EQE SUV?

 

I have been having problems with the 12v charging while my car sits for several days in my garage. I leave it with 60-80% SOC and the 12v battery will not fully charge. I have left the car for 2 weeks at a time and occasionally the battery shows critical low red warning. I put a NOCO trickle charger on it overnight to fully charged and a couple of days later it goes down to partially charged even though I drive the car. Truthfully I think there is something wrong with my 12v battery rather than the system. But when I use the car now the battery only reads partially charged. I was too chicken to leave the trickle charger on for a long period. It’s easy to use. Under the front hood are the two connection for the battery. You just have to use something to prop open the hood so it doesn’t smash against the battery terminals as you charge.

 

Thank you for the reply. I assume you have an EQS.
I agree with you that it sounds like it could be an issue with the battery. While I've only had my EQE SUV for just shy of 3 months, I have very rarely seen it on status "partially charged". It's almost always "charged". The one time I can recall seeing it partially charged was when it was at a hand-wash carwash for about 45 minutes and I could tell that doors were open here and there for some time. I have NEVER seen it say "partially charged" after driving.

 

I have a 23 EQS 580 sedan. It was dropped off at Baltimore VPC in July of 22 and delivered to my dealer in December of 22 despite it being a custom order from me. Not sure if sitting at the VPC for 5 months unused has anything to do with it but I’m going to take my car in for service soon because I was told I have a few modules to update and free back seat pillows.

 

I would not hesitate to put a trickle charger on for long term storage. The hood is easy to open, you just have to remove the plastic device covering the standard MB latch (one screw). The battery posts are in direcdt view on the passenger side of the car near the firewall. BTW, when I take my car in for service/window tinting, etc, I reach to the overhead panel and turn off the interior light switch, which is the most right of the switches. A red led will light to let you know it is off. This saves lots of 12V current if the service center leaves the doors open. Has worked well for me so far.

 

Plugging in the High Voltage battery will lead to the car charging the low voltage battery. So trickle charging is not necessary if you have access to an EV charger.

 

You would think so. I have charged my car twice in the last 5 days and driven every day and my 12 v battery still reports as partially charged. When I get a chance I am going to make a service appt to check it out.

 

I believe you need a new 12 volt battery. I had this problem about 10 months ago and the dealer replaced the battery free of charge.

 

Going in for service on the 30th. Will update what they say about battery.