Originally Posted by Diesel Benz

Could you try to find a link to that article. I did not find it from Motortrend or Car & Driver.

Any battery loses charge over time even if completely disconnected from the outside world. For lithium batteries this is insignificant. What sort of figures did the article talk about? 1% a day, week, month, year? Makes a difference!

I'm not sure if the high voltage battery control unit actually did some periodic checks. I would assume more like hard wired leak monitoring but in any case, nothing that would cause noticeable battery drain on an EV with a relatively huge battery.

The 12 V battery has a lot of continuous load. Nothing like the starter on an ICE car but significant compared to the total capacity. The alarm system is on when parked (of the order of 40 mA power consumption), the remote access modem is on, keyless go is active etc. All these are a significant power drain if e.g. the car was not driven for a month.

The 2% loss for the high voltage battery that is being discussed, must have some other explanation than normal periodic tasks or battery internal leak. Could be timed (unintentional) cabin pre-conditioning, the car detecting the key and triggering heat seating. Perhaps battery cooling after charging session although this should not be needed when charging at home with low current (cooling or heating).

Originally Posted by tbirdvet

Could not find the exact article but in the 2-23 issue of Motortrend they tested a Rivian RIT on an overnight trip and found the charge loss was about 2% over each night. Rivian claimed it is because an EV requires certain systems to be kept alive so when the vehicle is started up there are minimal delays for all to function. The person that tested the unit almost diid not make it back home.

Originally Posted by LasVegas_89135

I've owned a Tesla Model S since 2017. The Tesla forums call this "vampire drain". My overnight drain has been constantly 2% per night in any weather (I live in Las Vegas, mild winters, very hot summers)

Originally Posted by LasVegas_89135

I've owned a Tesla Model S since 2017. The Tesla forums call this "vampire drain". My overnight drain has been constantly 2% per night in any weather (I live in Las Vegas, mild winters, very hot summers)

Originally Posted by Diesel Benz

Mercedes recommends a 25 - 30 % SOC for the battery if the car was left unused for a long time. Then charge if SOC drops down to 15%.

Originally Posted by Diesel Benz

At 2% drop per night, one would need to charge the car after a week or less!

Originally Posted by Diesel Benz

Odd if Tesla people have not figured out what this battery drain is and how to avoid it.

Originally Posted by finlayson

Actually, Mercedes' recommendation (from the EQS SUV owner's manual; I assume that the same is true for the EQS sedan) is to keep the SOC between 30-50% if you're leaving the car unused for a long period of time. And to charge if the SOC drops below 20%

Originally Posted by Diesel Benz

Mercedes appears to have many different recommendations. The figures I mentioned were from my manual (the quick reference for my car).

Originally Posted by finlayson

And the figures I mentioned (to leave the SOC between 30-50% if parked for a long time, and to charge if the SOC gets below 20%) were from the 2023 EQS SUV manual (which is also online at https://www.mbusa.com/content/dam/mb...s%20Manual.pdf ). Are there really different manuals for the EQS that give such different numbers?

Originally Posted by Tjdehya

Its the same for the sedan. It is exactly as you stated.
You should avoid leaving your batter below 20% for long periods just as much as you should avoid leaving your battery at 100% for long periods.
Based on my understanding of battery technology the optimum SOC to minimize degradation is at or near 50% of the charge capacity. So even though MB recommends 30-50%, I wouldn't panic if you were stuck having to store the vehicle at a slightly higher percentage.

Originally Posted by Diesel Benz

If it is considered safe to have 80% SOC in normal use, something higher than 50% cannot be critical for long term parking. I'm no battery expert but lower than 50% is most often referred to the safest figure. Since extreme lows are also unsafe, I guess it is a bit of a matter of opinion how much room for internal discharge is needed. EQS with insignificant drain should be fine with less than 50% initial charge. Finlayson, my figures were from my car, not the EQS but if you read all Mercedes manuals including different translations I'm sure you will find other figures in addition to those of mine and yours. Go figure if different figures are for different battery technology variants or just artist's personal view. The idea is simple, avoid very high SOC and avoid very low SOC too. 30 to 50% is not really different from 25 to 30% in this context (my personal interpretation).

Originally Posted by c4004matic

MB recommends 50%.

Originally Posted by VinceF

Related question: I'm going away for a week, is it OK to leave the car plugged in at home on my Level 2? I always did so with my Tesla, is it the same for Mercedes?

Originally Posted by ScottC2

Interesting thread!Later this year, I will take delivery of an EQE SUV I ordered in December. In 2024, I will be on an extended and complicated trip that will entail leaving the car in a safe garage or parking facility in Greece for 5-6 months.
This thread has awakened me to the fact that I need to adequately prepare for this. But how?? Perhaps I can find a very sophisticated storage situation, complete with somebody that I can count on to charge the car periodically?? Or, could it be that I could plug the car in and monitor and control the charging remotely? Does anyone have any other thoughts?

Originally Posted by finlayson

If the EQE is like the EQS, then you should be able to leave it for 5-6 months without having to charge it at all during that time. I doubt you'd see any more than 10% loss (probably a lot less) during that time. I'd recommend starting with a battery level around 50%.

Originally Posted by VinceF

Related question: I'm going away for a week, is it OK to leave the car plugged in at home on my Level 2? I always did so with my Tesla, is it the same for Mercedes?

Originally Posted by finlayson

It's probably OK, but the owner's manual recommends against doing this. Specifically: "If leaving the vehicle idle for lengthy periods, park up the vehicle with a high-voltage battery state of charge between 30% and 50%. Do not keep the high-voltage battery continuously connected to power supply equipment.".

Based on my own experience (leaving my EQS SUV unused for two months, two separate times), you'll see almost no drop in charge if you leave your car unused for a week.

Originally Posted by LastOne

Contrary to the owner's manual about not leaving the car plugged in for an extended period, would it not be reasonable to leave the car plugged in BUT set the preferred condition of charge to 50%? It seems the system should not continue to charge beyond this point.

ps. I am a prospective EV owner and does some research.

Originally Posted by c4004matic

The car, unlike other brands, has essentially no parasitic losses.

Originally Posted by finlayson

And of course, during your trip, you can monitor the charge level remotely using the "MercedesMe Connect" app, assuming that your car is within reach of a cellular data network. (The charge level gets updated in the app about once each day.)

Originally Posted by Diesel Benz

the 12 V battery is not charged unless ignition is on or the HV battery is in active charging state.