Charge loss while parked
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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).
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).
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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.
The only thing I can think of is pre-heating the battery for a quick start at extreme cold in order to gain full power from the start. This however consumes so much energy that the battery cannot be heated all the time to be ready for a trip any time. Perhaps they had programmed pre-heating, something that is not essential to start a trip? One time heating of battery and interior just before a planned start of a trip and observed the battery loss after this event, perhaps not even being aware of the set departure time...
EDIT: I found the article. Either an extremely poor EV design or something else wrong with the car. Do they have the drive train controlled by a Windows computer? Even there, should be aware of different sleep modes. It takes a few second for the Mercedes MBUX to wake up and much less for the necessary computers that are needed to get going. Amazing if the manufacturer has no better explanation and no proper solution.
Last edited by Diesel Benz; Feb 9, 2023 at 08:42 AM.
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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)
Last edited by LasVegas_89135; Feb 9, 2023 at 06:08 PM.
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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%. At 2% drop per night, one would need to charge the car after a week or less!
I assume we are talking about 2 percent unit SOC drops per night, not 2% off from the current SOC. If the car is consuming some power, it would consume the same kWh figure at any battery SOC.
Odd if Tesla people have not figured out what this battery drain is and how to avoid it.
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This thread started with the 2% SOC loss over night on an EQS but other than that, Mercedes cars do not seem to have any noticeable high voltage battery charge loss when parked.
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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?
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.
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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.
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.
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).
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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).
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Sorry but no. MB recommends "30 to 50%" for the EQS (from the US manual), not 50%. MB recommends 25 to 30 for my car!
Again, sorry about continuing on the topic as I don't think any of the figures make any measurable difference but I cannot leave it after all figures have been clearly explained and then an inaccurate figure arrives.
EDIT: for anyone it may interest, a link to our (confusing) on-line manual page:
https://moba.i.mercedes-benz.com/bai...921-en-GB.html
Again, sorry about continuing on the topic as I don't think any of the figures make any measurable difference but I cannot leave it after all figures have been clearly explained and then an inaccurate figure arrives.
EDIT: for anyone it may interest, a link to our (confusing) on-line manual page:
https://moba.i.mercedes-benz.com/bai...921-en-GB.html
Last edited by Diesel Benz; Feb 11, 2023 at 11:13 AM.
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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?
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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?
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?
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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.
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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?
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?
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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.)
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Agree.
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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.
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.
ps. I am a prospective EV owner and does some research.
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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.
ps. I am a prospective EV owner and does some research.
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The 2017 Tesla Model S that I just traded in would loose 2% per day, everyday (Tesla owners refer to this as Vampire Lose). But my wife's 2021 Volvo XC40 Recharge has no lose while sitting unplugged in my garage.
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You are only considering the HV battery. It is the 12 V battery that dies first and remote connectivity via Mercedes Me at the same time. The point is that all idle consumption is on the 12 V battery when the car is parked and the 12 V battery is not charged unless ignition is on or the HV battery is in active charging state.
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My reason for thinking this is that - each day while my car has been idle (for almost 2 months now) - I check (remotely, using the "MercedesMe Connect" app) both the % charge of the high-voltage battery, and the state of the 12V battery. (I check the latter using the "Service" button in the app; it shows the status of the 12V battery, along with the brake fluid and washer fluid.) Most days, the app says that the 12V battery is fully charged. Occasionally, however, it says that the 12V battery is only partially-charged. This continues for a few days, but then it will report that the 12V battery is fully charged once again. At that time, I often find that the high-voltage battery's charge percentage has dropped by 1%. So, it seems that the 12V battery will never be fully depleted, as long as the high-voltage battery is charged to a reasonable level.
