Charge as often as possible (minimize average DoD) and keep the charge limit set as low as you can get away with and charge as late as possible before you depart by using the Scheduled Departure feature (minimize average SoC).
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Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health
- Thread starter KK_RedM3
- Start date
Can you give me a better example? Currently I’m doing like 50 or 60% to 80% should I let it go lower to like 20/30% and charge it to 50% or so instead?
It's better to use a lower charge limit (30-50% is better than 60-80%) and smaller depth of discharge is better than a larger depth of discharge (40-50% every day is better than 30-50% every other day). I set my charge limit at 50% and plug in every night. I use about 10-15% of the battery per day, so it goes down to around 35-40% before being charged up to 50%. I set the Scheduled Departure for just before I leave in the morning so it sits at the lower SoC for most of the night.
I will typically charge to 100% every 3-4 months to let the BMU recalibrate the top end reading but again, I only do this before I drive at least 30-50 miles and I set Scheduled Departure for about an hour before I leave so it doesn't sit at 100% for very long.
Don't be afraid to use the upper 50% of your battery if you need to, but to keep degradation low, try to only use it when you need to.
I stay fairly in tune with this subject (and thanks to @AAKEE and others for the empirical data!), but question for the group...
This might be lost in the mysteries of the BMS, but do we have any idea whether we get good OCV reads if we plug in immediately when arriving at home but charging is scheduled to start, for instance, 6 hours later? For example, I get home at 6pm and I have charging scheduled to start at midnight (or 2am, or 4am, whatever). Is the system 'asleep enough' to get OCV readings with scheduled charging enabled? Does the MCU (and other stuff) stay on equivalent to leaving Sentry on when scheduled charging is enabled? Does it matter? ... anybody really know?
This might be lost in the mysteries of the BMS, but do we have any idea whether we get good OCV reads if we plug in immediately when arriving at home but charging is scheduled to start, for instance, 6 hours later? For example, I get home at 6pm and I have charging scheduled to start at midnight (or 2am, or 4am, whatever). Is the system 'asleep enough' to get OCV readings with scheduled charging enabled? Does the MCU (and other stuff) stay on equivalent to leaving Sentry on when scheduled charging is enabled? Does it matter? ... anybody really know?
The car will fully sleep when plugged in, so no worries about when you plug in.
Great thanks for this! However, since i don't charge at home i don't have the luxury of charging it whenever I need it. I do have it at work. But i do WFH and hybrid every other week. Is it safe to say i can do supercharging 30-50% or maybe 20 - 50%. Also as for 100% charge i have never done that. Should maybe do that now and then do it every couple months?
Also what is the best way to measure the degradation of the battery? I keep it at the % rather than miles. I kinda have a somewhat of a range anxiety but it' getting better!!
My Sentry mode is always on. So my car never "FULLY" sleeps. but i have no choice cause i need to know what is going on all the time. Especially in my building and at work...And it's amazing how many people walk past the car and look inside it or when the light flashes and they get super scared! LOL. It's like KNIGHT RIDER!
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We had a discussion recently about cell temperstures in the battery and after looking into this I’d say that the battery is averaging quite much above the ambient for a day with charging/ driving/ standing in the sun.
When cold the car use the heat to keep the driver happy, and this keeps the battery cold(heatingthe cabin cools the battery) but when not cold the battery temp goes up instrad of ”down”.
I have a average battery temp since september thats 12.25C. September tonow is the cold period with heating at my place.
Today I left the car in the sun at work (not that high elevation up here, and it was not a clear sky all day, but partly sun shine). The ambient was about 10C when driving to work and 15C leaving work. Average outside temp 14C. Highest temp was 17-18C,(19C is probably the sensor being heated from direct sun light.)
The average cell temp is 25.6C despite not many drives. 2 x 46 km to/from work and some short drive in the home town, to the supermarket etc.
This is > 10C above the average ambient temp. Not worried for my car but the statement from someone here about the cell temp being only a few or five degrees above ambient do not seem probable.
Living in a hot climate probably sky rocket the average cell temp, specially when the car stands inthe sun.
When cold the car use the heat to keep the driver happy, and this keeps the battery cold(heatingthe cabin cools the battery) but when not cold the battery temp goes up instrad of ”down”.
I have a average battery temp since september thats 12.25C. September tonow is the cold period with heating at my place.
Today I left the car in the sun at work (not that high elevation up here, and it was not a clear sky all day, but partly sun shine). The ambient was about 10C when driving to work and 15C leaving work. Average outside temp 14C. Highest temp was 17-18C,(19C is probably the sensor being heated from direct sun light.)
The average cell temp is 25.6C despite not many drives. 2 x 46 km to/from work and some short drive in the home town, to the supermarket etc.
This is > 10C above the average ambient temp. Not worried for my car but the statement from someone here about the cell temp being only a few or five degrees above ambient do not seem probable.
Living in a hot climate probably sky rocket the average cell temp, specially when the car stands inthe sun.
I wonder what the temperature of the road surface is? If it's dark and been in sun for a while it could be hotter than the air?
Steve446
Dusty Crophopper, M3 LR 2021 Midnight Silver
Yes , I think you have a point. Particularly to deal with average temperatures rather than "instantaneous" values. dealing with the integral of a moving temperature and the impact on battery temperature would be complicated. Your situation, and others like you in the same geographical area, are maybe the downside case. I would like to think my location is possibly a middle average location (Dept. Loire Atlantique , Western France). Those of you in places like Cadiz in Andalusia or other places further afield in the USA or Australia might be the upside case. It would be interesting to see battery temperature data from others in these down, mid and upside cases. I guess there will be a seasonal influence too. For information my average ambient and battery temperatures are:
March: 12.4°C / 18.4°C
April: 14°C / 17.6 °C
May: 17.6°C / 25.6°C (to current date).
Quoted temperatures are at the time of measurement.
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AlanSubie4Life
Efficiency Obsessed Member
2019 - 240rmi, 52.5kWh
2020 - 250rmi, 52.5kWh
2021 (NCA) - 263rmi, 53.5kWh
These numbers all include the buffer, and represent the degradation thresholds.
These are the numbers that matter for capacity loss determination.
It's a two-year-old car, so 47kWh, 11% capacity loss is perfectly normal in some climates in typical use cases.
There really isn't anything wrong with these habits, and for a vehicle at this age, it probably doesn't make much sense to worry about minimizing capacity loss (since it slows down now), but it's best to charge to as low as possible, preferably lower than 50%, and recharge as frequently as possible, as close to when you drive again as possible. But again, I agree, nothing really wrong...just charge the car in a way that doesn't make it a giant PITA.
I don't think there's a lot of evidence that significant amount of range can be recovered. Of course there are instances where the BMS has a bad estimate but much of the time it makes no difference to charge the battery, discharge it, let it sleep, and then charge it up again - because the estimate is often excellent. My main point is that it doesn't make sense to get people's hopes up especially if the observed capacity loss is perfectly normal for the age of the vehicle. Could it actually be only 8% loss? Sure.
Just look at the rated range at 100%. It's best to only look at the value when actually charged to 100%, or at least to 90% and then use the extrapolation feature in the app - values of this extrapolation at low state of charge can be off by 100 miles due to rounding error on the extrapolation. So for example, if you have 350 rated miles @100%, you've lost ~2.2% capacity from your 2022 starting point of 358 miles (which is ~79kWh including the buffer, I believe - though don't quote me on this, since someone has to provide the data from the car Energy Screen for a 2022 for us to know for sure - it could be, for example, 81kWh - they got 82kWh out of the car on the EPA test - and they have some latitude on this choice, which is why I said don't quote me on it until the data is presented (I haven't been asking people to post it but maybe someone already did)).
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@AAKEE thank you for all the input and data sharing! Very interesting, and you have convinced me that low SoC over time will promote the maximum battery preservation.
That being said, I have a question: how are you setting the charge below 50%? In the app, I cannot slide it below 50%. Do you just set departure for later than you intend to drive away?
That being said, I have a question: how are you setting the charge below 50%? In the app, I cannot slide it below 50%. Do you just set departure for later than you intend to drive away?
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Blacktes24
Member
Just got a new 2022 M3P Monday and the default setting is 90%. I thought i had read the batteries were updated to where it is ok to go to 100% now? Thanks for any input!
Thats only the Rear wheel drive model 3, not the AWD or performance (so no, thats not correct for your car).
Blacktes24
Member
Ah ok. Thats disappointing as performance starts dropping quite a bit from 85-60%. I need to research more I guess on how I should charge. Is 90% all the time ok?
Blacktes24
Member
i was up to 98% and pulled it down after reading this thread to 90%. I assume it won't hurt much as they say only use 100% if u are planning a long trip?
AlanSubie4Life
Efficiency Obsessed Member
From immediately above:
MASTER THREAD: Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health
This will not give you the best performance. If you just do whatever, and enjoy the performance, expect to lose about 10% capacity over the first 2-3 years. Maybe a bit more, maybe a bit less. Following a more conservative strategy may help a bit but will be more annoying.
You cant set it below 50%.
There is ways have the charging stop before 50%, like setting the charge to commence late enough to not reach 50% before driving away.
Having a lot of ”not completed charge sessions” might affect the BMS battery capacity estimation so it may be not recommended.
There isnt really a reason to aim below 50% anyway. First thing is, if charging is set to be finished not long before the trip, the calendar aging will be small. You can charge to 100% if driving away without delay, and the calendar aging will not be high if the SOC is driven down to low SOC again.
50% is below the “step” (for calendar aging) around 55-60% for NCA so it is also quite low even if the car is left over time with 50% SOC.
If you drive very little, just a few percent each day or so, the degradation is actually cut in half by changing from charge to above 60% to 55% or below.
If you still wich to reduce degradation further, you need to either not charge daily or get the charging to not have the time to finish.
Also see my post before this.
If you reduce the time from charging to driving by charging *late* and drive the SOC down to low values you will not have any measurable increased calendar aging.
This chart is only refering to *time at high SOC* You can go to 100% and down to below (for example) 50% during the drive and then having below 50% during the night and still have degradation according to this chart at the low SOC value.
If you need 80% you can carge to 80% just before the drive without cost in this graph.
Charging to higher SOC most often means bigger cycles (otherwise most people do not need to charge to higher SOC). Bigger cycles means more cyclic aging. But this still is only a fraction of calendar aging.
For you ( @Blacktes24 ) if you “need” the power and drive only a little daily ( i.e do not drive the SOC down) you need to choose between more power or lower calendar aging. A active choice knowing the facts behind is a good thing.
There is nothing wrong with choosing power
The warmer the battery is, the more power until the max output of the engines. A just finished charging session means hotter battery and more power, so the SOC where the power starts reducing is lower.
At the same batt temperature the maximum battery power is around 85% SOC.
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