Steve446
Dusty Crophopper, M3 LR 2021 Midnight Silver
I agree, with you. So maybe I wasn't totally clear - I was talking about real world range and not rated range.
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Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health
- Thread starter KK_RedM3
- Start date
bkp_duke
Well-Known Member
Sigh. Yes, the BMS does heat the battery while parked, to ensure that the battery temp will no drop below critical and cause damage.
Yes, the BMS does heat the battery when drive if needed (through the superbottle or octovalve to redirect heat as needed - and you do point out that is from the motors).
How many Tesla have you cracked open the battery to? How many have you rooted? /me raises hand to both of these questions.
Do you have any evidence that it actually does?
I'm pretty sure it does not do any thermal management when parked, at least that isn't triggered by the user for preconditioning. (It would be pointless as there isn't enough energy in the battery to maintain the temperature for a long period of time, for example if it is parked at an airport and not plugged in.)
bkp_duke
Well-Known Member
Back in the two salvaged 2013 Model S's that I had and worked on, this was observed behavior on SW 8 through 10. I haven't rooted one since I got rid of those cars. Could the behavior have changed? Yes. But at the time that is what I observed, was that the cars would periodically come out of sleep, check the bat temp, and cycle on.
I have logs from the BMS that show;
-Ambient temp.
-Cell temp
-SOC
-When battery heating is on or not
-when the car is sleeping
-and any other data present in the BMS.
I also see these live on a on board screen.
(In my M3P I used Scan myvtesla all time, 2.5 years and the screen mounted in front of the steering wheel.)
On the Plaid I have the same tablet loose in the center console.
I also have the possibility to se when the car sleeps or is awake.
When a Tesla sleeps, the main battery is disconnected and can not deliver energy to any heating or anything at all.
I regularly leave the car for one week at the time outside at work. I live in a bery cold climate so the battery temp soon reaches -10 to -20C or so. If I leave the car for one week, about 1-2% less SOC is left, thats just about the same number as the 1% during summer.
Also, seeing the car sleepihg al day except for a short while charging the LV battery without the cell temp rising guarantess tgat the battery was not heated.
I do not need to crack them open, as I havexsystems logging all data I need.
For the M3P 2021 i had from dec 2020 until june 2023 and the MSP from that day and still have, I have defentive knowledge of both these cars heat and not heat the battery.
I do not know about the old ones.
bkp_duke
Well-Known Member
Interesting. Well the older of the 2 cars I had was in the VIN 4000 range, and I have to tell you that car truly felt like I was driving a prototype car. Great at the time, but I would not tolerate it anymore.
I have not seen my car actively heat or the cool the battery once it goes to sleep (2022 and 2018 Model 3). Tracking via power usage at the Wall Connector.
My 2014 Chevy Volt DID do this though. I would go into the 100 F/38 C garage and the AC compressor would be spinning and it would be cooling the battery.
My 2014 Chevy Volt DID do this though. I would go into the 100 F/38 C garage and the AC compressor would be spinning and it would be cooling the battery.
This is about a week, just grabbed a period int the logs.
The three purple vertical lines is the only time the battery heating was on during this week.
The car is inside the garage at ~10C during nights but driven daily.
All three was triggered by either just starting the AC/clima/heater in the app, or scheduled departure. Actually the car was left outside to see how the car heats the battery, if it does like the Model 3 (it does).
In this time line there is also a drive where the car was outside for hours to cool the battery to "cold temp" (reached about -6C) and then driven directly without any preconditioning or scheduled departure etc. That drive did not trigger the battery heating at all.
(a lot of data deselected to make the table easier to read.)
Here is a day with a scheduled departure. Charge inside the garage at 0330, and driven to my wifes work. Cel temp steady declining until -5.5C The scheduled departured first started warming the battery and then heated the cabin to be ready 15 minutes before the set time. Parked in the garage at about 18:00 and then a new charge 0330, and a drive about 1200 the next day.
The three purple vertical lines is the only time the battery heating was on during this week.
The car is inside the garage at ~10C during nights but driven daily.
All three was triggered by either just starting the AC/clima/heater in the app, or scheduled departure. Actually the car was left outside to see how the car heats the battery, if it does like the Model 3 (it does).
In this time line there is also a drive where the car was outside for hours to cool the battery to "cold temp" (reached about -6C) and then driven directly without any preconditioning or scheduled departure etc. That drive did not trigger the battery heating at all.
(a lot of data deselected to make the table easier to read.)
Here is a day with a scheduled departure. Charge inside the garage at 0330, and driven to my wifes work. Cel temp steady declining until -5.5C The scheduled departured first started warming the battery and then heated the cabin to be ready 15 minutes before the set time. Parked in the garage at about 18:00 and then a new charge 0330, and a drive about 1200 the next day.
Talking to a Tesla "battery" tech, after I had raised a service support he mentioned that about 4 years old and older, all appear to flatten at 15% degradation and company-wide that's where it levels. And that my car was doing a bit better than others at similar age.
He wouldn't provide however degradation value nor battery capacity.
Using the car service mode, I got a value of 9% a few months ago
45000km
Manufacturing date: July 2019, Delivery date September 10th 2019
I typically plug in, SoC is typically set to 70%, lately I've set it to 80.
*when* the car is plugged, it is set to charge at 1PM on a 11kW 3-phase wall charger.
I do use the free chargers around commercial center a lot.
used to be parked in the driveway, uncover.
I've now built a carport, and so the car has been under cover for the past 3 months.
nope.
Outside temperature.
It hasn't been particularly hot these days, quite the opposite. Though, it's Melbourne Australia, could by 40C at 2pm and 18C at 5PM, you never know
@AAKEE
As we head into hot summers in Australia - often temperatures are 30-40⁰C during the day and 20⁰C night. I wonder if I should reduce max SoC or changing the charging session time. I am now able to charge at one workplace for free with 2.3kW AC
This was my routine during autumn when the max temps were 20⁰C and down to 10⁰C overnight (average):
My garage is not insulated and has some delay in temperature equalisation between inside and outside
Tuesday SoC 40% charge to 70% (free workplace charge)
Wednesday SoC drops by 10% (not at free charging workplace)
Thursday SoC drops by 10% (not at free charging workplace)
Friday SoC drops by 10% (not at free charging workplace)
Saturday SoC 40% charge to 50% (at home during day - charge at home with solar)
Sunday SoC 40% charge to 50% (free workplace charge)
Monday SoC 40% charge to 50% (free workplace charge)
What do you consider is "high" ambient temperature?
Would you do any different?
As we head into hot summers in Australia - often temperatures are 30-40⁰C during the day and 20⁰C night. I wonder if I should reduce max SoC or changing the charging session time. I am now able to charge at one workplace for free with 2.3kW AC
This was my routine during autumn when the max temps were 20⁰C and down to 10⁰C overnight (average):
My garage is not insulated and has some delay in temperature equalisation between inside and outside
Tuesday SoC 40% charge to 70% (free workplace charge)
Wednesday SoC drops by 10% (not at free charging workplace)
Thursday SoC drops by 10% (not at free charging workplace)
Friday SoC drops by 10% (not at free charging workplace)
Saturday SoC 40% charge to 50% (at home during day - charge at home with solar)
Sunday SoC 40% charge to 50% (free workplace charge)
Monday SoC 40% charge to 50% (free workplace charge)
What do you consider is "high" ambient temperature?
Would you do any different?
I reckoned the end of the day SOC would be about 10% lower then the charging level, which I swet to 75%, as you have used both(45K km during 4.5years)
Annual average temp is 15.6C in Melbourne. Average cell temp set to 25C, I guess you guys have more sun heating the car than I have with 0C as the average annual temp.
I would not think that you could only have 9% degradation from the 77.8kWh "Full Pck When new" (I do not know what number the service mode use as the original capacity).
As battery degradation like calendar and cyclic aging is rather predictable, there are not really any battery lotteries to win.
Annual average temp is 15.6C in Melbourne. Average cell temp set to 25C, I guess you guys have more sun heating the car than I have with 0C as the average annual temp.
I would not think that you could only have 9% degradation from the 77.8kWh "Full Pck When new" (I do not know what number the service mode use as the original capacity).
As battery degradation like calendar and cyclic aging is rather predictable, there are not really any battery lotteries to win.
i don't know either.
Tessie uses 75.2kWh as original battery size, and shows 8.9% which was close to the Tesla service mode. I'm now happy to think that my battery is sitting at 71.5kWh, may not be correct, but it makes me feel better
When it comes to free charging and the opportunity to charge for free and to balance the saved money to the possibly increased or reduced degradation, I am not the guy to ask. I have a fixed electrical rate, quite cheap so I do not think anything about that. I have free supercharging but I still charge full before leaving home for a longer trip, even if supercharging would save me a few buck. Just for convinience, not to save the battery either.@AAKEE
As we head into hot summers in Australia - often temperatures are 30-40⁰C during the day and 20⁰C night. I wonder if I should reduce max SoC or changing the charging session time. I am now able to charge at one workplace for free with 2.3kW AC
Hard to tell.
First the basics, if you like to reduce the degradation (otherwise you would not ask, I guess):
-Do not charge more then needed until the next charge.
-Charge often, it reduces the cycles size which is good, also reduces the need on the point above.
-Charge late, to reduce the average SOC, this will be extra effective when you need to charge above 55% (as above 55% increases the calendar aging).
You have 40% as the low point, and do not need a 40% reserve range? I would try to only charge to 55% on tuesday. Would put you at 15% end of the friday before the saturday solar charge. 50-40 or 30% has about the same calendar aging, and the batterty is actually also happier below that, so the only thing to look out of in terms of low SOC is your range anxiety (and to nod be stranded somewhere).
Anything above freezing
No, but there is not really a sharp limit. And you mostly can not do anything about it. The warmer it gets the higher the calendar aging, but in a smooth increase with increasing temperature. So no limit.With SOC it is different. SOC at or below 55% (for Panasonic NCA, I do not know I you did get the LG cells yet, in that case 55% is 60% instead).
You can se for a specific SOC that the calendar aging is progressively higher due to temperature, but no specific limit.
For different SOC's you can see that 55% "costs" about 2.75-3% at 25C temp for the first 10 months and that 70-100% will "cost" about the double amount.
That curve is generalized by only one test point at 55 and one at 60% but no point between. The research did find the exact point that is about 57% SOC, to stay below. Due to the buffer 55% displayed is 57% true SOC so we can use 55% or below.
Tessie is more often wrong than right about capacity. Its a 2019 LR, right? Then we know that the starting value shoulf be 77.8kWh, at least.i don't know either.
Tessie uses 75.2kWh as original battery size, and shows 8.9% which was close to the Tesla service mode. I'm now happy to think that my battery is sitting at 71.5kWh, may not be correct, but it makes me feel better
Tessie calculates the full capacity so it really should say 77.8kWh inside the tessie meter (you can change this).
On the other hand, the value Tessie calculates as the capacity today must be 68.5kWh then. (8.9% less from 75.2). Seems on pair with the most probable capacity if you ask me.
I know no one wants "high degradation", but I do not think there is any help if I do not tell what I think. Sooner or later you probably find it out anyway.
And that number, 12.5% I calculated is not a fail or a lost battery lottery. Inmstead it is the reality and about what to expect.
I know some EPA tests got more than 77.8kWh out of the battery. If the battery mostly started about 1kWh higher than 77.8 than you probably would have about 1kWh more today. But Tessie seem to calculate the current capacity quite well (they suck on finding the starting value, but the capacity mostly is on pair with the BMS...when the BMS is on track).
Your car has quite low ODO/miles., but that doesnt help much as the absolut most part of the degradation the first 5-8 years comes from calendar aging.
I am very interrested in seeing the long term development for your car, or more to know when the BMS adjusts back. (As i do not expect the new capacity value to be correct.) I hope you can keep us posted?
Do not need 40% reserve range. Happy to go to 30% as this is what Jeff Dahn recommends
No range anxiety - can go to 20% as well to keep sentry active
If Tesla allowed minimum charge limit of 40% I would use that
This is a ten day log. Only one battery heating came from scheduled departure (the first shown in the upper pic). The second was me using Plaid mode + dragstrip more to test a short battery heating session (we where talking battery heating power in another forum, if a Plaid could use all three engines fpr heating the battery). Last one was preconditioning for a supercharging session.
There was several cabin heating sessions durring these days (the lower part is the same data but the cabin preconditioning is also showed).
The day of the third november the cell temp decreased during the day, even when the cabin heating was left on to keep the temperature when being in stores etc. No battery heating at that time either.
My M3P and my MSP only heats the battery when:
- Preconditioning before supercharging
- Charging DC
- Charging AC, if the car is ouside and cell temp close to freezing and then up to 3-4C for slow charging with the Plaid, and to 7C with the M3P.
- Scheduled departure, when the cell temp is about 3-5C or below. When heating the battery it just heats to about 5C.
- Starting the cabin heat, for example with the app, and the rules are just like above for scheduled.
All other times the battery is not heated.
This is 21 jan 2023 at 5pm. The car has ben parked for several days at work and the cell temp was -12.5C no battery heating after the car was charged to 55% two days before. The SOC was virtually the same, seen on Scan my Tesla
The lower part of the picture shows how most days look, the car sleeps with the HV battery disconnected (no battery heating possible), and wakes up briefly to charge the LV battery one or two times a day.
Upper picture shows the start of the charging (to be able to drive 240km in -20- -25C. The battery heating heats the battery as it can not be charged below freezing. Tesla doesnt charge below +3C.
AlanSubie4Life
Efficiency Obsessed Member
467km/511km * 77.8kWh = 71.1kWh.
Story checks out!
Original constant is ~152Wh/km but that only gets you to 499km at 76kWh. Actual starting point was 511km, 317.5mi (shown as 499km/500km/310mi), 77.8kWh.
Line on the energy screen is ~155Wh/km (aka 152Wh/km mentioned above, since that is how Tesla rolls; 3Wh/km high).
Story checks out!
Original constant is ~152Wh/km but that only gets you to 499km at 76kWh. Actual starting point was 511km, 317.5mi (shown as 499km/500km/310mi), 77.8kWh.
Line on the energy screen is ~155Wh/km (aka 152Wh/km mentioned above, since that is how Tesla rolls; 3Wh/km high).
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