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What should my ideal charge percentage be?

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Why do you say balancing is a myth? Every two or three months my 90D will lose a couple of miles that is easily recalibrated by driving it down to 10-20% and then charging up to 93-100%. This was all very well documented in wk057's research. It seems to be more a software algorithm thing in the BMS than a battery issue.

Balancing does take place, of course that is not a myth. I have been able to monitor my battery closely with TM-Spy for over a year now and was able to see how far the cells drift apart under what condition.

Partially charging does not cause the cells to drift apart. Partially charging causes the errors of the battery gauge to add up and it becomes less accurate. This is something Tesla officially stated in an email. The algorithm just gets less accurate and estimates on the lower end to be save. It looks like you are loosing range. Discharging to near 0% and charging to full (or almost full) recalibrated the gauge algorithm and you get the lost range back. Tesla explained it this way, but some people, for some unknown reason, prefer to say the cells get out of balance and then charging to 100 would re-balance them.

Looking at how much and when the modules in my car drift apart or not showed me that they actually do not drift apart much at all. Even when I partially charged for weeks. Jason noticed that balancing starts when 93% battery level is reach, but then it runs independent of state of charge or weather the car is plugged in or not. The bleeding resistors are very small so it could take many hours, maybe even days.
 
Balancing does take place, of course that is not a myth. I have been able to monitor my battery closely with TM-Spy for over a year now and was able to see how far the cells drift apart under what condition.

Partially charging does not cause the cells to drift apart. Partially charging causes the errors of the battery gauge to add up and it becomes less accurate. This is something Tesla officially stated in an email. The algorithm just gets less accurate and estimates on the lower end to be save. It looks like you are loosing range. Discharging to near 0% and charging to full (or almost full) recalibrated the gauge algorithm and you get the lost range back. Tesla explained it this way, but some people, for some unknown reason, prefer to say the cells get out of balance and then charging to 100 would re-balance them.

Looking at how much and when the modules in my car drift apart or not showed me that they actually do not drift apart much at all. Even when I partially charged for weeks. Jason noticed that balancing starts when 93% battery level is reach, but then it runs independent of state of charge or weather the car is plugged in or not. The bleeding resistors are very small so it could take many hours, maybe even days.
Yep, based on lots of experience I've learned you don't really need to get all the way down to zero miles or 0%. I usually will go to 10-20% or ~30-60 miles. As I recall, Jason explained calibration and balancing as two different things. Is that the way you remember his explanation?
 
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Yep, based on lots of experience I've learned you don't really need to get all the way down to zero miles or 0%. I usually will go to 10-20% or ~30-60 miles. As I recall, Jason explained calibration and balancing as two different things. Is that the way you remember his explanation?

I have to find that email from Tesla again, but in simple words it said that both at near empty or near full, the capacity can be determined pretty accurately. In the middle, it's more difficult and they have to keep track of how much energy went in and out but it's limited in how good that works. If you charge and discharge partially over some time, the errors just add up. Letting the battery go down low and/or charging near full will recalibrate.

Based on watching the battery for about a year now balancing never becomes as much of an issue that it would cause any range loss.
 
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This is very similar to Dahl's research. Again, the key seems to be avoiding high states of charge, at high temperatures, for long periods of time. Remember also that Tesla's batteries are thermally managed and almost never get completely discharged. Charging to 80% and discharging down to 20% wears a battery negligibly, according to this and Dahl. It does not answer the "keeping it plugged in all the time" question.

BTW, I have an 85D that is just over a year old with almost 19,000 miles. I have only done 2 range charges. When the car was new, top mileage was 275, 5 more than rated. I have not done a range charge in a while, but if I divide the charged miles by the charged percentage (e.g. 192 miles at 70%) I always get right around 274, and my SOC is usually around 30-50%. Every two weeks I cycle from 80% to 10% or so when I spend the weekend away. I will bet that when I do my range charge shortly my wear will be <1%.
 
Why do you say balancing is a myth? Every two or three months my 90D will lose a couple of miles that is easily recalibrated by driving it down to 10-20% and then charging up to 93-100%. This was all very well documented in wk057's research. It seems to be more a software algorithm thing in the BMS than a battery issue.

Here's why I'm skeptical:

a) I've never been able to "recover" lost miles on my 85 by doing this;

b) Some have reported that when they received a "loaner" pack (i.e. for contactor repairs) that the miles will immediately be different with the loaner pack, then return to where they were before when they get their own pack back. No running down and charging up to calibrate necessary.
 
Here's why I'm skeptical:

a) I've never been able to "recover" lost miles on my 85 by doing this;

b) Some have reported that when they received a "loaner" pack (i.e. for contactor repairs) that the miles will immediately be different with the loaner pack, then return to where they were before when they get their own pack back. No running down and charging up to calibrate necessary.
As I recall, you have a particularly long commute--and some times it's a cold commute. This probably keeps the algorithm close to correct. It's not surprising that you don't see any change.
 
I'm trying to do more videos rather than writing. I think I'm better at that :)
Your writing is the best.
Good videos too!
I'm watching your Regeneration Test right now. And you are doing it with a rear-wheel drive only car-- with dual motors the regeneration should be even better.
Nice style, good filming. You should be on TV. And what a great-looking car at 3:00.
 
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Isn't this backwards? More heat is generated at lower SOC while driving, because as voltage drops, more amps are needed to provide a given power. Or are you saying that there is something about the battery chemistry that it is more tolerant of heat at a lower SOC?
Yes. The battery degradation is lower when SOC is low at high temp than high SOC. In really cold weather the difference is much lower between low and high SOC. Yes, driving increases temp regardless of SOC. Degradation accelerates with higher SOC and higher temp, but keeping low SOC in high temp will not be worse than keeping high SOC in cold weather :)
 
Yes. The battery degradation is lower when SOC is low at high temp than high SOC. In really cold weather the difference is much lower between low and high SOC. Yes, driving increases temp regardless of SOC. Degradation accelerates with higher SOC and higher temp, but keeping low SOC in high temp will not be worse than keeping high SOC in cold weather :)
Which is why Teslas are liquid cooled. Ambient temperature makes little if any difference because of that.
 
Which is why Teslas are liquid cooled. Ambient temperature makes little if any difference because of that.
I have to disagree. No coolingmeasures takes place below 30C. Keeping same SOC at 30C vs 5C will make a huge dufference in lifespan. SOC of 40% at 30C might double the batterylife compared to 90% SOC. If outside temp is 20C+ I would really keep my SOC at 50% for long time storage. If you have a fast chargeroption I would l
Keep it around 50% all the time. The NCA-deg curve shows extreme differences in lifespan a temps well below 20C between long and high SOC.
 
I have to disagree. No coolingmeasures takes place below 30C. Keeping same SOC at 30C vs 5C will make a huge dufference in lifespan.

There is a good reason for that, though. Cold temperatures are good for the life of a battery, but it's bad while using the battery. Driving and charging a cold battery would result in bad performance and stress on the battery which would also reduce it's life. That's why Tesla actually warms up the battery to 30 C all the time when in use.
 
There is a good reason for that, though. Cold temperatures are good for the life of a battery, but it's bad while using the battery. Driving and charging a cold battery would result in bad performance and stress on the battery which would also reduce it's life. That's why Tesla actually warms up the battery to 30 C all the time when in use.
There is no stress on battery while cold. Tesla makes sure of that when limiting power and regen. It does not affect lifespan, but due to overall lower temp lifespan increases. Active heating is done up to about 8C, about 30kW regen. Passive cooling starts above 30C. Tesla considers anything between 8-30C as optimal drivingtemp. Since TMS is a high performance car, heating battery just above powerlimit while getting half regen is a decent choice.
 
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There is no stress on battery while cold. Tesla makes sure of that when limiting power and regen. It does not affect lifespan, but due to overall lower temp lifespan increases. Active heating is done up to about 8C, about 30kW regen. Passive cooling starts above 30C. Tesla considers anything between 8-30C as optimal drivingtemp. Since TMS is a high performance car, heating battery just above powerlimit while getting half regen is a decent choice.

A cold battery will get damaged when charged or discharged too fast and that's exactly why the power is limited when the battery is cold. It's there to protect it. As with everything regarding the battery, it's not perfectly fine at a certain temperature and then really bad at a different temperature. At 0 Celsius (or lower), charging the battery is stopped because of the damaging effect. It's not like at 5 degrees it's all fine. It's OK but it still causes more stress on the battery than when it's at 35 C. Same with discharge. The colder the battery the more damaging the use thus Tesla limits the output power. As temperature goes up it allows you to use more and more power. If the battery was kept at 8 C all times it would not be good and that's exactly why Tesla warms it up to about 30 or 40 C (when range mode is on).

If 8 degree, as you say, would be considered fine, Tesla would not make an effort to heat the battery. I've been watching the temperature of the battery for about a year now and have seen what the car does in all kinds of different situations. It will always warm the battery to 30. If 8 C was OK it would stop pumping warm coolant into the battery and let the battery stay at 8. But it does not. It will warm up the coolant going into the battery all the way up to 30 or 40 C.
 
A cold battery will get damaged when charged or discharged too fast and that's exactly why the power is limited when the battery is cold. It's there to protect it. As with everything regarding the battery, it's not perfectly fine at a certain temperature and then really bad at a different temperature. At 0 Celsius (or lower), charging the battery is stopped because of the damaging effect. It's not like at 5 degrees it's all fine. It's OK but it still causes more stress on the battery than when it's at 35 C. Same with discharge. The colder the battery the more damaging the use thus Tesla limits the output power. As temperature goes up it allows you to use more and more power. If the battery was kept at 8 C all times it would not be good and that's exactly why Tesla warms it up to about 30 or 40 C (when range mode is on).

If 8 degree, as you say, would be considered fine, Tesla would not make an effort to heat the battery. I've been watching the temperature of the battery for about a year now and have seen what the car does in all kinds of different situations. It will always warm the battery to 30. If 8 C was OK it would stop pumping warm coolant into the battery and let the battery stay at 8. But it does not. It will warm up the coolant going into the battery all the way up to 30 or 40 C.
Uhm. You seriously just said what I said. 8C battery temp allows for 30 kW regen. According to canbus batteryheater turns off at 8C, regen is then about 30kW. The battery heats itself slowly no matter what the outside temp is. Its due to the heat from using it. Noticed that most batteries gets hot from using them? Excactly the same with every battery. They are not 100% efficient. All wasted energy creates heat. You probably know this aswell as I and we talk passed each other :)

There is no way Tesla will allow the battery to be damaged in cold weather, hence the regen/power limits which I referred to earlier.
 
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If you saw the pict I uploaded it says 30C kicks in the passive cooling measures. It does not heat the battery and uses cooling fluid to help that. Cooling fluid is cooled by fans. With very high temp heat-pump-ac actively cools batteries :)

The things I just said is not info from me, its info from canbus via connecting through ODB2, its what the vechile says its doing ;)
 
If you seriously mean that its bad for the battery operating below 8C which is Teslas temptarget (can differ slightly between firmwares), it would be a disaster selling it here in Norway. In winter we have many days with below -10C. Some over -20C. Only way to remove regenlimit on those days is if you have 32A 400V 22kW charger from dualcharger or using superchargers. Its very rare to drive without regenlimit from October to April where I live. The battery rarely gets to 15-20C where regenlimit dissapears. You seriously mean that even wirt Teslas power/regen-limits the battery is hurting? Seen the Leaf survey-study where the lose dots extremely slow in northern america and northern europe? Texas on the other hand... Leaf also limits regen in cold weather. I have driven a lot of Leaf aswell and they behave the same in cold weather :)
 
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