Battery Calibration 0-100% - does it make sense?

[AlbertEgger]

Hello,

Some people are claiming, that once a year I should drive my battery to 0% and then charge it to 100% with the idea, that the BMS knows what capacity the battery has and to balance the cells.

Others say, driving to 0% is not healthy for the battery and should be avoided , it’s long it’s not badly needed. The BMS calibrates itself automatically and the battery is also balanced all the time when needed.

So, what is true? Should drive my battery once a year down to 0% and charge it to 100%? Or is this not needed at all?

 

[DCGOO]

Hello,

Some people are claiming, that once a year I should drive my battery to 0% and then charge it to 100% with the idea, that the BMS knows what capacity the battery has and to balance the cells.
Others say, driving to 0% is not healthy for the battery and should be avoided , it’s long it’s not badly needed. The BMS calibrates itself automatically and the battery is also balanced all the time when needed.
So, what is true? Should drive my battery once a year down to 0% and charge it to 100%? Or is this not needed at all?

It is never a good idea to get down to absolute 0, after all, you really do not want to call a tow truck. But the low single digits is fine. There is also nothing magical about doing this annually. Personally I just use routine driving. If regular driving gets me very low, say to 15%, I might use that opportunity to take the car down to 5% or less. But it really isn't that big of a deal. It doesn't really do anything that benefits the battery itself, although it may provide a slightly more accurate % charge for a while. The BMS is pretty good on its own, and adapts to battery conditions, including aging, with normal use.

It might be something to do if a convenient opportunity presents itself. But it is not something i would make any plans to do regularly. I charge my cars daily to 75%, and rarely get below 60%, especially now with Covid travel restrictions in play. Set the tank indicator to "Energy" (displays battery %) and don't stress over it.

 

[tomas]

If you regularly drive distances that require accurate estimate, then a few cycles of <20 to ~90 will improve the BMS’s estimate. 1 cycle will not do much. Going to 0 is unnecessary and risky. Going to 90 occasionally and leaving at that level overnight will ensure cells balance.

For most people, who do not regularly use all the range, all of this is not necessary. Agree it is advisable for most to set at %, plug in every night and charge to 80ish%. Only other caution is leave at 50-60% if you are on vacation or otherwise gone for extended period.

 

[AlbertEgger]

I do drive once in a while to <20%, but as I understand you guys right now, there is absolutely no need in this case to charge to 100% for calibration. Correct?

 

[DCGOO]

I do drive once in a while to <20%, but as I understand you guys right now, there is absolutely no need in this case to charge to 100% for calibration. Correct?

Correct

 

[Fiver]

As others have mentioned, the whole 0-100 calibration thing doesn't really change anything about the physical condition of your battery. All it does is allow the battery management system to get a better reading on the condition of said battery.

So while it's nice to think you have gained a few extra miles or whatever after a calibration, in all honesty nothing has actually changed beyond the number on the screen.

That said, I still try and do a low single digit to 100% (and then drive back to down to below 90% after hitting 100%) about once every year to 18 months. If anything it's just to get a sense for how my battery is aging. It's not like there's anything I can do to change the battery condition. I follow best practices, but batteries wear out over time regardless of use. Can't stop age.

 

[house9]

This is a good read about BMS calibration:

https://teslamotorsclub.com/tmc/threads/how-i-recovered-half-of-my-batterys-lost-capacity.204712/

 

[Rocky_H]

Hello,

Some people are claiming, that once a year I should drive my battery to 0% and then charge it to 100% with the idea, that the BMS knows what capacity the battery has and to balance the cells.

Others say, driving to 0% is not healthy for the battery and should be avoided , it’s long it’s not badly needed. The BMS calibrates itself automatically and the battery is also balanced all the time when needed.

So, what is true? Should drive my battery once a year down to 0% and charge it to 100%? Or is this not needed at all?

Both are true for different purposes. Here is same question and my answer from a thread in 2018.
Who wants in on a class action lawsuit? ;-)

 

[tomas]

Both are true for different purposes. Here is same question and my answer from a thread in 2018.
Who wants in on a class action lawsuit? ;-)

BS. No reason ever to drive to or near zero. None.

 

[Rocky_H]

BS. No reason ever to drive to or near zero. None.

Well, that's certainly false. It does do something, so that is a reason.
That's an entirely different question, which you misunderstood when you put a disagree on my post. Is it a good thing to do, or something I would recommend? No, generally not. It causes harm to the battery, so I consider it unnecessary. It has a purpose, to true up that number on the screen, but it's overall a little bit harmful, so I don't advise people to do it just to get some feel-good about a number on a display.

 

[tomas]

Well, that's certainly false. It does do something, so that is a reason.
That's an entirely different question, which you misunderstood when you put a disagree on my post. Is it a good thing to do, or something I would recommend? No, generally not. It causes harm to the battery, so I consider it unnecessary. It has a purpose, to true up that number on the screen, but it's overall a little bit harmful, so I don't advise people to do it just to get some feel-good about a number on a display.

0% won’t true it up any better than 2%-5%. So why go there? Your post says you do periodic 0-100 charge for a reason. If you had said 5-100, I would not have disagreed.

there’s way too much bad advice on this forum, which is why the gut reaction to 0.

 

[Rocky_H]

0% won’t true it up any better than 2%-5%. So why go there? Your post says you do periodic 0-100 charge for a reason. If you had said 5-100, I would not have disagreed.

there’s way too much bad advice on this forum, which is why the gut reaction to 0.

I DARE you to quote me where I EVER said I do that. I DON'T! And I specifically said that it is bad for the battery! Damn.

 

[tomas]

Sigh... convoluted reply with link to earlier reply... I reread it and again came to same conclusion: someone asked about charging 0-100, citing opposite opinions on necessity. You said “both are true” and used low to high in your reply vs 0-100, but did not call out 0 as a bad idea. Which I read and re-read as saying there’s a case and a use for 0-100 cycling.

I’m glad you are so passionately clarifying that you oppose this advice and practice. If I had posted what I did except not as a reply to you and without disagreeing with your post, you would have agreed with it, right? Peace!

Again, the reason I get so passionate about this is that we have lots of new owners on this site dealing with their first EV, and getting wrapped around the axle over battery maintenance. They need unambiguous information: don’t run it to 0 just to try to improve the estimation. It’s the same as intentionally running out of gas in an ICE car, and who would do that?

 

[Rocky_H]

You said “both are true” and used low to high in your reply vs 0-100, but did not call out 0 as a bad idea. Which I read and re-read as saying there’s a case and a use for 0-100 cycling.

Huh. Well, I will paste the original text and highlight it:

The 20%-80% recommendation is what to do for your constantly daily habitual process to achieve the least physical damage and longest possible life of the batteries.

I explicitly said that keeping toward the middle state of the battery state of charge causes the least damage to the battery, contrasting that with next explaining what the low/high does for the display number. I guess I did not flat out tell people, "Don't intentionally damage your battery!", but I thought that was a given.

 

[AlbertEgger]

I brought my car this morning for the 2 years maintenance and while I was at the service center, I've asked them what the think about it. To get the battery balancing started, the car has to be driven bellow 20% and then charged to 90%, drive it again bellow 20% and charge it again to 90%. Important is not to charge it in between and repeat it up to 3 times. Also important to know is, that the balancing will only start, if the BMS think it's necessary.

 

[tomas]

I brought my car this morning for the 2 years maintenance and while I was at the service center, I've asked them what the think about it. To get the battery balancing started, the car has to be driven bellow 20% and then charged to 90%, drive it again bellow 20% and charge it again to 90%. Important is not to charge it in between and repeat it up to 3 times. Also important to know is, that the balancing will only start, if the BMS think it's necessary.

Huh? Are you confusing balancing and calibration?

 

[AlbertEgger]

Huh? Are you confusing balancing and calibration?

No, I'm not. The Tesla employee clearly stated, that this should trigger the balancing.

 

[webbah]

No, I'm not. The Tesla employee clearly stated, that this should trigger the balancing.

Hi Albert, and greetings from Geneva. I can't speak for the Model X, but essentially the same applies. With my Model 3 I have never had any issues and I don't even have a plug at home (rented apartment) to charge. I've had Tesla's since 2012 starting with a Roadster 2.5. In the Model 3 the first thing I did is change the screen to show % instead of kilometers range. So many things can alter the readings here like weather changes, headwinds, etc. It only causes range anxiety and is pointless in my opinion. I think that Tesla should instead have the default as %. I drive between Geneva and Lucerne at least once a week. I mostly use DC charging instead of AC (70% of charge lifetime on DC) and I have only 2.4% degradation in 30,000 Kilometers since new. This is better than expected and I keep a very close eye on my car.

Most of the time during the week my car never drops below 50% and I typically keep it charged at 90%. I honestly would not worry about things too much as on the forums things get blown out of proportion when people see range in kilometers or miles dropping and don't understand that it's typically more about weather changes more than anything else. Just wait until Winter really arrives and watch the trend in posts showing up in the forums.

 

[T.R.T.e.s.l.a.]

Huh? Are you confusing balancing and calibration?

And what's the difference between those?

 

[T.R.T.e.s.l.a.]

Hi Albert, and greetings from Geneva. I can't speak for the Model X, but essentially the same applies. With my Model 3 I have never had any issues and I don't even have a plug at home (rented apartment) to charge. I've had Tesla's since 2012 starting with a Roadster 2.5. In the Model 3 the first thing I did is change the screen to show % instead of kilometers range. So many things can alter the readings here like weather changes, headwinds, etc. It only causes range anxiety and is pointless in my opinion. I think that Tesla should instead have the default as %. I drive between Geneva and Lucerne at least once a week. I mostly use DC charging instead of AC (70% of charge lifetime on DC) and I have only 2.4% degradation in 30,000 Kilometers since new. This is better than expected and I keep a very close eye on my car.

Most of the time during the week my car never drops below 50% and I typically keep it charged at 90%. I honestly would not worry about things too much as on the forums things get blown out of proportion when people see range in kilometers or miles dropping and don't understand that it's typically more about weather changes more than anything else. Just wait until Winter really arrives and watch the trend in posts showing up in the forums.

Displayed km or miles related to state of charge, don't change due to weather conditions.