Not that I know of. I've been charging to 90% every day because that's what the service center told me to do.

 

Charge to what you need - there is no memory effect to worry about like older battery chemistries. The lower the day-to-day charge the better for longevity but as Jason says - 90% is totally safe day to day.

 

I am totally aware of the fact about 90% daily charging and I think i winters even going a bit higher will have negligible effect in battery degradation. I asked this question because I have never charged to 100% at all and never had the need.

 

Charging to 100%, like you suggested, every few months allow the batteries to equalize. At least go above 90%.

 

What does it mean to "allow the batteries to equalize"?

 

I’ve seen elsewhere on the forum the opinion that fully cycling the charge state has value, something about a “recalibration” of some unspecified process. I don’t see the sense of this, but I think it illustrates that we attribute models of behavior to EV systems that aren’t really valid. I think “equalizing banks” may fall in this category. I suspect that charge management is very well-managed by the computers.

 

With thousands of batteries in the pack and the physical chemistry slightly different in each one, the rate of charge and discharge of each individual battery will vary. If you charge to 80%, what happens is that some batteries may not charge all the way, maybe 50%, and then others make up the difference going to 90%. So they end up with differences of state of charge. By going to somewhere over 90%, let's say 100%, the battery management system can watch the batteries and bring everyone as close as possible to the 100% SoC.
Also, the BMS can then recalibrate some of it's numbers and will then better indicate the real SoC of the battery.

I'm not sure about Tesla's but in most other 18650 usage (all of your phone power banks and such) each battery has the BMS built into the container, the top 1/2 inch of the battery is actually circuitry. This circuitry helps make sure that each battery doesn't overcharge and blow up.

 

What @Ed Woodrick mentions was certainly true for submarine batteries. Yes, we had a big battery even on a nuclear submarine as back-up in case the reactor scrammed while we were at depth until we could either restart the reactor or surface to start up the emergency diesel.

Periodically we would perform an "equalization" charge: Run the battery down very low and then charge it all the way to the top. Granted, the submarine battery was lead acid, and this is a significantly newer and more efficient technology, but I think the same principle still probably applies, particularly with allowing the Battery Management System to recalibrate as well. I am not an expert on Lithium battery technology, so it could be that what @MJJ is saying is true, that I'm applying old thinking to new technology, but I also believe some fundamental underlying principles of battery management remain unchanged.

I also recall a post elsewhere on the forum suggesting the full discharge and recharge to calibrate the M3's battery meter, and it seemed to have worked.

Early in my ownership I did cycle the battery on my M3 for this reason, down to about 7%, then up to 100% (so everything could equalize and calibrate), but never again since then. I will be charging to 100% tomorrow night, however, for a road trip (210 miles round trip, temperatures in the 20s). More on that in a separate post after the trip is over.

 

Ed, you’re helping me make my point. With the layers of insulation, I really doubt there’s anything the end user can do, aside from avoiding deep cycle and rapid charge situations as mentioned in the owners manual, to “help” maintain the system.

For example, if it was important to deep cycle components, the BMS could do that invisibly, by selectively under or over charging or draining a specific bank.

 

With thousands of batteries in the pack and the physical chemistry slightly different in each one, the rate of charge and discharge of each individual battery will vary. If you charge to 80%, what happens is that some batteries may not charge all the way, maybe 50%, and then others make up the difference going to 90%. So they end up with differences of state of charge. By going to somewhere over 90%, let's say 100%, the battery management system can watch the batteries and bring everyone as close as possible to the 100% SoC.
Also, the BMS can then recalibrate some of it's numbers and will then better indicate the real SoC of the battery.

I'm not sure about Tesla's but in most other 18650 usage (all of your phone power banks and such) each battery has the BMS built into the container, the top 1/2 inch of the battery is actually circuitry. This circuitry helps make sure that each battery doesn't overcharge and blow up.

I could be wrong... I believe the BMS is capable of balancing the cells without ever needing to take them all the way to 100% (or all the way down for that matter). Balance only matters instantaneously...So long as the cells are the same. I doubt there is any historical values stored for 'this particular cell needs more juice when charging because it has different chemistry'. It just says at all times 'this cell is low, balance it'.

 

My cousin how is an electrical engineer for a large power company told me to cycle it every so often to load balance it... so that is what I am doing.

My process is that I get it to a 100% full state of charge —> go for a fast Angeles Crest Canyon run —> use up the rest of the battery over the weekend —> then bring it back up to 80% SOC for my daily commute

 

The murmurings suggesting to charge to 100% to "equalize" does not serve any benefit to the battery itself, it was simply to help the software calibrate and better estimate the maximum range.

Cell balancing happens at all but the lowest charge levels and can occur at any time when the battery management system determines there is too much difference between cell voltages.

So please don't think you should charge to 100% for the health of your battery, in fact the reverse is true. But go ahead and do so if you will be immediately leaving on a trip where you need the extra range.

 

Gosh, ALL yups!

Pack balancing in Roadsters was a common strategy with their oldish packs and BMS but is no longer needed IMO.

The delivery folks often recommend charging to 90% because that is what they were instructed to say in order to keep things simple. Since I am afflicted with car OCD (on my several ICE cars/trucks as well) and I keep my cars forever, I only charge to the level I need plus a cushion. This strategy has worked very well for 6+ year old Big sis Veronica with 85,000 miles and spending the majority of her life between 70 and 40% SOC with mostly an 80 RT commute. 11 month old Little sis Ana still has not been charged to 100% SOC. Since we drive our NEVs the majority of the time now, both the S and 3 sit at 50%.

 

With thousands of batteries in the pack and the physical chemistry slightly different in each one, the rate of charge and discharge of each individual battery will vary. If you charge to 80%, what happens is that some batteries may not charge all the way, maybe 50%, and then others make up the difference going to 90%. So they end up with differences of state of charge. By going to somewhere over 90%, let's say 100%, the battery management system can watch the batteries and bring everyone as close as possible to the 100% SoC.
Also, the BMS can then recalibrate some of it's numbers and will then better indicate the real SoC of the battery.

I'm not sure about Tesla's but in most other 18650 usage (all of your phone power banks and such) each battery has the BMS built into the container, the top 1/2 inch of the battery is actually circuitry. This circuitry helps make sure that each battery doesn't overcharge and blow up.

Everything you need to know and more on how the Model 3 2170 batteries are made, assembled and managed.

 

What I want is the option to have it finish charging to 100% at a certain time. Like, this Saturday I'm going on a trip and I'm leaving at 0600. I want the battery to finish charging at, say, 0545.

 

so the night before, from the car's screen, toggle off the scheduled charging. When it begins charging, note the hours it needs to charge. Turn scheduled charging back on and adjust the charge start time based on the hours needed to charge to end at 5:45a. the whole process takes 10 seconds max.

 

For the first time in about 6 months or more, I decided to charge to 100%. We have a long drive to do today, so it won't stay at 100% for very long.

Getting into the car and looking at the display, the miles seem to be stuck on 315 miles, the remaining time has been 30 minutes for at least 30 minutes and the current is bouncing up and down.

The current is rapidly fluctuating between 24A (the limit) and 3A. It seems somewhat odd. Perhaps some kind of cell balancing or calibration is taking place?

 

Yep, the batteries are calibrating and it can take a LONG time.
And back to my original statement, you need to go to at least 90% to get the batteries to equalize. Not only does this reset the computer, it brings all of the batteries back to close to the same voltage.

 

Yep, the batteries are calibrating and it can take a LONG time.
And back to my original statement, you need to go to at least 90% to get the batteries to equalize. Not only does this reset the computer, it brings all of the batteries back to close to the same voltage.

I don't think that 90% is sufficient. In the case above, where I charged to 100% and it spent a lot of time calibrating/balancing, I had previously charged to over 90%, then, before driving, I increased the charge limit to 100% and re-started charging. Had 90% been sufficient for calibration/balancing, it would not have needed to spend all that time to go from 90% to 100%, with fluctuating current.

 

So folks that are now leasing the Model 3 do not likely care very much about the life of the battery in their car. I wonder if most of them will charge to 100%? On the LR models it's not a huge difference - 279 vs 310 but still.... miles matter.

 

And Tesla would probably like to think that the battery will have significantly over 100k miles, even if they don't care about the battery.

 

Yep. But Tesla is planning to use these leased cars as Robotaxis at the end of the lease (they won't even give you the option to buy it at the end of the lease). Most of these cars will come back to Tesla with 30K to 45K miles put on them. If the batteries are abused during those miles you have to wonder how much longer they'll actually last?

 

You can't abuse a battery that badly. And without free supercharging, it really is hard to abuse the battery.

 

Which kinda of makes you wonder why the big push/scare to tell folks to only charge to 90% of their battery's capacity right?

For the record - I do think it's best to not charge to 100% all the time. I'm just trying to think through what this really means for the masses and how leasing affects the equation.

I can assure you that 95% of the folks leasing their Teslas are most likely charging to 100% every single time. If that does degrade the battery over time, it won't have any impact during the (relatively) short lease period.

 

this topic has been discussed ad nauseam, a simple search of any tesla forum will generate dozens of threads and hundreds of comments.
the only thing tesla owners should know about their battery is that it is bad for the car's SOC to remain at over 100% or under 10% for any extended amount of time. In other words if you are leaving for a road trip or are in the midst of one it is safe to charge to 100% providing you start to use the car ASAP, on the flip side if you run the car down to under 10% you really should get the car charged up before having dinner or going to sleep for the night. occasional violations of those parameters would probably not cause any harm to the battery but continual violations of those parameters does not help the health of the battery.
As an aside if charging to 100% was so bad for the battery don't you think that the engineers would have blocked the ability to do so?

 

Agreed on all points. There's really no debate that charging to 100% isn't ideal for the battery. But as you stated, if it were really harmful then I'm sure the engineers would prevent us from doing so.

All of which is the exact point of my comment. If you own the car then it's in your best interest to care for it as best you can. If you're renting the car for 3 years... most won't care. It's just human nature.

 

Keep in mind that if you charge to 100% even just 2 or 3 times in a few day period, you get a warning in the car. I've had it. I was making a 200 mile trip in cold weather. Charged to 100% when I left and again at my destination. I received a warning on the screen about the 100% charges and shouldn't do it if not required.

I'm quite certain that Musk is just smart enough and the kind of guy that a small software update might even assist if they find a leased or any car consistently charging to 100% and not needed. The SW could take it a step further than just a warning.

 

Keep in mind that if you charge to 100% even just 2 or 3 times in a few day period, you get a warning in the car. I've had it. I was making a 200 mile trip in cold weather. Charged to 100% when I left and again at my destination. I received a warning on the screen about the 100% charges and shouldn't do it if not required.

I'm quite certain that Musk is just smart enough and the kind of guy that a small software update might even assist if they find a leased or any car consistently charging to 100% and not needed the SW could take it a step further than just a warning.

That's great that they will show you a warning message actually! And I agree that it might be a great idea to software limit the charging to 90% on leased vehicles if they find a constant repeat offender.

 

And don't forget that the cars that have the highest mileage (>400k) do indeed Supercharge multiple times a day.

People keep treating these batteries as if they are delicate items that will only work within specific situations, where, in reality, they are extremely robust. That's why you see so very little recommendations from Tesla about battery care.

 

Elon says 100% is safe. its just that since the battery is so full, theres no regen and its terribly inefficient. I have personally found that the first "top" couple of miles burn off 3-4 times faster. i.e. from 300miles to 300 miles takes about 3 miles of driving - even being careful not to require regen. miles 290-300 are used up in about 5 miles. miles 280-290 in about 6-8 miles. below 270 it seems more accurate.

 

Elon says 100% is safe. its just that since the battery is so full, theres no regen and its terribly inefficient.

Please read up on what maxing out a lithium battery does to the battery. You do not want to charge it to 100% and let it sit overnight like that. Hence Tesla's recommendation to charge to 90% or less.

 

As far as lease cars go, remember that Tesla has a vested interest in reusing/reselling them and Tesla knows how much the battery is being charged. So they can restrict it if necessary.

 

I leased a car once. In the 3 years I had it, the oil was never changed. People do abuse leased cars more than ones who buy them.

If I leased a Tesla, I’d definitely charge it to a higher SOC on a daily basis than what I do now.

 

But why spend time charging when you don't need to?

 

Because most people aren't sitting in their cars twiddling their thumbs while waiting on it to charge. They either plug in overnight or in a best case scenario (like me) charge up for free at work.

On the other hand - your point is also valid. If there's no time lost while charging then just charge it to 90% as needed and be done with it.

But I'm still of the opinion that a lot of people haven't gotten used to thinking about EV charging differently than they think about charging their phones. Get it as full as possible so that you don't have to worry about it again for a while.

 

Truth is people should not be charging their phones to 100% either. Esp overnight.

 

The reality is the opposite.