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New video we just released - How to balance your Battery

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31K views 94 replies 29 participants last post by  Feathermerchant  
#1 · (Edited)
Hey guys,
We just released a new video that details the battery balancing process on my 2022 Model 3 Long Range.
You may remember I posted a similar video a few weeks ago, but some folks smarter than me pointed out a few mistakes.

I've corrected the mistakes, and the updated video can be seen below.
Thanks for watching!

 
#4 ·
Nicely done video..this is what I normally practice, every 90-120 days depending on usage. I can get my 2018 M3 LR back to ~ 310-312 range which is right about what it was rated at ? 315 ?… sure would like to have a rated 355 though, that’s a nice improvement in three to four years of engineering and battery pack design.

Question though. Is this just a big oversimplification or is this really how capable accessible energy is reduced over time and how it can be re-accessed through the 90-100% BMS process that the car enables?
 
#5 · (Edited)
Nicely done video..this is what I normally practice, every 90-120 days depending on usage. I can get my 2018 M3 LR back to ~ 310-312 range which is right about what it was rated at ? 315 ?… sure would like to have a rated 355 though, that’s a nice improvement in three to four years of engineering and battery pack design.

Question though. Is this just a big oversimplification or is this really how capable accessible energy is reduced over time and how it can be re-accessed through the 90-100% BMS process that the car enables?
Thanks for watching. I'm sure there is a lot happening behind the scenes with the car's computer and BMS while charging/balancing, but the overall concept is absolutely accurate.

The biggest point I wanted to get across, is that a small imbalance in one series stage will strand energy in all other stages when the pack is nearly empty. One low stage infects the entire pack, which is why balancing is so important when trying to maximize performance.

And of course, there will always be unrecoverable chemical degradation. But we've seen several cases where super conservative daily charge limits (50-60%) on relatively new cars cause the pack to become wildly unbalanced which dramatically reduces the range....then balancing solves the problem.
 
#8 ·
I have a 2018 M3P, a 2020 M3P, and a 2021 MY. They show calculated degradation ranging from 10 to 14 percent. I've never let any of them sit at 100% for more than a couple of minutes. I'm currently charging the 2020 to 100% using L2. I'll report my results in a few hours. Thanks for this, fingers crossed!!
 
#9 · (Edited)
I'm currently charging the 2020 to 100% using L2
I wonder if that might explain my car/Navigation insisting I charge to 100% on my recent long trip? Hmmm. I was at a Supercharger too, it was hard to do but I did it. I didn't notice much of any change however. Keep us posted @FRC
 
#14 ·
In the Model 3 and Y there are 96 series sets of 46 cells in parallel. So the loss of one cell in the 46 would reduce capacity in that set by 1/46 or about 2.2%. But because that set of 46 is in series with 95 other sets of 46, the whole pack possibly has reduced capacity depending on how the BMS works. If it can compensate for that cell loss then the pack loss is only about 0.023%.
The total number of cells in the pack is 46 X 96 = 4,416
There is a dongle you can buy so you can hook up a Bluetooth adaptor and read the CAN bus messages then use the 'Scan My Tesla' app to view battery voltages. Here is a screenshot from my 2018 Model 3 Performance. It is normally charged to 80% and has about 35,000 miles on it. You can see the high and low cell voltage differs by 4.012 - 4.006 = 0.006 Volts. I would not expect much more range from further balancing.
 

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#17 ·
In the Model 3 and Y there are 96 series sets of 46 cells in parallel. So the loss of one cell in the 46 would reduce capacity in that set by 1/46 or about 2.2%. But because that set of 46 is in series with 95 other sets of 46, the whole pack possibly has reduced capacity depending on how the BMS works. If it can compensate for that cell loss then the pack loss is only about 0.023%.
The total number of cells in the pack is 46 X 96 = 4,416
There is a dongle you can buy so you can hook up a Bluetooth adaptor and read the CAN bus messages then use the 'Scan My Tesla' app to view battery voltages. Here is a screenshot from my 2018 Model 3 Performance. It is normally charged to 80% and has about 35,000 miles on it. You can see the high and low cell voltage differs by 4.012 - 4.006 = 0.006 Volts. I would not expect much more range from further balancing.
Great information. I agree - your pack seems well balanced. A 6mV delta across all 96 parallel groups is pretty tight.

It may have not been clear in the video, but in packs with series/parallel combinations (like the tesla pack), the individual cells within a parallel group will never become unbalanced. Since the anodes are physically connected, and the cathodes are physically connected, the individual cells within a parallel group will always stay at exactly the same voltage. A weak individual cell will just syphon juice from its neighbors in the parallel group and stay at exactly the same voltage as the other cells that it's connected to. Parallel groups of individual cells kind of "self balance" each other.

So I typically think of parallel groups as one giant single cell.

In the tesla pack example you laid out, there will be 96 groups in series. The imbalance will not occur on an individual cell basis. The imbalance would occur in one of the 96 parallel groups.
Balancing will bring all 96 parallel groups to the same voltage (within some mV tolerance of course).

If I were you and had not balanced my pack in 5 years, I would probably give it a shot for peace of mind.
Anyway, thanks again for sharing.
Cheers
 
#15 ·
Hey guys,
We just released a new video that details the battery balancing process on my 2022 Model 3 Long Range (not to be confused with "recalibration").

When recalibration is discussed online, I often see responses correctly saying "this will not extend your range, it just tweaks the range-calculating algorithms"
This is not the case when it comes to pack balancing. Balancing puts actual energy into the pack that can come back out on the road to extend range.

Most lost range is obviously caused by natural unrecoverable chemical degradation. But lost range due to cell imbalance can absolutely be recovered by balancing the pack.

I hope you enjoy....cheers!
Very professional video, clear and easy to understand.

As I post this, I'm charging the battery to 99%. When it gets there I will change the limit to 100% to watch the BMS do its thing.
 
#18 ·
Just finished my 2020 M3P. As I alluded to earlier, I'm pretty good about exercising the limits of the battery (through both charging and driving habits). So, I was unsurprised that this procedure yielded no change in my car. Charging droppped to 0a immediately upon reached 100% SOC. Range remained 279 pre- and post-procedure.

Now, I've long suspected that my wife's 2021 MY is unbalanced. So, I'm now charging her to 100%...we'll see.
 
#27 · (Edited)
Just finished with the 2021 MY. Same procedure, same results. And my wife (her car) is a devote 80-30% behavior pattern. I was expecting to see some increase, but no joy. BTW, the reported 2-3 mile increases can easily be attributed to rounding.

I tried, but I'm not a convert.
 
#23 ·
I’m mid process. What I’m experiencing is that the car has been at 99% for a while. That is different from video which suggests will show 100% but keep charging.

Has stated ‘30 minutes remaining’ for over an hour. Amps now down to 5.

Before started calculated 100% was 283 miles. Now showing 285.

2018 Model 3 LR …67K miles. I think original max was about 310. If stays at 285 will be 8% loss.

…..

Well, before posting just checked. From 30 minutes to go … to done. 285 is the number. Have never fully charged like this. Will let it sit for 15 minutes or so and then go for a drive
 
#26 · (Edited)
This has been the most intelligent and informative video I've watched about battery balancing. Very informative without being too complicated. Thank You! Mine is due soon, will come back and let you know. Stored mine for 4 months last winter. Went from 425 to 409 range, didn't worry too much about since I knew balancing and algorithmes probably had lots to do with it. I worked with batteries all my life mainly nickel metal hydride, they were a pain. I used to deep freeze them to restore life. I'd get an extra year out of them of daily use.
 
#31 · (Edited)
Yes, balancing can begin in as the SOC approaches 100%. I discuss this point earlier in this thread, and touch on this fact in the video when showing the Voltage vs. SOC curve and say “balancing will only take place on the knee of the curve as the State of Charge approaches 100%”

Most of the other balancing instructions I found typically say something along the lines of “charge to 100% and wait for current to stop” so I decided to shoot the video following that process, as it seemed to be the easiest/clearest set of instructions.

Thanks for the feedback!


EDIT: this article was one of our sources used while creating the video.


CELL BALANCING:
  • Plug the car in to charge, preferably on a AC charging point although you can also do this on a rapid chargerbut it may block it for others for some time.
  • Set the charge limit to 100% and leave the car to charge.
  • When the car reaches what appears to be 100% it may well say it has finished charging but it is drawing current. Leave the car charging until it indicates no energy is being added to the battery. This can take some time (an hour or so) after the car appears to have reached 100%. The charge rate may drop to under 10A which is fine. Let the car do what it needs to do.
  • Eventually the battery will stop stop taking on current. Be mindful if you have the heating on, the car will still be taking current, but not for the purposes of charging the battery
 
#32 · (Edited)
I'm one of those daily 50-80% owners. Charging to 100% as I write this. I have never charged it to the limit yet in 10 months of ownership. When I first got my Y it would show 427kms @ 80% SOC, it is now 408kms. I know the battery hasn't degraded that much in 10 months so hopefully this recal of the system via BMS will help restore my range numbers a bit. I don't expect 427 but 420 would be encouraging. Will post later with my findings.

It dropped from 32 amp to 31 at 98% and showing 500 kms of range.
Image


99% and 505kms of range. Current flow has dropped to 27 amps. So far everything in the video is smack on the button.

Image

Down to 12 amps

Image


Eventhough the APP shows 1 amp steps for current it is actually a slow decrease as my meter shows.

Also took this opportunity to measure temperatures. The 10-40 connector was the warmest with the breaker a close second everything else was at room temperature. All was expected and normal.

Image

Image
 
#34 ·
I liked the video. I gave it a try. Unfortunately, I relied on the app's remaining charging time to gauge when to return to the car to watch the ending charge, and the car had finished about 20 minutes sooner than predicted.

I did however notice a DROP in full charge miles. My car has shown 295 miles on a full charge sinice I bought it used last year, and now shows 293.

With that said.... I really don't put much stock in the charging numbers that I see on the screen. I 1000% believe that charge numbers and energy usage can be, and are, altered by Tesla during updates. Not saying that it's intentional (also not ruling it out either), but I have seen it several times on my car on various updates.
 
#35 ·
I liked the video. I gave it a try. Unfortunately, I relied on the app's remaining charging time to gauge when to return to the car to watch the ending charge, and the car had finished about 20 minutes sooner than predicted.

I did however notice a DROP in full charge miles. My car has shown 295 miles on a full charge sinice I bought it used last year, and now shows 293.

With that said.... I really don't put much stock in the charging numbers that I see on the screen. I 1000% believe that charge numbers and energy usage can be, and are, altered by Tesla during updates. Not saying that it's intentional (also not ruling it out either), but I have seen it several times on my car on various updates.
Thanks for sharing your results. This is helpful information.

UPDATE: A technical error was just brought to my attention in the video regarding my description of the balancing process. I want the content to be accurate, so I'm removing the video so I can make can few tweaks. I will reupload the video after its been fixed. Thank you everyone
 
#38 ·
Hey guys,
We just released a new video that details the battery balancing process on my 2022 Model 3 Long Range (not to be confused with "recalibration").

EDIT: after uploading the video yesterday, a technical error was brought to my attention regarding my description of the balancing process. I truly want the content to be accurate, so I'm going to make some tweaks to the video and re-upload.
Hi Iceman8247, not sure why, but I don't see the video in your post. Can you direct me to where to see it. Thanks
 
#53 ·
Hey man,
Yes, I am away from my office and have not been home to update the video. I realized after posting it had a technical error, and I dont want to add to the already confusing subject by posting a video with an error, so I removed it.

I feel like this post should be removed.

As soon as I fix the video, I will re-upload. But honestly, it’s going to be a week or two. Sorry guys.
 
#40 ·
I have a 2018 M3 LR. It was spec'd at 310 miles with 19" wheels. Best ever was 308 shortly after delivery.
About 2 years ago, it was down to 280 miles at 100%. I left it at the service center for some warranty work and right before a holiday weekend, they finished the car and left it plugged into a L2 charger, and set it to 100%. I watched this for 36 hours on the app, all pxxxxxd off at the car charging to 100% and sitting there like that all that time.

But when I picked up the car, at first very very angry at them, the miles at 100% were up to 290 miles.

Back then I suspected something like balancing happened, but my anger at the car sitting there that long at 100% changed to happiness. Perhaps its time to try the 100% thing again.
 
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#41 ·
Hey guys,
We just released a new video that details the battery balancing process on my 2022 Model 3 Long Range (not to be confused with "recalibration").

EDIT: after uploading the video yesterday, a technical error was brought to my attention regarding my description of the balancing process. I truly want the content to be accurate, so I'm going to make some tweaks to the video and re-upload.
when are you reposting the video please?
 
#42 ·
Hey guys,
We just released a new video that details the battery balancing process on my 2022 Model 3 Long Range (not to be confused with "recalibration").

EDIT: after uploading the video yesterday, a technical error was brought to my attention regarding my description of the balancing process. I truly want the content to be accurate, so I'm going to make some tweaks to the video and re-upload.
where can I find the video? thanks
 
#45 ·
Hey guys,
We just released a new video that details the battery balancing process on my 2022 Model 3 Long Range (not to be confused with "recalibration").

EDIT: after uploading the video yesterday, a technical error was brought to my attention regarding my description of the balancing process. I truly want the content to be accurate, so I'm going to make some tweaks to the video and re-upload.
Will you please direct us to the video, again?

TIA!
 
#52 ·
After posting the video, I communicated with a Tesla charging expert and realized I had a few technical errors. The whole point of the video was to help clear up confusion, and I felt a video with a technical error was doing the opposite, so I removed it from YouTube.

At some point over the next week or two, I plan to fix the video, but I am terribly busy at the moment.

I was hoping the mods would remove this post to avoid confusion.

Is it possible for me (as the creator) to delete this post?
 
#50 ·
I haven't been able to view the video yet, but my understanding is it might also be necessary to draw the battery down to 10% or less before charging to 90% or 100% (in order to really re-calibrate the state of charge optimally).