3:00 Very well explained video. Also the graphical representation is genius! How do you know that balancing happen during the 90-100 soc window? Could it be 85% or 95% to 100% too? Dod you checked out the BMS CAN messages? Thanks
Lithium packs need occasional balancing to maintain peak performance.. sort of like how we used to de-frag hard drives occasionally to restore performance.
I’d add that a grossly imbalanced pack will prematurely trigger the emergency shutdown message long before the display has reached 0% in the car, due to those low cells triggering the minimum voltage protections WAY before its anticipated in the coulomb counting method. We’ve all heard of those cars that are forced to pull over for the shutdown when the screen said there was like 5 to 8% “left” on the display. The power reduction that occurs below 20% tried to combat the amount of “sag” that can prematurely hit this protection but it stands little chance against a really unbalanced pack.
This also bring another important question: does imbalance process happen more at high state of charge? If the self discharge current inside the cell happen across an equivalent resistor value than the relationship between soc and unbalance process would also follow the OVC curve.
Yes, charging up to 100% will trigger the BMS to balance your pack. In fact, charging up to 90% or 93% may even cause the BMS to balance, but nobody seems to know for sure the exact SOC that triggers balancing. So I always just use 100% when I want to balance my pack because we know for a fact this SOC will trigger balancing. A couple times a year should be sufficient to keep the pack balanced. With regards to draining to 5% beforehand…this will allow your BMS to more accurately estimate your packs total capacity and thus allow for better range predictions.
Yup - charging up to 100% on a road trip would be ideal! I do it a couple times per year to ensure my battery never gets too unbalanced. I believe this is more of a problem for people that use ultra-conservative daily charge limits. For example, someone that never charge past 50% would be at a greater risk of their pack becoming unbalanced.
With the Sexy Buttons app, it's showing, instead of percentage, mV. 6 - 8 mV rn. That seems low to me offhand, but I have no frame of reference. What number would you think says, "Maybe we ought to cycle the battery?@@CosmologicalNonsense
Any suggestions for NCA cars that won't charge to 100? Mine often stops in the low 90s with 'charging complete' and won't go any higher. Both with L2 and SC.
Hmmm…I’m not sure. My only suggestion would be to search the TeslaOwnersOnline and TeslaMotorsClub forms - there are some really smart people on there.
is this fittable for NCA/NMC batteries? I got M3 LR and tessie shows a big degradation during last ~10 charges. Capacity dropped from 67-68 to ~62, though I did not discharge it much or charge it to 100 and leave for a lot of time. Usually discharge it to ~40% and charge to 80%, very mostly I use AC charger with up to 25 amps
Yes, this video is specifically for the nickel cobalt battery chemistry. If you’ve never charged your pack up past 80-90%, I’d say it’s worth a shot. Charge it all the way, then drive around to bring the state of charge back down to a reasonable level….This will trigger the pack to balance. Over the next several days and charge cycles, you may see an improvement (assuming the pack was unbalanced to begin with).
@@CosmologicalNonsense Car was taking around 18amps on 230V on 100% of charge. I have been waiting for around a hour and it dropped to like 10-12 amps, but I didnt have any more time to wait so had to drive. I did the trick just in case when I bought the car, it had like 450km range, I charged it to 100% and left for around a day without driving, I know its bad but range increased to 470km. Since then I only charged to 95% for trips and usually to 80% while discharging to 30-40%. Looks like I had to wait now until the charging has stopped but I guess Ill see the difference anyway. If range will increase, then after a month or two I will repeat but this time will wait until it stops charging and wait for a half an hour after before "test drive" to discharge battery. What I can say your trick really works because once I had an increase for around 20km. Big thanks for the video, its really easy to understand the technology in an easy way. Good Luck man
Great question. I am an engineer with a background in battery packs. But more importantly, Tesla's BMS has been deconstructed and analyzed by qualified enthusiasts and they have observed, documented, and described this passive balancing process in extreme detail.
@@CosmologicalNonsense it sounds odd that the BMS requires a 100% SoC to start the balancing process when Tesla advices customers to basically never charge to 100%. Are there other triggers for the balancing process?
@@44Bigs Yes, you are correct! The BMS begins balancing the pack at a SoC less than 100%....but nobody seems to be sure exactly what SoC triggers it. So I typically use 100% when I want to force the pack to balance, because everybody can agree this SoC will absolutely trigger balancing. Then I just drive the car afterwards to bring the SoC back down to something more reasonable. Doing this once or twice a year doesn't seem to be problematic.
Correct - the balancing will begin while topping off the pack, and will finish several hours later (or even a day later if your pack was severely unbalanced). You don’t need to let the car sit still while it is balancing - the car can be driven or parked during this period.
3:00 Very well explained video. Also the graphical representation is genius! How do you know that balancing happen during the 90-100 soc window? Could it be 85% or 95% to 100% too? Dod you checked out the BMS CAN messages? Thanks
Lithium packs need occasional balancing to maintain peak performance.. sort of like how we used to de-frag hard drives occasionally to restore performance.
I’d add that a grossly imbalanced pack will prematurely trigger the emergency shutdown message long before the display has reached 0% in the car, due to those low cells triggering the minimum voltage protections WAY before its anticipated in the coulomb counting method.
We’ve all heard of those cars that are forced to pull over for the shutdown when the screen said there was like 5 to 8% “left” on the display. The power reduction that occurs below 20% tried to combat the amount of “sag” that can prematurely hit this protection but it stands little chance against a really unbalanced pack.
This also bring another important question: does imbalance process happen more at high state of charge? If the self discharge current inside the cell happen across an equivalent resistor value than the relationship between soc and unbalance process would also follow the OVC curve.
Nice video, thank you
So just like you’re charging to 100, I’m assuming we should drain to at least 5% before hand?! What’s your thought on that?
Yes, charging up to 100% will trigger the BMS to balance your pack. In fact, charging up to 90% or 93% may even cause the BMS to balance, but nobody seems to know for sure the exact SOC that triggers balancing. So I always just use 100% when I want to balance my pack because we know for a fact this SOC will trigger balancing. A couple times a year should be sufficient to keep the pack balanced.
With regards to draining to 5% beforehand…this will allow your BMS to more accurately estimate your packs total capacity and thus allow for better range predictions.
How often should you do this? Will Charging to 100%, then doing a road trip achieve the same result?
Yup - charging up to 100% on a road trip would be ideal! I do it a couple times per year to ensure my battery never gets too unbalanced.
I believe this is more of a problem for people that use ultra-conservative daily charge limits. For example, someone that never charge past 50% would be at a greater risk of their pack becoming unbalanced.
With the Sexy Buttons app, it's showing, instead of percentage, mV. 6 - 8 mV rn. That seems low to me offhand, but I have no frame of reference. What number would you think says, "Maybe we ought to cycle the battery?@@CosmologicalNonsense
Any suggestions for NCA cars that won't charge to 100? Mine often stops in the low 90s with 'charging complete' and won't go any higher. Both with L2 and SC.
Hmmm…I’m not sure. My only suggestion would be to search the TeslaOwnersOnline and TeslaMotorsClub forms - there are some really smart people on there.
is this fittable for NCA/NMC batteries? I got M3 LR and tessie shows a big degradation during last ~10 charges. Capacity dropped from 67-68 to ~62, though I did not discharge it much or charge it to 100 and leave for a lot of time. Usually discharge it to ~40% and charge to 80%, very mostly I use AC charger with up to 25 amps
Yes, this video is specifically for the nickel cobalt battery chemistry.
If you’ve never charged your pack up past 80-90%, I’d say it’s worth a shot.
Charge it all the way, then drive around to bring the state of charge back down to a reasonable level….This will trigger the pack to balance.
Over the next several days and charge cycles, you may see an improvement (assuming the pack was unbalanced to begin with).
@@CosmologicalNonsense Car was taking around 18amps on 230V on 100% of charge. I have been waiting for around a hour and it dropped to like 10-12 amps, but I didnt have any more time to wait so had to drive. I did the trick just in case when I bought the car, it had like 450km range, I charged it to 100% and left for around a day without driving, I know its bad but range increased to 470km. Since then I only charged to 95% for trips and usually to 80% while discharging to 30-40%. Looks like I had to wait now until the charging has stopped but I guess Ill see the difference anyway. If range will increase, then after a month or two I will repeat but this time will wait until it stops charging and wait for a half an hour after before "test drive" to discharge battery. What I can say your trick really works because once I had an increase for around 20km. Big thanks for the video, its really easy to understand the technology in an easy way. Good Luck man
How do you know this?
Great question. I am an engineer with a background in battery packs. But more importantly, Tesla's BMS has been deconstructed and analyzed by qualified enthusiasts and they have observed, documented, and described this passive balancing process in extreme detail.
Thanks for the response! Would love to find out more about this stuff.
@@mk061g9a ton of information can be found by looking around on the teslamotorsclub.com forum. They have some really knowledgeable contributors.
@@CosmologicalNonsense it sounds odd that the BMS requires a 100% SoC to start the balancing process when Tesla advices customers to basically never charge to 100%. Are there other triggers for the balancing process?
@@44Bigs Yes, you are correct! The BMS begins balancing the pack at a SoC less than 100%....but nobody seems to be sure exactly what SoC triggers it. So I typically use 100% when I want to force the pack to balance, because everybody can agree this SoC will absolutely trigger balancing. Then I just drive the car afterwards to bring the SoC back down to something more reasonable. Doing this once or twice a year doesn't seem to be problematic.
So let it for few hours after discharging to 90%??
Correct - the balancing will begin while topping off the pack, and will finish several hours later (or even a day later if your pack was severely unbalanced).
You don’t need to let the car sit still while it is balancing - the car can be driven or parked during this period.
@@CosmologicalNonsense ok so I can drive it.. I thought I must leave it without driving for few hours at least.. THX I will try
@@juradostyyup - you can drive right away and it will still balance in the background.