bms Do Inmotion battery packs perform cell balancing? Yes!

[Mono]

On 8/5/2023 at 9:28 AM, v8nice said:

problems with the battery which does not charge to the maximum (between 83.5 and 84v)

I am surprised you would think that charging to "only" 83.5V is a problem.

On 8/6/2023 at 12:09 AM, Chriull said:

Edit: PS: in wheels with not too much cells in parallel single cells were more easily overburdened and by this faster degraded. By this higher p count can give batteries  a longer live by less burden.

Isn't this completely independent of whether cells are in series or in parallel? 100W is 100W is 100W, after all. Or do you mean that a weak cell when put in series is more stressed when put in parallel?

[RagingGrandpa]

On 8/5/2023 at 3:28 AM, v8nice said:

problems with the battery which does not charge to the maximum (between 83.5 and 84v)

1 hour ago, Mono said:

I am surprised you would think that charging to "only" 83.5V is a problem.

No; he meant 83.5V is part of the normal range. 

Inability to charge to 83.0 warrants investigation. 
Lower than 82.0 is very concerning. 
 

On 8/5/2023 at 6:09 PM, Chriull said:

By this higher p count can give batteries a longer live by less burden.

1 hour ago, Mono said:

Isn't this completely independent of whether cells are in series or in parallel? 100W is 100W is 100W, after all. 

Individual cells don't know "power"; only current. 
An EUC drawing 100W from 20s2p is putting only half the current on each cell, compared to 20s1p. Therefore the 20s1p pack is more "stressed" by this 100W, and ages much more quickly. 

And then to compare two theoretical packs of the same capacity, 20s2p vs 40s1p, cell current becomes equal again, for the same 100W motor power. But the 40s pack will be more difficult to keep equalized during its lifetime. Cell condition variation in the 2p pack is "averaged" across pairs of cells; but in the 1p pack, any single cell's problem will stand out, with no help from neighboring cells. 
 

Edited August 18, 2023 by RagingGrandpa

[mhpr262]

22 hours ago, RagingGrandpa said:

and ages much more quickly

I think that depends entirely on the current, how long it flows and how much heat is generated. Unless you draw so much that the tabs burn through, or you draw so much for so long that the battery overheats the amount of current you draw doesnt affect the lifespan of the battery.

[rcgldr]

I just bought an 18XL V2 (spiked pedals, mini-power pads (protrusions at front and back of upper pads), received it on April 25, 2024 , and I used the KingSong app to monitor a full charge with the stock charger. When the stock charger LED turned green, the app showed voltage fluctuate between 84.02 and 84.05 volts, with current mostly at -0.00 amps, and an intermittent pulse of about -0.25 amps every 5 to 10 seconds. I assume this is evidence of the 18XL doing passive cell balancing, reducing current to the pack to near 0 amps, to let the 100 ohm resistors drain the highest voltage cell groups, then intermittently enabling a small current once the highest voltage group drops below some voltage threshold to do a small charge to the entire pack, repeating this cycle as needed to balance the pack. 

On my V8F with the stock charger, once it shuts off current due to some voltage threshold of some cell group, it slowly discharges over the next 8 hours to 82.5 volts before it reenables charging, taking about 20 minutes to reach that voltage threshold where it shuts off charging and repeats the 8 hour 20 minute cycle. The resistors are 1000 ohms versus 18XL (and other KIngSong EUCs) 100 ohms. It's possible that this is some type of balancing that slowly discharges the entire pack, as opposed to the 18XL where the voltage stays above 84 volts while it s apparently balancing the pack. I think this is the point brought up in Wrong Way's video about Inmotion BMS not having passive cell balancing.

I also have an eWheels rapid charger, but it goes into standby and shuts off charging when current transitions below 0.3 amps, which would prevent the 18XL from balancing. What I did for my 18XL was use the eWheels charger to get 18XL to 82 volts, then I switched to the stock charger.

 

Edited April 28 by rcgldr

[Chriull]

14 hours ago, rcgldr said:

I assume this is evidence of the 18XL doing passive cell balancing, reducing current to the pack to near 0 amps, to let the 100 ohm resistors drain the highest voltage cell groups, then intermittently enabling a small current once the highest voltage group drops below some voltage threshold to do a small charge to the entire pack, repeating this cycle as needed to balance the pack. 

Bms charge stop happens once a cell groups voltage exceeds some 4.25V and charging is restarted once this cell groups voltage drops below some 4.19 ... 4.2V. This takes more like many hours to a day to discharge than 5-10 seconds.

These current pulses are more likely some cpu activity on the motherboard (?capacitor recharging to support the cpu?)

14 hours ago, rcgldr said:

also have an eWheels rapid charger, but it goes into standby and shuts off charging when current transitions below 0.3 amps, which would prevent the 18XL from balancing.

That's exactly how li ion battery chargers should behave (according to the cell manufacturers ).Prevent endless trickle charging and allow the important final step of balancing once the charger is disconnected! 

[rcgldr]

8 hours ago, Chriull said:

Bms charge stop happens once a cell groups voltage exceeds some 4.25V and charging is restarted once this cell groups voltage drops below some 4.19 ... 4.2V. This takes more like many hours to a day to discharge than 5-10 seconds.

My main point was that 18XL voltage remained constant, fluctuating between 84.02 to 84.05 volts for 5 or more hours, with the stock charger. 

8 hours ago, Chriull said:

< Charger shuts off once below 0.3 amp

That's exactly how li ion battery chargers should behave (according to the cell manufacturers ).Prevent endless trickle charging and allow the important final step of balancing once the charger is disconnected! 

Passive cell balancing occurs while the charger is outputting voltage and current, not after charger shuts off. Take a look at Wrong Ways' video again:

 

 

Edited April 29 by rcgldr

[Krb73]

Raging Grandpa u seem to know slot I really am new at repairing these euc and I really could use some help

[Chriull]

9 hours ago, rcgldr said:

Passive cell balancing occurs while the charger is outputting voltage and current, not after charger shuts off.

Seems like a wrong way

[rcgldr]

To clarify what my 18XL does: with the stock charger, and monitoring with the KingSong app, it cycles the charging off and on until the pack is charged and balanced. The 18XL BMS has 100 ohm resistors which translates into 0.042 amps if a cell group is at 4.2 volts. From the app, I see voltage at 84.02 to 84.05 volts, current at 0.00 amps, and about every 5 seconds, a brief pulse of 0.25 amps, then back to 0.00 amps, for a net average current less than 0.042 amps, which is low enough for the 100 ohm resistors to drain the cell groups above some upper voltage threshold. I don't know when this cycling starts, but assume it starts when a cell group reaches some upper voltage threshold, or when the pack reaches some overall voltage. If the pack's overall voltage is lower, then the frequency and duration of the current pulses would be less to compensate for the higher current, again so that the net average current is below 0.042 amps. I've read that it is recommended to let the 18XL balance for about 2 1/2 to 3 hours, giving the 18XL enough time to balance and shut down charging.

My V8F has 1000 ohm resistors, and could do something similar, but the pulses would have to be very short or the frequency reduced to about once every 50 seconds for a net average current below 0.0042 amps. However, it doesn't do this. Instead it cycles off once a cell group reaches some upper voltage threshold, then during the next 8 hours, it slowly discharges to 82.6 volts before reenabling charging, taking about 15 minutes before a cell group once again reaches some upper voltage threshold, shutting off charging for another 8 hours. It's unknown if the slow decrease is simply due to the V8F running enough circuitry to communicate with an app, or if it's discharging the higher voltage cell pairs with the 1000 ohm resistors. With 1/3rd of the 18XL pack (20S2P versus 20S6P), but 1/10th of the discharge current, then if it is draining the high voltage cells with the 1000 ohm resistors, then 8 hours might be enough, but the pack ends up at 82.6 volts. Rather than monitor voltage, 8 hours after stock charger led turns green, something like the eWheels rapid charger could be used, since it goes into standby and shuts off once current drops below 0.3 amps and turns the led green, which in turn shuts off the V8F and stops the slow discharge.

Since the eWheels rapid charger shuts off charging when current drops below 0.3 amps, it can't be used for balancing, so I have to use stock charger for balancing. I can use the eWheel rapid charger to charge to 90% and then switch to stock charger.

Edited May 27 by rcgldr

[Knight Rider]

I departed with 100% power on my V11 for a ride of 8.5 miles with a duration of 41 minutes and finished with 88% my top speed was 32 MPH but on average was doing 27 MPH. On my route I did go up hill a little bit and came back going down hill. At the end of my ride both batteries had 81 volts in them. I had already crossed 1088 miles in total with the wheel so far. Is my wheel still good or should I be concerned about getting a new one?

Edited May 25 by Knight Rider

[rcgldr]

On 5/25/2024 at 12:51 PM, Knight Rider said:

8.5 miles with a duration of 41 minutes

That is an average speed of 12.4 mph. On my new 18XLV2, voltage was 74 volts after about 50 miles, average speed of 14 to 15 mph. Update - after a full charge (84 volts), I rode 7.6 miles in 30 minutes, average speed 15.2 mph mild inclines and declines and a bit windy, voltage after ride was 82 volts.

On 5/25/2024 at 12:51 PM, Knight Rider said:

1088 miles

Shouldn't be an issue, riders have ridden much further than that without having to replace anything. Suspension components will need regular maintenance, mostly cleaning and lubing, plus maintaining air pressure in the suspension. 

Edited May 27 by rcgldr

[Knight Rider]

On 5/26/2024 at 3:18 AM, rcgldr said:

That is an average speed of 12.4 mph. On my new 18XLV2, voltage was 74 volts after about 50 miles, average speed of 14 to 15 mph. Update - after a full charge (84 volts), I rode 7.6 miles in 30 minutes, average speed 15.2 mph mild inclines and declines and a bit windy, voltage after ride was 82 volts.

Well that's 41 minutes of the wheel being on not necessarily 41 minutes of riding

[kintips]

On 4/29/2024 at 3:54 AM, rcgldr said:

My main point was that 18XL voltage remained constant, fluctuating between 84.02 to 84.05 volts for 5 or more hours, with the stock charger. 

Passive cell balancing occurs while the charger is outputting voltage and current, not after charger shuts off. Take a look at Wrong Ways' video again:

 

 

You are right. As well wrongway is correct. I had v5f v8f and v12 all had same issue. The bms cells doesnt have passive cell balancing (on older models). All my wheels died at 250km with please repair or not getting full range you can watch my videos on it

https://youtu.be/EFEFCG-rBcQ?si=LfD4hZWfCfkd_Pvo

 

https://youtu.be/T1T7NZyQsq0?si=n2BJpmCBLKzBga3n

[rcgldr]

On 6/21/2024 at 10:04 AM, Cam said:

AFAIK depending on design passive balancing can happen after the charger is off; as bleed resistors drain the higher voltage cell groups. On my Sherman OG a thermal camera shows heat on the BMS just where those resistors are for a few hours after disconnecting the charger.

In the case of the V8F, V10F, and maybe other Inmotion EUCs, what might be bleed resistors are 1,000 ohm, which translates into a current of 0.0042 amps. At that small of a current, it would take a long time to balance. As I posted earlier, on my V8F, once a cell group reaches maximum voltage, it shuts off charging and slowly discharges over the next 8 hours to 82.5 volts before enabling charging again. I don't know if this slow discharge is just due to keeping my V8F awake enough to communicate with the app, and light the blue LEDS that indicate battery charge, or if those 1000 ohm resistors are part of that slow discharge. My 18XL uses 100 ohm bleed resistors which translates into 0.042 amps (10 times as much as my V8F), and its cycle period is about 5 seconds (not 8 hours), a short burst of current about every 5 seconds that keeps the average current below the 0.042 amps that the bleed resistors drain to balance the pack. KingSong recommends letting the 18XL balance for 2 to 3 hours. Note that the 18XL will shut off charging once the pack is balanced to avoid the issue of continuous trickle charging of the pack, so only a fraction of that 2 to 3 hours is used for a pack that is nearly balanced.

[Rotator]

Because I had a problem with my left inmotion v12 battery, I needed to dissasemble it and replace a defective cell.

There is no bleeding resistors at all, but anyway, I decided to test if is there any passive balancing system (some BMS chips can do a low current balance by themselves).

In short, NO, there is NO ANY balance system in V12 battery that I could prove. I pushed a cell series above 4.25v and I could not meassure any milliampere drained by the bms.

The BMS charge section was automatically disconnected as soon as any cell series goes above 4.2, but this does not help with getting all cell series balanced.

For this reason, I will add a passive balance board inside the battery, since there is room for it.

Edited July 11 by Rotator

[kintips]

12 hours ago, Rotator said:

Because I had a problem with my left inmotion v12 battery, I needed to dissasemble it and replace a defective cell.

There is no bleeding resistors at all, but anyway, I decided to test if is there any passive balancing system (some BMS chips can do a low current balance by themselves).

In short, NO, there is NO ANY balance system in V12 battery that I could prove. I pushed a cell series above 4.25v and I could not meassure any milliampere drained by the bms.

The BMS charge section was automatically disconnected as soon as any cell series goes above 4.2, but this does not help with getting all cell series balanced.

For this reason, I will add a passive balance board inside the battery, since there is room for it.

I had a hunch, this is why my v12ht battery needed recalibrating after a while. Thanks for confirming my hunch.

[RagingGrandpa]

On 7/11/2024 at 4:59 AM, Rotator said:

inmotion v12 battery
There is no bleeding resistors at all

Umm... here they are: 

On 3/10/2023 at 9:17 AM, RagingGrandpa said:

V12's BMS, with its distinct array of 24 bleed resistors:

Quote

 

[rcgldr]

On 3/10/2023 at 6:17 AM, RagingGrandpa said:

V12's BMS, with its even more distinct array of 24 bleed resistors:

What is the resistance of those resistors? If you run the app when charging, how long does the voltage show 84 volts or slightly above, before the V12 shuts off charging due to overvoltage? Again, my 18XL partially shuts off charging before overvoltage occurs, showing 84.02 to 84.05 volts (on KingSong app) switching to intermittent bursts of current about -0.25 amps every 5 seconds or so, in order for the average charge current to be less than the 0.042 amps drained by the 100 ohm bleeding resistors, avoiding an overvoltage situation. According to KingSong, this balancing can go on for up to 3 hours depending on initial pack balance. I've seen it balancing the pack for at least 30 minutes (on the initial charge). Once the pack is balanced, the 18XL fully shuts off charging. If the V12 resistors are the same 1000 ohm resistors seen on V10F and V8F, then it would take 10 times as long to balance a pack, assuming that there is any balancing. From what I've read, the V12 doesn't have similar logic to prevent over-voltage and instead just shuts off all charging once a cell group reaches overvoltage. There's no way to know if there is any balancing while the pack slowly discharges, which is about 8 hour on my V8F before voltage drops to 82.5 volts and the V8F reenables charging for about 15 to 20 minutes before reaching overvoltage yet again, shutting off charging, repeating the cycle every 8.3 hours or so.

Edited July 18 by rcgldr

[samzzzz]

On 18.07.2024 at 06:06, rcgldr said:

Каково сопротивление этих резисторов? Если вы запустите приложение во время зарядки, как долго напряжение будет показывать 84 вольта или чуть выше, прежде чем V12 прекратит зарядку из-за перенапряжения? Опять же, мой 18XL частично отключает зарядку перед возникновением перенапряжения, показывая напряжение от 84,02 до 84,05 вольт (в приложении KingSong), переключаясь на периодические скачки тока около -0,25 ампер каждые 5 секунд или около того, чтобы средний ток заряда был меньше 0,042 ампер, потребляемых выпускными резисторами 100 Ом, что позволяет избежать ситуации с перенапряжением. Согласно KingSong, такая балансировка может продолжаться до 3 часов в зависимости от начального баланса аккумулятора. Я видел, как аккумулятор балансировался не менее 30 минут (при первоначальной зарядке). После балансировки аккумулятора зарядка 18XL полностью прекращается. Если резисторы V12 совпадают с резисторами 1000 Ом, используемыми в V10F и V8F, то для балансировки блока потребуется в 10 раз больше времени, при условии, что балансировка вообще есть. Из того, что я прочитал, у V12 нет аналогичной логики предотвращения перенапряжения, и вместо этого он просто отключает всю зарядку, как только группа элементов достигает перенапряжения. Нет способа узнать, есть ли какая-либо балансировка, пока аккумулятор медленно разряжается, что составляет около 8 часов на моем V8F, прежде чем напряжение упадет до 82,5 вольт, и V8F возобновит зарядку примерно на 15-20 минут, прежде чем снова достигнет перенапряжения, отключит зарядку, повторяя цикл каждые 8,3 часа или около того.

Good afternoon,tell me I have the same problem with one v12 battery,what does your problem look like, I have an imbalance between 1 volt batteries

[kintips]

5 hours ago, samzzzz said:

Good afternoon,tell me I have the same problem with one v12 battery,what does your problem look like, I have an imbalance between 1 volt batteries

I got inmotion to remote calibrate it.

[samzzzz]

8 minutes ago, kintips said:

Я подключил inmotion для удаленной калибровки.

remotely, the Chinese did the calibration, at 101.3 volts, only to discharge up to 50%, the wheel lifts the pedals, and through the application asks for calibration, and when fully charged, an error hangs, and the charge in the application is 101.4 and 100.4 volts

[rcgldr]

8 hours ago, kintips said:

I got Inmotion to remote calibrate it.

Inmotion did a remote "calibration" on my V8F, but I don't think it's an actual calibration. They tell you to fully charge the battery pack, then email them to do the online "calibration" which I think just sets the transmitted voltage that you see on an app to 84 volts despite what the actual pack voltage is. Essentially it is just a voltage correction meant to display 84 volts at whatever the pack voltage was when they did the online "calibration".

Edited July 21 by rcgldr

[Mono]

On 4/29/2024 at 11:54 AM, rcgldr said:

Passive cell balancing occurs while the charger is outputting voltage and current, not after charger shuts off. Take a look at Wrong Ways' video again:

LOL, pointing to Wrong Way for educating @Chriull on batteries is quite a stretch 

[rcgldr]

6 hours ago, Mono said:

LOL, pointing to Wrong Way for educating @Chriull on batteries is quite a stretch 

It was Wrong Way's friend Serg (a battery | BMS technical person for both e-bikes and EUCs) that explained the issue to Wrong Way. Serg doesn't speak English well (they are both Polish), so Wrong Way does most of the talking in the two videos about this.

As far as Wrong Way usage of the term active balancing, what he meant was the balancing can occur at lower voltages and not while connected to a charger. I don't know if the "active" balancing on the 3 EUCs he mentioned only drain the higher voltage cell groups, as opposed to using higher voltage cells to charge lower voltage cells, which would require even more specialized circuitry, and I'm not sure if it would end up being significantly better than just the small amount of discharge needed to balance cells between charge cycles.

Kintips had a battery failure due to imbalance after only 250 km == 150 miles on his V8F. I've been lucky, I've got 1550 miles on my V8F, and lost about .6 volts total voltage on my battery pack (84 volts down to 83.4 volts since August 2021 and 1550 miles).

Edited July 23 by rcgldr

[Mono]

5 hours ago, rcgldr said:

Kintips had a battery failure due to imbalance after only 250 km == 150 miles on his V8F.

5 hours ago, rcgldr said:

I've been lucky, I've got 1550 miles on my V8F, and lost about .6 volts total voltage on my battery pack

The V8-series wheels have been sold in the order of 100,000 times, so it seems that many people "got lucky".

On 6/21/2024 at 6:25 PM, kintips said:

I had v5f v8f and v12 all had same issue.

That's quite a coincidence. What happened with the V5F after the factory reset?

Edited July 23 by Mono