Is Wrongway right about V8S BMS?

[rcgldr]

I have 1062 miles on my V8F, which I got back in August 2021, about 19 months old. 100% charge is down from 83.6 volts to 83.4 volts.

 

Edited March 10, 2023 by rcgldr

[v8nice]

Unbalancing start...

now you no longer have any doubts about what I wrote. There is no balance system at inmotion before v13. There is no point in leaving the branch for a long time after going green. 1 hour more just to let the cells be well filled, as best as possible without balancer... All inmotion are condemned to be thrown in the trash or passed by a technician. We could also talk about inmotion chargers which are also crap?

[mrelwood]

55 minutes ago, v8nice said:

There is no balance system at inmotion before v13.

So, you have examined old V5 and V8 batteries, and because the cells are not well balanced, you are certain that they, V10, V11, and V12 series of wheels don’t have a balancing feature? Your definition of proof is humorous.

A comment in WrongWay’s YT video said it well: Everybody with even the slightest knowledge of electronics and batteries knows that series battery packs must have a balancing feature.

I fully agree. Otherwise there would be a huge amount of preliminary battery failures. But there aren’t.

[rcgldr]

40 minutes ago, v8nice said:

1 hour more just to let the cells be well filled, as best as possible without balancer.

1 hour more won't help, it will actually drain the pack a bit. Inmotion BMS will stop all charging once any parallel block of cells reaches maximum voltage. In the case of my V8F, after it stops charging, it continues to draw a small amount of current for bluetooth and the blue battery charge leds, so if I leave the stock charger running, what I see is decreasing voltage on EUC World. I have to disconnect the stock charger for the V8F to shutdown. My rapid charger shuts off at 300 ma | 83.4 volts, so it can be used without monitoring and the V8F will shut down since the rapid charger shuts down. Back in December 2022, after the rapid charger shut down, I was able to use the stock charger to get the pack up to 83.6 volts. When I tried this yesterday, it didn't help. I tried doing a short ride and charging again, but it didn't make any difference.

 

 

 

[rcgldr]

3 minutes ago, mrelwood said:

So, you have examined old V5 and V8 batteries, and because the cells are not well balanced, you are certain that they, V10, V11, and V12 series of wheels don’t have a balancing feature? Your definition of proof is humorous.

A comment in WrongWay’s YT video said it well: Everybody with even the slightest knowledge of electronics and batteries knows that series battery packs must have a balancing feature.

I fully agree. Otherwise there would be a huge amount of preliminary battery failures. But there aren’t.

My V8F once charged to 83.7 volts, now it maxes out at 83.4 volts. From what I've read, although capacity of the battery packs will decline as they age, the peak voltage should remain the same.

[mrelwood]

1 minute ago, rcgldr said:

My V8F once charged to 83.7 volts, now it maxes out at 83.4 volts. From what I've read, although capacity of the battery packs will decline as they age, the peak voltage should remain the same.

There are several possible reasons for a declining max voltage, all presented in this thread several times. Bad balance is one of them, but only one of them.

[rcgldr]

36 minutes ago, mrelwood said:

you are certain that they, V10, V11, and V12 series of wheels don’t have a balancing feature?

The service guy in Wrong Ways video explains the issue using a V10 (or V10F) BMS as an example, and Wrong Way holds up a V11 BMS explaining it's also doesn't have the bleeding resistors. He explains that it just shuts off the charge to all cells once any parallel group of cells reaches max (4.2) voltage. What's missing are the bleeding resistors that would hold or drain voltage from groups of cells that have reached maximum voltage while the remaining groups continue to charge until all groups are fully charge and equal in voltage.

It is possible that bleeding resistors are included inside of logic chips, but I wonder if heat dissipation would be an issue, which is why in most (if not all) cases, external bleeding resistors are used.

Again I emailed service@imscv.com about passive cell balancing and they replied that the V8F doesn't have passive cell balancing. Wrong Way got the same response, but I'm not sure who he had contacted.

I sent service@imscv.com another email, and they replied that they wanted me to fully charge my V8F with the stock charger, then contact them and they would do some type of online calibration. I replied back asking what that online calibration would involve and what it would accomplish. I'll update this thread when I get a response.

Edited March 10, 2023 by rcgldr

[supercurio]

Since

• Inmotion says there's no balancing
• looking at the BMS shows no balancing circuit (including V11)

It seems fair to say that there's no balancing unless proven otherwise @mrelwood

Someone with a V11 or V12 pack open could certainly unbalance a few cell group and see if that gets balanced out by the BMS, in order to get the topic moving forward again with more knowledge and experimentation.
All the evidence so far points towards no balancing.

Edited March 10, 2023 by supercurio

[mrelwood]

The arguments have been provided before, but here we go again:

52 minutes ago, supercurio said:

Since

• Inmotion says there's no balancing

To me they said that there is. I believe this has been a language issue. I described what balancing does, and asked if the V11 has one. Answer was yes.

52 minutes ago, supercurio said:

• looking at the BMS shows no balancing circuit (including V11)

Yes, there aren’t the resistors in a single row. There are however similarly sized resistors all over the BMS. In addition there are several ICs that I would guess would be able to provide 50-100mA of dissipation.

52 minutes ago, supercurio said:

It seems fair to say that there's no balancing unless proven otherwise @mrelwood

I would look at it the other way around: That there is reason to believe that balancing exists unless proven otherwise. Reasons being, in addition to above:

- Several V10F wheels that were not charging to full were salvaged by looping a few times between 80-100% SoC. If there were no balancing, how could this happen?

- My V11 cells were all within 0.01V, the smallest my meter can measure. This was after 4000km. The probability of having 80 perfectly matched cells is just too small.

- The amount of battery aging issues doesn’t seem to be any larger with Inmotion than other manufacturers. If Inmotions didn’t balance, we’d have huge amounts of battery failures after a few thousand km. Either Inmotions balance the cells well enough, or balancing is useless. And I know for the latter to be incorrect.

52 minutes ago, supercurio said:

All the evidence so far points towards no balancing.

This post has several pieces of evidence proving otherwise.

[jimjam.nyc]

Weather there is balancing or not in any wheels, wrong way wouldn't be the authority I follow on advice for buying wheels. The guy changes his opinion on things constantly. 

Entertainment wise I think he is great and love his videos, but He seems to hold grudges alot. 

Would take riding advice from him all day everyday. But other than that I wouldn't think too much about what he sais. He ditched begode 4 times after getting his clicks at their expense too.

At the end of the day all of these wheels have issues and are overpriced at this stage.  Inmotion is no different than the rest of them. 

[rcgldr]

2 hours ago, mrelwood said:

- Several V10F wheels that were not charging to full were salvaged by looping a few times between 80-100% SoC. If there were no balancing, how could this happen?

i tried a bit of that yesterday, but not as much. I charged, rode 1/2 mile, charged again, rode another 1/2 mile, and charged again. Keep in mind that it's a V8F, with not much range. I did see an increase from 83.4 to 83.5 volts for 15 seconds or so, but it then dropped back down to 83.4 volts, and if I left the stock charger connected, the voltage kept decreasing (blue tooth and the blue led battery SOC lights).

If there is passive cell balancing, my guess is the bleeding resistance is too high to actually hold or reduce voltage of a cell group, and the voltage continues to increase, but at slower rate, reaching the charging cutoff voltage which stops the entire charging process before the other cell groups get fully charged. 

Next time I charge to 100%, I can try more cycles, and more than 1/2 mile rides between. There's no point in discharging the highest voltage group below the bleeding resistor threshold. What is needed is to cycle the highest voltage groups between the bleeding resistor threshold and the charge cutoff threshold, where the lower voltage groups catch up a bit with each cycle.

Edited March 10, 2023 by rcgldr

[jimjam.nyc]

Most of my battery powered devices drop the first volt or two very quickly. Even if I get 100.4 v max charge on my wheel it's down to 99, 98 very very quickly. My range has not suffered at all.

There seems to be too many experts in this community. I am sure they are all knowledgeable. But you will get 100 different opinions on this very topic.  A while ago I stopped being ocd on the tiny details and began to enjoy riding more. I noticed much of the obsessing over everything was for nothing.

That being said you should keep an eye on your batteries and take actual abnormalities seriously. I check my pack balances all the time and are way more concerned about that, than getting the absolute 100.Whatever every charge cycle.

On topic I have owned and slapped miles on a few inmotion wheels now. Never had a pack go out of balance. So passive cell balancing or not, things seem to be fine for me. Guess I am either too lucky, or maybe it just doesn't matter.. bad batteries and failures happen either way. Maybe just ride..

Edited March 10, 2023 by jimjam.nyc
Spelling

[Chriull]

18 minutes ago, rcgldr said:

Next time I charge to 100%, I can try more cycles, and more than 1/2 mile rides between.

To try balancing riding inbetween the cycles is not necessary. Better to leave the wheel for 1/2 to 2 hour so the bleeding resistors can do their work.

Then charge again until green light shows.

20 minutes ago, rcgldr said:

did see an increase from 83.4 to 83.5 volts for 15 seconds or so, but it then dropped back down to 83.4 volts, and if I left the stock charger connected, the voltage kept decreasing

Decreasing voltage shows that the charging input was cut off. Afair V8 had no motherboard charge control like "newer" wheels.

So it should be the bms cutting off, showing cell imbalance!?

Was final reported battery voltage higher before? Did no load charger voltage change?

[RagingGrandpa]

I'm detecting a trend of youtube sensationalism from Adam...

Regarding Inmotion's cell balancing, my thoughts here: 
https://forum.electricunicycle.org/topic/32080-do-inmotion-battery-packs-perform-cell-balancing-yes/

But really, does this matter to anyone besides the manufacturers? 
There is absolutely no practical action that the end-user could take, to change how their BMS works.

Are ya'll really suggesting "ban every Inmotion EUC before V13?" Really?  

[rcgldr]

45 minutes ago, Chriull said:

To try balancing riding in between the cycles is not necessary. Better to leave the wheel for 1/2 to 2 hour so the bleeding resistors can do their work.

If my theory is correct, balancing only occurs when the higher voltage cell groups are between bleeding resistor enabled voltage and charge cut off voltage. Once the charge cut off voltage is reached on any cell group, charging is disabled for all cell groups. So the higher voltage cell groups need to be cycled between bleeding resistor enabled voltage and charge cut off voltage, while the remaining cell groups catch up a bit with each cycle.

There is no active balancing that would drain voltage from higher voltage groups and use that to charge lower voltage groups. A charger needs to be connected, and the charging not cutoff due to one of the groups reaching the charge cutoff voltage.

If the bleeding resistance was low enough to drain a tiny bit of voltage from a cell group, that cell group would decrease in voltage while the other cell groups increase in voltage. Eventually all the cell groups would reach the bleeding resistance voltage threshold. 

45 minutes ago, Chriull said:

V8 Decreasing voltage shows that the charging input was cut off.  Was final reported battery voltage higher before? Did no load charger voltage change?

I have a V8F. Stock charger continues to output voltage even when LED turns green. The V8F stops the charging, but uses the current from the charger for blue tooth and the blue SOC leds. If I leave the charger connected, voltage slowly decreases, due to the small amount of current being used.  If I disconnect the charger, the V8F shuts down and there's no voltage decrease.

Edited March 10, 2023 by rcgldr

[Chriull]

14 minutes ago, rcgldr said:

If my theory is correct, balancing only occurs when the higher voltage cell groups are between bleeding resistor enabled voltage and charge cut off voltage. Once the charge cut off voltage is reached on any cell group, charging is disabled for all cell groups. So the higher voltage cell groups need to be cycled between bleeding resistor enabled voltage and charge cut off voltage, while the remaining cell groups catch up a bit with each cycle.

There is no active balancing that would drain voltage from higher voltage groups and use that to charge lower voltage groups. A charger needs to be connected, and the charging not cutoff due to one of the groups reaching the charge cutoff voltage.

If the bleeding resistance was low enough to drain a tiny bit of voltage from a cell group, that cell group would decrease in voltage while the other cell groups increase in voltage. Eventually all the cell groups would reach the bleeding resistance voltage threshold. 

Or the one higher voltage cell that caused charge input cutoff still has the bleeding resistor enabled and gets discharged to some ~4.2V.

If single cell cutoff voltage is somewhere around 4.25V the other cells get charged during the next cycle a bit more than this 0.05V difference, as the highest voltage cell has the bleeding resistor enabled.

Ir a little be less, since the high voltage cell should be the weakest cell - depends which of this two effects is stronger.

So with each cycle the lower voltage cell near by something roughly around 0.05V. Times 19 this should be almost up to a volt per cycle.

14 minutes ago, rcgldr said:

I have a V8F. Stock charger continues to output voltage even when LED turns green. The V8F stops the charging, but uses the current from the charger for blue tooth and the blue SOC leds. If I leave the charger connected, voltage slowly decreases, due to the small amount of current being used.  If I disconnect the charger, the V8F shuts down and there's no voltage decrease.

The question is if the mainboard stops charging once some total voltage is reached and then drains the battery for its own operation.

Or there is cell imbalance and the bms cuts of charging. And the motherboard knows nothing and keeps draining the battery...

[mrelwood]

Found it in an old conversation:

[rcgldr]

4 hours ago, Chriull said:

The question is if the mainboard stops charging once some total voltage is reached and then drains the battery for its own operation.

Or there is cell imbalance and the bms cuts of charging. And the motherboard knows nothing and keeps draining the battery...

On my V8F, the charging stopped at 83.6 volts 2 months ago, and it now stops at 83.4 volts, so it's not total voltage. 

 

 

[lagger]

9 minutes ago, rcgldr said:

On my V8F, the charging stopped at 83.6 volts 2 months ago, and it now stops at 83.4 volts, so it's not total voltage. 

 

 

Does it stop because euc cuts it off or it stops because thats maximm charger voltage. I have heard that some people were playing with potentiometer to tweak output voltage of the charger.

[rcgldr]

22 minutes ago, lagger said:

Does it stop because euc cuts it off or it stops because thats maximm charger voltage. I have heard that some people were playing with potentiometer to tweak output voltage of the charger.

It stops because my V8F stops charging. I've never messed with the charger voltage.

[v8nice]

the inmotion charger (v5, v8, v10) are bad, often voltage variations, which does not help to maintain a battery in good condition ... just like the motherboard which does not know how to read the battery voltage correctly sometimes (display 85v instead of 84v ....) Adam does not like begode too much because of the quality of manufacture, but he admits that even at Begode there is a balancer on the bms.

[Chriull]

12 hours ago, rcgldr said:

On my V8F, the charging stopped at 83.6 volts 2 months ago, and it now stops at 83.4 volts, so it's not total voltage. 

Your posts are unfortionately scattered within this topic.

But your "charge cycling" not increasing final charge voltage and the sudden lower final charge voltage 2 months ago means somethings wrong.

[rcgldr]

5 hours ago, Chriull said:

But your "charge cycling" not increasing final charge voltage and the sudden lower final charge voltage 2 months ago means somethings wrong.

The lower final charge 2 months ago wasn't sudden, the decrease from 83.6 to 83.0 occurred over a 2 hours period while connected to the charger, which meant the V8F had stopped the charging, but continued to communicate to EUC World and keep the blue SOC leds on, and related circuitry.

The cycling 2 months ago brought voltage back up to 83.6 volts, but it had reached 83.6 before any cycling. It's been raining, but when the rain stops, I'll try a few charge | short ride | charge | ... cycles to see it that makes any difference. 

The key point here is the V8F is shutting off the charging, which is most likely due to a pair of cells reaching some maximum voltage, which in turn would mean that if there are bleeding resistors, the resistance is too high to hold or lower voltage of that pair of cells to give the other pairs of cells time to continue charging to the bleeding resistor voltage threshold.

Edited March 11, 2023 by rcgldr

[mrelwood]

In this video I'm analysing the rumor with superficial circuit analysis on V8, V8F, V10F, and V11, battery measurements on a 4000km old V11, experience with V10F charging behavior, discussion with an Inmotion engineer, and other arguments:

 

[rcgldr]

15 hours ago, mrelwood said:

In this video I'm analyzing the rumor with superficial circuit analysis on V8, V8F, V10F, and V11, battery measurements on a 4000km old V11, experience with V10F charging behavior, discussion with an Inmotion engineer, and other arguments. ... Wrong Way's video - no balancing

Wrong Way is basing his opinion on two factors: one is a reply from Inmotion that there is no passive cell balancing. I got the same reply, twice, from service@imscv.com. The other factor is more important, what has been observed is that V10|V10F BMS halted all charging once any group of parallel cells reached some maximum voltage, before balancing completed. The tech guy observed the halted charging on a V10|V10F BMS, but apparently didn't check to see if there was any balancing activity.

My opinion is that there is passive cell balancing, but the bleeding resistance is too high (too many ohms) to drain cells once they reach the balancing voltage threshold, only slowing down the rate of increase, allowing the voltage to continue to increase and halt all charging before balancing has completed. Mrelwood's video mentions there are 1 k ohm resistors on the Inmotion V11 BMS. What is the resistance of the Begode resistors? Apparently the resistance of the bleeding resistors on KingSong | Begode | Veteran BMS is low enough to drain voltage from any group of cells reaching some maximum voltage along with logic to drain those groups back to balancing voltage or a bit below, so that a single 100% | balancing charge would balance a pack (all groups charged to balancing voltage) no matter how imbalanced it was. The Inmotion BMS issue may be due to the balancing logic chips not being able to dissipate heat as much as the other BMS designs, restricting the bleeding resistors to 1 k ohms.

This would explain why v8nice measured the voltages on a V8F, 5 pairs at ~4.2 volts, 15 pairs at ~4.15 volts. It would also explain while leaving a charger connected to my V8F, I saw a peak voltage of 83.6 volts, followed by a gradual decrease in voltage to 83.0 volts over a 2 hour charge: the V8F BMS had halted the charging, but continued to draw a small amount of power for blue tooth and other circuitry.

https://forum.electricunicycle.org/topic/28209-is-wrongway-right-about-v8s-bms/?do=findComment&comment=457379

I will try mrelwood's suggestion of doing multiple full charge | partial discharge | full charge | ... cycles to see if it increases overall voltage on my V8F battery pack back to 83.6 or 83.7 volts.

Edited March 14, 2023 by rcgldr