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Charging: Are current Begode / Extremebull EUCs allowing battery balancing to happen?


Cam

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On all other EUCs I have had voltage will taper out progressively at end of charge. The stock charger will never stop on its own, allowing for saturation charge at the end of the Constant Voltage phase.

The Commander pro stops charge while the voltage is still rising, making me think that it have not done saturation charge, not allowed groups to cut for balance during charge, nor for the voltage to be high enough for balancing bleed to happen.

The charger is also pulling too much power (120W) from the wall (before it suddenly stops) for typical li-ion charging to be done.

If this normal behavior for Begode / Extremebull EUCs?

edit: I see discussions about upper voltage and drain, but would have thought balancing was the more important aspect as it could lead to cell failure and fire.

 

With stock charger: (same behavior is seen with a third party charger except upper voltage is 133.7V)

IMG_1071.thumb.jpg.209e54979e470c163f2c5
 

All other EUCs I have had have this type of voltage curve: (the bump is a charger swap)

IMG_1029.thumb.jpg.dcbfea412ad073f41c575

 

Edited by Cam
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  • Cam changed the title to Charging: Are current Begode / Extremebull EUCs allowing battery balancing to happen?
12 hours ago, Cam said:

The Commander pro stops charge while the voltage is still rising,

Seems like (one of the packs) is out of balance and cutting charge prematurely off due to single cell overvoltage.

12 hours ago, Cam said:

making me think that it have not done saturation charge, not allowed groups to cut for balance during charge, nor for the voltage to be high enough for balancing bleed to happen.

Exactly. As your charge graph shows your battery is just on the change from cc to cv stage when it stops  charging.

12 hours ago, Cam said:

edit: I see discussions about upper voltage and drain, but would have thought balancing was the more important aspect as it could lead to cell failure and fire.

In unbalanced packs the weakest cell(s) get stressed most with each charge and (lower) discharge until the are dead. Then the risk to start a fire is highly increased.

As you have not shown single cell (group) voltages i assume the commander pro does not report those?

So as next step you could try to charge each of the commander pro's battery pack on it's own. And before this check that the chargers no load voltage is not too high.

Likely it's just one pack out of balance stopping charge for all packs.

In case you can by this identify one pack which stops charging prematurely be hesitant to connect the packs with different voltages together again - high currents can lead easily to transform connectors to flying molten metal blobs...

With a bit of good luck some charge and _rest_ cycles can balance such an out of balance pack again.

As @Rawnei managed to balance his packs again just with ?one or two? such cycles and adjusting his charger. This whole process can be read in the lynx megatopic starting from his post about here and following posts:

 

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Posted (edited)

Thank you for the reply @Chriull.

3 hours ago, Chriull said:

As you have not shown single cell (group) voltages i assume the commander pro does not report those?

So as next step you could try to charge each of the commander pro's battery pack on it's own. And before this check that the chargers no load voltage is not too high.

Yes no report on individual cells as the EBCP BMS doesn't monitor those.
I will measure the battery packs separately and report back.
As for charger no-load it should be OK, stock charger is a bit lower than my other brand 10A charger
(Apparently current BG EUCs have their voltage a bit low, which doesn't sound good for balancing, but maybe the BMS take it into account with a lower bleed threshold?)

3 hours ago, Chriull said:

In case you can by this identify one pack which stops charging prematurely be hesitant to connect the packs with different voltages together again - high currents can lead easily to transform connectors to flying molten metal blobs...

With a bit of good luck some charge and _rest_ cycles can balance such an out of balance pack again.

Thanks, yes I will try that if needed.

The packs being in series (2x) and parallel (2x) (AFAIK, them being 67,2V packs (?) ) I won't be able to charge them via the EUC (I suppose?), but will need to get my hands on a 67,2V changer and the right connector.

Can anyone confirm this?

Also: if the packs packs are in series of 2x, is there anything to be done before disconnecting them?

Edited by Cam
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Posted (edited)

Actually I see Marty charging them separately with the stock charger, I will look closer at what voltage they are supposed to be.

Will find out when measuring them. I suppose disconnecting the motherboard from the power distribution board, then the packs should do..

edit: If the packs are 32S2P ("134.4V" each) should it be possible to charge them one by one via the EUC by disconnecting the other 3 battery packs? That would save me a month of waiting for the right connectors (to make an adapter between charger and battery pack) to be delivered.

edit: They are 16S packs.

Edited by Cam
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2 hours ago, Cam said:

I will measure the battery packs separately and report back.

The two 2 packs in series will have the same voltage, as the are parallel. Differences will only show up after separate charging.

The single packs will show some differences, but should be hard to draw conclusions from this.

Theoretically this packs in series could have overall balancing as some bms can be connected - no idea if this is done here. Or they use some kind of this charge control boards like with ?begode master? which drains batteries...

Just watched @Marty Backe's video you linked - so the ebcp has this  *** power distribution board, too.

This could be the sole reason for your premature charge cut off preventing balancing of the cells.

I assume you are aware of the consequences of having the voltage live on the charge plug? ( Marty's second solution) The mentioned follow up video is already out to see solution one?

So best to not mess with separate charging and first try direct charging - seems than normal cv stage should happen. Maybe one, two cycles are needed to balance the packs (edit: if out of balance at all)

2 hours ago, Cam said:

As for charger no-load it should be OK, stock charger is a bit lower than my other brand 10A charger
(Apparently current BG EUCs have their voltage a bit low, which doesn't sound good for balancing, but maybe the BMS take it into account with a lower bleed threshold?)

Without the bms reporting it's own measured voltage, which is the absolute base for the relevant thresholds it is all very relative. The mainboard reported voltage is quite irrelevant (beside the wheels overvoltage warning) and was often not too accurate.

The chargers voltage beeing just a _bit_ low is fine and does not hinder balancing. I'd personally prefer a bit to low than a bit too high.

Edited by Chriull
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Posted (edited)
6 minutes ago, Chriull said:

*** power distribution board

Exactly, very annoying.
Its difficult enough to watch out for an unsafe battery with so many cells in serie, adding a board that both drains voltage, cuts at various points without explanation, make an imbalance worse but not allowing balancing..

(This is also the reason I titled the thread "Current Begode / EB" because most of them have it, and do end up with a rather low end voltage..)

I was about to open it now, at least we'll have pack voltage..

(thank you for the rest of the reply as well, getting back on it later)

Edited by Cam
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I don't fully understand the original post but one idea came to mind.

Maybe this wheel has very powerful bleed resistors so that when enough of them are on, you get a proper voltage difference that later goes away. 

The question I have is why it settles at 132.6v. 

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Posted (edited)
2 hours ago, Chriull said:

This could be the sole reason for your premature charge cut off preventing balancing of the cells.

I assume you are aware of the consequences of having the voltage live on the charge plug? ( Marty's second solution) The mentioned follow up video is already out to see solution one?

So best to not mess with separate charging and first try direct charging - seems than normal cv stage should happen. Maybe one, two cycles are needed to balance the packs.

(Correction: I mistook a video of Martys for something it wasn't, so rewriting the message and putting the old as spoiler.)

I measured the battery packs separately and two where 57,2V and two 57,3V. (about 50% SOC).

So

1: They are four 67,2V battery packs (so I suppose 2x2 put in series by the power distribution board)

2: There is a 0,1V mismatch, probably by pair (each "side cover").

I had thought I had to charge them directly with 67,2V, one at a time. Is them being in series (later on?) an issue?
Martys video bypasses the distribution board limit by charging via the cable that normally goes to the motherboard.
The intention isn't to balance, so all packs are done at the same time.
I would have thought doing a pair at a time would be better for balancing (or even better, individually), however it might upset something in the distribution board? Should I just try Martys approach and bet on the CV phase (repeated) to do the balancing?

 

Spoiler

I measured the battery packs separately and two where 57,2V and two 57,3V. (about 50% SOC). I need a more precise multimeter.

So
1: They are four 67,2V battery packs (so I suppose 2x2 put in series by the power distribution board) different from Martys EBCPs which had 134V packs. No information is given about this, how practical. Someone who wanted to charge them directly with the stock charger would immediately over-volt them. Wrong distribution board would also result in very bad things.

2: There is a 0,1V mismatch on one of the packs. I will have to get my hands on a 16S charger and connectors to make an adapter to try and balance them separately. Very impractical when a 134V pack might have been charged alone by the EUC.

Martys solution: Yes I'm aware, thank you for the reminder. I hate hot plugs and the whole Begode / EB approach in general. The only reason I got this EUC was because the ShermanS was way out of my budget.

Question: The voltage mismatch corresponds to right and left side packs. This would tend to indicate that they are the ones in series. If I can confirm that these are the ones in series, could I try charging them pair by pair? Or should I rather wait for the possibility to do them individually?

edit: another difference with Martys EBCP is that mine has a white cable together with the red and black cables that go to the batteries. I suppose this is some sort of communication cable (it's thick like the power cables though), possibly for the series? I hope this won't make more complications.

edit: CORRECTION: Marty wasn't measuring the battery packs directly, but the output from the distribution board. This changes what I have said previously. He also charges the batteries, not one by one, but all together, using the port that normally powers the motherboard. 

So the battery packs are maybe not 32S2P on his, but 16S4P like on mine. 

Sorry!

 

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1 hour ago, Cam said:

I had thought I had to charge them directly with 67,2V, one at a time. Is them being in series (later on?) an issue?

Martys video bypasses the distribution board limit by charging via the cable that normally goes to the motherboard.
The intention isn't to balance, so all packs are done at the same time.

Each of the four packs will still balance - just if one of the packs is to unbalanced it could stop charging (like the power distribution board seems to do, too)

In such a case one has to try to balance this unbalanced pack by some charge and _rest_ cycles before the whole battery can be fully charged again. Or one has to replace this pack.

It could be that all four of your packs are in good enough condition so that normal direct charging of all of them together (as it normally should happen) just works and balances some small differences if present. And just the power distribution board messed up charging...

1 hour ago, Cam said:

I would have thought doing a pair at a time would be better for balancing (or even better, individually),

No. If they are "in good enough" condition each pack will balance enough during the whole charge cycle. Just heavily unbalanced packs could need several cycles.

1 hour ago, Cam said:

however it might upset something in the distribution board?

Sorry - i have no idea of the design of the power distribution board. Just that it messes up things ...

1 hour ago, Cam said:

Should I just try Martys approach and bet on the CV phase (repeated) to do the balancing?

If you do "direct" charging and the battery reaches about the chargers no load voltage and keeps about this voltage (for some hours) they are finely balanced and need no special treatment.

If any pack is too unbalanced you could notice it by premature charge cut off by this packs bms.

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Keep in mind that your original question in this post applies to a >1 year old wheel. Begode/Extreme Bull wheels not employ smart BMS battery systems so you can monitor the health of every cell (something I rarely ever bother to look at). Just wanted to clarify this discussion so people don't think it applies to all Begode/Extreme Bull EUC's.

I really don't worry about this stuff much any more. I have various wheels from 6-years old up to new. They all charge just fine and operate as to be expected. In over 45-wheels that I've owned and many more that I've tested I have yet to have a battery pack failure. It happens but is fortunately rare.

I try to encourage people to enjoy the EUC experience and not to dwell on the charging process and try to baby the batteries so they last 10-years with optimal performance. Life is too short :D

Having said all that, I have had a couple situations where I need to charge the battery packs independently. For the technically minded this is very easy. Best done with a newer generation of fast charger (I use a Roger Charger). You have to make an adapter cable that allows you to plug the charger into an individual battery pack.

I've done this with the EX30 and Master Pro, both 134.4-volt wheels. So I set the fast charger to 67.2-volts and charged each battery pack separately. The BMS will manage the charging. The power distribution board is not in the loop.

I highly recommend the Roger Smart Charger to avoid the idiosyncrasies of the cheap stock chargers.

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Posted (edited)

Thank you for the details @Chriull,
I will try charging all the packs at the same time while via but bypassing the power distribution board. It does indeed seem like it will allow for classic BMS balancing. Will repeat a few times (just discharge enough to charge again) and see how it goes.

@Marty Backe Thanks for mentioning the possibility for charging the packs independently, if the grouped method won't have them balance I will try that. I'm glad we don't have more failures than we do, and I understand your approach, but when EUC (or even just a battery pack) is limited by budget, and on top there are 8 flats above ones own, battery health paranoia kicks in 😅

I should receive the connectors to make an adapter in a few weeks, will update when there are any news.

edit: I suspect this (my above experience) is the case for many people (seing the various accounts of behavior from that board) + those who don’t care to notice. I do hope (and would prefer) Marty to be right in his relaxed attitude :) 

Edited by Cam
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51 minutes ago, Cam said:

I will try charging all the packs at the same time while via but bypassing the power distribution board.

Not saying you shouldn't, but just so you're aware, it's suspected that by-passing the dist board also by-passes the charge stop safety which we believe is now on the dist board rather than on the BMS.

So if you reach peak voltage on a cell the pack will still keep accepting the input voltage and the bleed resistor may not be able to deal with it.

Theres a lot of if's and maybe's in there but just thought you should be aware.

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Posted (edited)
1 hour ago, Planemo said:

Not saying you shouldn't, but just so you're aware, it's suspected that by-passing the dist board also by-passes the charge stop safety which we believe is now on the dist board rather than on the BMS.

So if you reach peak voltage on a cell the pack will still keep accepting the input voltage and the bleed resistor may not be able to deal with it.

Theres a lot of if's and maybe's in there but just thought you should be aware.

Thank you for the tip. Yet a complication introduced by that board.. I wish manufacturers would just stick to the trusted and tried if they don't have anything better to bring.. We've seen this with KS as well..

Anyhow: The stock chargers show 133V on my lousy multimeter. This one measures rather low (averaging all other measures it has taken) but not much more than a volt wrong (at that level). So the stock charger shouldn't be above 134.4V, very little chance it is, and if so not by much. It is also lower than my other 32S charger. My packs have 0.1V difference and it seems it keeps balancing from being able to happen, so between two risks I will take this one.

edit: We'll see if it helps with charge speed as I have that issue as well. I also think the interrupted CV phase might just be the continuation (at a higher SOC) of the same charge interruption.

Edited by Cam
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8 hours ago, Planemo said:

Not saying you shouldn't, but just so you're aware, it's suspected that by-passing the dist board also by-passes the charge stop safety which we believe is now on the dist board rather than on the BMS.

So if you reach peak voltage on a cell the pack will still keep accepting the input voltage and the bleed resistor may not be able to deal with it.

Theres a lot of if's and maybe's in there but just thought you should be aware.

I don't think that's true. We have a lot of local riders who bypass the distribution board and fast charge all the time. The BMS is doing it's job. 

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Posted (edited)

To avoid connecting / disconnecting the motherboard many times (while doing balancing charges, not permanently): this setup should do right?

Basically just having the charger in parallel between the power board and the motherboard, as a temporary setup while repeating balancing charge / discharge.

Just to confirm in case..

Edit: Could have a XT60 between the GX20 plug and the rest of the setup to avoid a large metal connector in there (even though it could be taped for protection and there is plenty of space)

 

Boardbypass.jpg.0dfbced0a30f9559aecdc85a7298db87.jpg

Edited by Cam
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41 minutes ago, Cam said:

To avoid connecting / disconnecting the motherboard many times: this setup should do right?

As it seems some people are doing more or less exactly this without negative effects reported, but i did not hear of anyone analyzing in detail the power distribution board and the used bms.

So it's guessing and rumours... :(

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10 hours ago, Marty Backe said:

I don't think that's true. We have a lot of local riders who bypass the distribution board and fast charge all the time. The BMS is doing it's job. 

Marty I would never argue with you bud, but as you say, we simply don't know for sure about the charge stop function when bypassing.

If the charge stop IS bypassed, thats a very real risk that people need to be aware of. I would try it, and I know you have, as have many others for some considerable time, but I think we need to raise the point when people may not be aware, especially those with less power system savvy than you or I.

And yes, the BMS will still certainly work without bypass and try to keep the cells balanced as best it can but the charge stop is a separate and very valid safety function because if one or more cells are too much out of balance (how much is too much? Again we don't know) one or more could well go over critical peak voltage yet the charger will still keep pumping current in there and theres every chance that the bleed resistor on the critical cell/s wont be able to bleed it off fast enough. This issue is, after all, the primary reason for charge stop being there in the first place, second being to safeguard from a charger voltage set too high.

 

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2 hours ago, Planemo said:

If the charge stop IS bypassed, thats a very real risk that people need to be aware of.

Did someone take a look at the BMS? If they still have as all other bms the single cell overvoltage cut off implemented?

Or if the power distribution board cut off is just an additional overall voltage triggered cut off - which is set too low, so the whole cv stage is skipped?

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Posted (edited)
2 hours ago, Chriull said:

Or if the power distribution board cut off is just an additional overall voltage triggered cut off - which is set too low, so the whole cv stage is skipped?

I would have thought this, but sadly (as you said) we can only guess because AFAIK there are no pictures of the Commander pro BMS.

The xxx power distribution board is the same as on other Begode EUCs though, so I suppose an other 32S Begode BMS (that isn’t « smart ») would give us the some info. I will try to find some good quality pictures of those using the week-end. If nobody have opened their battery packs; which I doubt, there should be pictures of the spare part at sellers.

Edit: here are some photos of Master BMSs, not so clear; will find better.

Edited by Cam
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38 minutes ago, Chriull said:

Did someone take a look at the BMS?

No they haven't, which is the problem. It was requested that Roger try to establish this given he was the founder of the bypass mod but to my knowledge neither he nor anyone else has confirmed re the charge stop question.

38 minutes ago, Chriull said:

Or if the power distribution board cut off is just an additional overall voltage triggered cut off - which is set too low, so the whole cv stage is skipped?

It could be a secondary cutoff, but again, we're guessing. What are the chances of Begode building two independent charge cut-offs on their wheels?

What we do know is that these later wheels have a comms wire to the board which the older wheels didn't have. We also know that there are mosfets fitted to the distribution board which appear to be very similar to the charge cut fets that were mounted to Begode BMS's of old. Alternatively, these could be charge-on fets for the input. We simply don't know until someone, somewhere, pulls apart a fairly recent Begode BMS to see whether it looks like theres any charge cut fets on it. If thats not conclusive the only option would be to take a say 80% charged pack, charge a single string up to 4.2v, apply a normal charge to the pack input and see if the 4.2v string climbs beyond 4.25v or so (being ready to hit the charger power off switch if it does!)

As you can imagine, theres not an abundance of people out there who want to strip down a perfectly good pack and it's not really been long enough for duff ones to rear their heads. So we are where we are.

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3 hours ago, Planemo said:

Marty I would never argue with you bud, but as you say, we simply don't know for sure about the charge stop function when bypassing.

If the charge stop IS bypassed, thats a very real risk that people need to be aware of. I would try it, and I know you have, as have many others for some considerable time, but I think we need to raise the point when people may not be aware, especially those with less power system savvy than you or I.

And yes, the BMS will still certainly work without bypass and try to keep the cells balanced as best it can but the charge stop is a separate and very valid safety function because if one or more cells are too much out of balance (how much is too much? Again we don't know) one or more could well go over critical peak voltage yet the charger will still keep pumping current in there and theres every chance that the bleed resistor on the critical cell/s wont be able to bleed it off fast enough. This issue is, after all, the primary reason for charge stop being there in the first place, second being to safeguard from a charger voltage set too high.

 

Agreed. If one of the cells becomes unbalanced and reaches 4.2V much earlier than the others, continuing to charge with high current will lead to a situation where power needs to be diverted around this cell and dissipated as heat within the BMS. This scenario is highly undesirable and could potentially result in a BMS fire. 

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Posted (edited)

Cell group over voltage cut is part of CV phase balancing AFAIK, the cut of the distribution board cant do that function. I doubt (even Begode) would drop the former because of a second function that is not the same.. 

I’ll be looking for photos of BMSs used with that distribution board if anything can be seen from that.

Edited by Cam
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30 minutes ago, Cam said:

Cell group over voltage cut is part of CV phase balancing AFAIK, the cut of the distribution board cant do that function.

OK so what function are you saying the pack comms wire/cut on the distribution board is for? Simply an over-voltage on the input?

30 minutes ago, Cam said:

I’ll be looking for photos of BMSs used with that distribution board if anything can be seen from that.

I think you will struggle but it would be great if you do. We have visited this topic before on this forum btw, I will try and find the thread.

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6 minutes ago, Planemo said:

I think you will struggle but it would be great if you do. We have visited this topic before on this forum btw, I will try and find the thread.

 

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