[WARNING] Gotway Nikola 100v 1800WH Battery Fire

[alcatraz]

Let me just add that as an amateur DIY I wouldn't hesitate to use these cells. They seem really good. But a pack is only as good as its management system and so maybe these cells require more balancing current to stay balanced, which I think most bms lack anyway. It's only adequate for brand new matched cells. As soon as they age a bit (any cell, not just these) the balancing current is inadequate. That's why I blame bms instead of cells.

It would be interesting to know if anyone with a first gen Nikola actually has the three lines on the negative pole.

Edited June 4, 2020 by alcatraz

[alcatraz]

If gotway still use the same bms boards today with 2000+Wh as they did 4-5y ago when capacities were 1300Wh then balancing currents are quickly diminishing in proportion to capacity. (Larger capacity packs take longer to balance). With the risk of sounding like a broken record, check your cell voltages everyone....

Edited June 5, 2020 by alcatraz

[houseofjob]

22 minutes ago, null said:

The Veteran Sherman has Panasonic NCR18650GA, is there any much chance these are of shady origin? Or are the issues mostly linked to rejected car batteries?

GA's and MJ1's are the tried-and-true cells for all manner of PEV, I'd be surprised if EUC manufacturers get fake ones, considering their supply chains for these cells used in many models over the years, have been well established. Not to mention, the Veteran guys are reportedly piggy-backing on Gotway suppliers.

[WI_Hedgehog]

2 hours ago, alcatraz said:

The tesla cells are just like the ones on ebay. On the bare metal outer body there's a square barcode on the side and three lines on the negative side. The positive side looks like a bowl basically.

Here's the current tesla motor cell market situation in China. The prices are dropping. Don't be fooled by the shrinkwrap or positive pole, it's the same cell underneath. Tons and tons and tons of cells. They come delivered to the multiple refurbishing factories in complete trailer truck loads. They are sold in bulk measured in tons, not quantities.

Anyway, I just suspect that these are the only kind of 21700 panasonic cells in circulation.

Well, there's the other shoe. I'm going to guess the reputable sellers got the Panasonic 21700 information from Gotway. Gotway possibly bought refurbished cells, and is now recalling them because, quite frankly, using used cells not designed for this task is generally a bad idea.

China does a lot of "recycling," that's how all those plastic straws ended up in the ocean. Now we have the evidence they imported TESLA batteries in bulk and are ripping them apart for the cells. I can understand third party sellers using them, figuring "they seem good and are cheap, they'll last six months." 

And as @houseofjob said, anything for a buck. If Gotway marketed the wheels as having TESLA cells, and they are actual TESLA cells, they're used cells, selling at more than 18650 prices. If that really is the case, I'd cancel my Veteran order knowing that will most likely be more of the same in a different wrapper. 

I read the top EUC racers build their own battery packs because factory "isn't great." Maybe this will be proof. Gotway quality was not good in other areas, I can understand it could be horrible here too.

Lot of speculation, but enough proof for me to wait to see how InMotion's suspension fairs.

Thanks guys, this really shed light on the rumors. 

[davinche]

Is Gotway recalling them? AFAIK only Ewheels (and now Ecodrift) are recalling the pana 21700 battery packs.

Edited June 5, 2020 by davinche

[WI_Hedgehog]

46 minutes ago, davinche said:

Is Gotway recalling them? AFAIK only Ewheels (and now Ecodrift) are recalling the pana 21700 battery packs.

I think it's possibly more like top-tier sellers forcing battery exchanges, and I should have stated that more clearly. Gotway is probably not going to do more than they absolutely have to. If that is the case, it's potentially very short-sighted, and could cause a similar ban to the cheap-China-hoverboard ban where poor lithium battery management caused a fire in a plane's cargo hold leading to a complete ban on low-quality imports for a while.

(I know someone who lost $150,000 because the ship was prohibited from unloading the hoverboard cargo. Of course, the Chinese were already paid, so what did they care? They didn't. And that ended a lot of sales in the short term, and led airlines to ban lithium batteries. Again, the Chinese didn't care. So in this case, it's possible we'll see more Gotway/used TESLA cell fires in the future. IF that's the case, I hope it's only a Gotway ban vs. a wheel ban.)

[Ben Kim]

5 hours ago, null said:

The Veteran Sherman has Panasonic NCR18650GA, is there any much chance these are of shady origin? Or are the issues mostly linked to rejected car batteries?

Assuming they are legitimate Sanyo GA cells, I would imagine a very low failure rate.  I wouldn't be surprised if their packs are built by the same factory that builds Gotway's batteries, and say what you want about Gotway's overall QC, their history of battery safety has been relatively good.  It's very difficult to use fake GA cells because a 3400+mAh 18650 is hard to fake (and easy to detect via range test).

Edited June 5, 2020 by Ben Kim

[alcatraz]

There are two kinds of Panasonic GA cells. Chinese made and "overseas", probably south korean/japanese.

[Ben Kim]

Just now, alcatraz said:

There are two kinds of Panasonic GA cells. Chinese made and "overseas", probably south korean/japanese.

There is the Sanyo variant (made in Japan) and the Panasonic variant (made in China), both perform more or less identically, however from what I've seen, the batteries inside Gotway wheels use the Sanyo variant (no Panasonic logo imprinted on the wrapper).

[null]

Thanks a lot for the info everyone, sorry didn’t want to derail here but while Panasonic and safety was at the table 😄 Glad for the Veteran.

[meepmeepmayer]

10 hours ago, null said:

The Veteran Sherman has Panasonic NCR18650GA, is there any much chance these are of shady origin?

Those are 18650s and are proven good. They are the 3450mAh cells Gotway used til they switched to 21700s (and soon after to LG M50T 21700s). There was never any problem with these cells. They are beyond any doubt good.

The questionable (literally, doesn't mean there must be anything wrong with them, there's just some uncertainty right now) cells are Panasonic 27100s that (rumor only!) may have been taken from used Tesla battery packs.

Two completely different things. No reason to be concerned at all about the Sherman battery.

Edited June 5, 2020 by meepmeepmayer

[houseofjob]

10 hours ago, davinche said:

Is Gotway recalling them? AFAIK only Ewheels (and now Ecodrift) are recalling the pana 21700 battery packs.

Outside looking in, I'm seeing a typical Gotway response: don't proactively address the wheels already sold and out-in-the-wild (aka recall), but just switch new wheel mid-production to the LG M50T 21700's they seem to be using now, based on current 21700 Nikola product pages.

 

7 hours ago, alcatraz said:

There are two kinds of Panasonic GA cells. Chinese made and "overseas", probably south korean/japanese.

Blasphemy! Koreans have too much pride to manufacture Japanese batteries, when they have their own market leaders in Samsung & LG, the latter whose MJ1's are in direct competition with GA's! (I'm Korean if you can't tell)

Edited June 5, 2020 by houseofjob

[WI_Hedgehog]

HOW EUC FIRES ARE GOING TO BECOME MORE COMMON

SUMMARY: To minimize the risk, use the Charging Best Practices.

 

A new BMS thread popped up that relates to what we've been talking about with balance charging. The BMS got cooked.

This post builds on how cells get out of balance, and state what happens next.

This problem is compounded by using any/all of: recycled cells, charging to 80%, and fast-charging.

To quickly recap, one of the dangers in using recycled cells is some cells will be near their End Of Life and start to go out of balance quickly, which is unexpected on a wheel less than two years old. Battery voltage reported in an app and on the wheel is an average across all cells and will read as somewhere between 25% and 50% battery remaining, but the weak cell/cell group voltage will be below 3.00V, and the BMS in EUCs is not monitoring for this condition. As the rider continues on, the strong cell/cell group voltages will continue dropping (say 3.5V), but the weak cell voltage will go below Critical Low Voltage (say 2.5V). This causes a permanent chemical change in the weak cell/cell group where the cell shorts, as if removing it from the circuit.

The full charger voltage is applied to the remaining cells, as stated previously. Here's what happens next:

Weak/used/older/recycled/aging and "cells in the middle of the pack that can't cool as fast as the outer cells" have less capacity than strong cells, therefore, they reach full capacity (4.20V) sooner. The charger applies power across the whole pack, so the weaker cells which are fully charged must somehow stop themselves from being charged; because they don't have this ability, the Battery Management System does this by employing a balance circuit for that cell/cell group. The balance circuit turns on and bleeds off current from the charger for that cell group. Normally this works well.

Consider the following:

• Fast charging increases the current through the battery pack, and therefore through the cells. The balance circuit resistor must bleed off this extra current.
• When there are dead cells, the full charger voltage is applied to the remaining cells. This higher voltage is applied to the balance circuit resistor, which must now bleed off the extra current caused by the extra voltage.

In both cases, the resistor must dissipate more power than it was designed to handle, and it's a very tiny resistor as seen in BMS pictures. The resister overloads, and the balance circuit can't dissipate the extra power. In the worst case scenario the resister burns out.

Either way, the balance circuit can't dissipate the extra power and the cell group continues charging to the point of being over-charged, damaging the cell group. (This can quickly cause those spiky dendrites to form.)

Hopefully the BMS stops the charge, preventing a fire. However, this leaves cells in an unbalanced state, worsening the battery condition (a circular problem).

Because there is no alert, the user sees a shorter charge and shorter riding time. There is also more stress on what's left of the battery, especially on the under-charged cells. With the added stress, when cells go under-voltage they heat up quickly, potentially starting a fire. (There is a safety mechanism, hopefully it works. If not...)

To minimize the risk, use the Charging Best Practices.

Once the rider sees shortened charge and riding times, cells should be capacity tested and matched. Given the time & cost in the teardown, testing, and rebuild process, coupled with the expected lifespan of the used cells in an EUC application, it's quite possibly best to start with new cells and rebuild a pack with a new, unstressed, reliable BMS, depending on the condition and number of the surviving cells, plus taking new, longer-lasting cell technology into consideration.

Edited June 5, 2020 by WI_Hedgehog

[Chriull]

15 minutes ago, WI_Hedgehog said:

Consider the following:

• Fast charging increases the current through the battery pack, and therefore through the cells. The balance circuit resistor must bleed off this extra current.
• When there are dead cells, the full charger voltage is applied to the remaining cells. This higher voltage is applied to the balance circuit resistor, which must now bleed off the extra current caused by the extra voltage.

In both cases, the resistor must dissipate more power than it was designed to handle, and it's a very tiny resistor as seen in BMS pictures. The resister overloads, and the balance circuit can't dissipate the extra power. In the worst case scenario the resister burns out.

Sorry, but that's wrong. There is always the same voltage (between 4.2 and 4.2xV) on the resistor - so they bleed off an equal current no matter which charging current flows.

Fast chargers probs could just arise waris  i see by now (possible) overburdening some input protection circuitry, connectors, wires, or if it were "real fast" charging overheating the batteries.

Edited June 5, 2020 by Chriull

[WI_Hedgehog]

1 hour ago, Chriull said:

Sorry, but that's wrong. There is always the same voltage (between 4.2 and 4.2xV) on the resistor - so they bleed off an equal current no matter which charging current flows.

Fast chargers probs could just arise waris  i see by now (possible) overburdening some input protection circuitry, connectors, wires, or if it were "real fast" charging overheating the batteries.

The resistor will try to dissipate charge current when cell voltage is above 4.20V.
(Note how many cells are in Parallel doesn't matter unless there is more than one BMS, as one resistor R is used per cell group, regardless of the number of cells in the group. This is the problem with basing charger current on what the cells in parallel can handle instead of what the BMS can handle.)

P = I x E

Power is greatest at the Constant Currant -> Constant Voltage crossover point. If we take the charger to be 84V 2A (note 3A was used be the thread starter, but I'm using a more conservative 2A, and not implying his charging habits are the cause of the fire):

E (84V) / 20 cells = 4.2V average, varies by cell imbalance

I (2A) / 20 = 0.1A

P(resistor) = I (0.1A) x E (4.2V) = 0.42W (at normal clamping voltage)

However, with two dead cells:

E (84V) / 18 cells = 4.67V average, varies by cell imbalance

I (2A) / 18 = 0.11A

Granted, the balance resistor is going to try to clamp the voltage at 4.2V, but as other cells reach full charge the E across all cells tries to approach 84V:

P(resistor) = I (0.11A) x E (4.35V) = 0.48W (attempting 4.20V clamping voltage)

Not the end of the world: 1 - 0.42W/0.48W = 12.5% overload. Except the Chinese are usually trying to cut costs and don't build in a 1.5x safety factor.

If we assume the higher Gotway Low Voltage Cutoff of 3.30V (average):

3.30V x 20 cells = 66V, 66V / 4.2V/cell = 15.7 (meaning 4.3 cells can die and the wheel will still run)

So the worst case scenario is 4 cells die and the wheel still works after being charged. We can therefore calculate the very real possibility 3 cell groups die:

E (84V) / 17 cells = 4.94V average, varies by cell imbalance

I (2A) / 18 = 0.117A

P(r) = I (0.117A) x E (4.7V) = 0.55W (attempting 4.20V clamping voltage)

1 - 0.42W/0.55W = 25% overload this can burn out the resistor, which then charges the cell to cutoff.

Granted, we hope the BMS charge shutdown circuit kicks in before 4.7V, and it almost always will kick in far below that.

We do have to remember all parts have an acceptable tolerance range, which in the US is typically 5%, so if we assume China uses 10%:

4.27V shutdown with 10% acceptable variance = 4.62V (pretty close to 4.7V, isn't it?)

However, on average that's 4.48V, so we might be a bit over-estimating. Then again, @houseofjob has taken me to task for thinking this actually happens in China. Even if we tighten the assumption to 5%, that means some wheels will have 4.48V cutoffs, if the cutoff circuit is reliable.

While the numbers can be argued, what we do know though, is we're starting to see circuit boards -and wheels- burning up. (and remember, a 2A charger was used in these calculations, not a 5A Fast Charger)

 

Edited June 5, 2020 by WI_Hedgehog

[Planemo]

31 minutes ago, WI_Hedgehog said:

(Note how many cells are in Parallel doesn't matter unless there is more than one BMS)

Most packs have their own BMS. So in my wheel I have 4. My 84v had 3 and a stock wheel generally 2.

31 minutes ago, WI_Hedgehog said:

While the numbers can be argued,

You are right, we can argue them all day long but it means the grand sum of jack squat without knowing the limits of the charge components (which, with all respect, you dont).

31 minutes ago, WI_Hedgehog said:

what we do know though, is we're starting to see circuit boards -and wheels- burning up.

No we're not. Theres been 2 recent ones to my knowledge, Vs the 1000's of wheels out there.

31 minutes ago, WI_Hedgehog said:

(and remember, a 2A charger was used in these calculations, not a 5A Fast Charger)

Its this insinuation that A: a 5A charger is 'fast' and B: the suggestion that they have anything to do with the recent fires that irks me.

How I wish we could get away from the 'fast' tag when talking about 5/6A chargers. They are not. You even suggest yourself that the amp rating of the charger in question is not an issue so why even bring up amp rating on this specific wheel fire thread?

I accept that an increase in amps can highlight an issue already present, but that doesnt make the charger the cause.

I have used a 5A charger on many occasions on a Z6 and Z10, and a 6A on an MSX 84v and 100v with zero issues. In fact, everyone in my riding group uses 6A chargers because if we didnt we would spend half the day charging. If something was going to go up in flames due to an overworked BMS, it would have happened by now. So lets stop talking about so called wafty BMS capability and 5A chargers like they are the spawn of Satan and instead focus on the root cause of the fires.

Dont get me wrong, I like your knowledge of physics and electrical engineering but the simple fact remains that there was another issue with the wheels that recently went up and I dont want readers to point fingers at either a 5A charge current or a BMS that couldnt handle it.

[RagingGrandpa]

22 hours ago, xorbe said:

The stand-alone balancers that I have used balanced cells whether the battery was full or not.  I don't think "100%" matters, it's not like the balancer knows this.

Stand-alone balancers work very differently from built-in Battery Management Systems. If the EUC BMS were to do resisitive balancing 'all the time,' it would bleed energy continuously and decrease the range of the EUC.

EUC BMS perform "top-balancing" - they engage a balance resistor for a cell only once the cell voltage exceeds 4.2V. This is why fully charging matters. More here.

1 hour ago, WI_Hedgehog said:

The resistor will try to dissipate charge current when cell voltage is above 4.20V.

...clamping voltage...

No. The balance resistor follows Ohm's law. It is connected in parallel with the cell, therefore the cell voltage dictates the voltage across the resistor, and therefore its current. There is no 'clamp' (perhaps you're thinking of a diode?). Charging current will continue to flow, and the cell voltage can continue to rise. If the cell voltage (of any cell) exceeds 4.25V (Gotway), the BMS shuts off the charging input and stops charging the whole pack.

Edited June 5, 2020 by RagingGrandpa

[Chriull]

6 hours ago, WI_Hedgehog said:

P(resistor) = I (0.11A) x E (4.35V) = 0.48W (attempting 4.20V clamping voltage)

The voltage (with a functional BMS) over the bleeding resistor can never reach 4.35V. As @RagingGrandpa analized a GW BMS the BMS cuts off the charging input at 4.25V. In the post "battery degradation" from last year i got the hint of another member that KS BMS cut off charging input at single cell voltages at 4.24V. The "worst" specifications from noname aliexpress BMS i've seen is single cell overvoltage shutoff at 4.28V.

Also with your 

6 hours ago, WI_Hedgehog said:

I (2A) / 18 = 0.11A

you are implying that the whole current flows through the bleeding resistor. But as the resistance of the bleeding resistor is fixed and the voltage at the bleeding resistor can only be between 4.2 and 4.2xV the current flowing through the resistor is limited to I=[4.2xV..4.2V]/R. As @RagingGrandpa has already written - the resistors current follows the ohm's law and voltage range is very limited - so there is just a very limited current range which does not depend on charging current!

The "rest" of the current flows through the paralleled cell (group)

But from this an additional point to 

7 hours ago, Chriull said:

Fast chargers probs could just arise waris  i see by now (possible) overburdening some input protection circuitry, connectors, wires, or if it were "real fast" charging overheating the batteries.

If one charges battery packs with bad/dead cells they have to dissipate power proportional to the square of the charging current!

So "faster" charging increases risk of thermal runaway with bad packs. Bad packs have to be discarded/replaced/repaired - they are a potential fire hazard especially while riding or charging. Cells in the "last stage of dying" can afaik (imho) also cause fire without any external influence!

So this is in reality no adfitional/increased risk of using a fast charger but the failure of "misusing" a faulty pack. (Which is hard to be known by an average EUC rider... )

[travsformation]

So assuming I'm a bit challenged in the mental department (at this point in the conversation I'm starting to feel like I am...)...

• Is it safe to keep using my 5A charger on my 16X and 18XL?
• Every how many charges should I charge to 100%, if not always?
• Is it preferable to only use 5A charging when in a hurry, and set the charger to 3A for overnight charging, for instance? Speaking of which:
• Can I safely charge my wheels overnight without worrying about waking up to the smell of BBQ's EUCs? (never done it before, but a doubt worth addressing)

 

[Chriull]

1 hour ago, travsformation said:

So assuming I'm a bit challenged in the mental department (at this point in the conversation I'm starting to feel like I am...)...

• Is it safe to keep using my 5A charger on my 16X and 18XL?

Yes.

To decide which charger is better to use for saturation charge one could compare output voltages...

Quote

• Every how many charges should I charge to 100%, if not always?

Afair there were no reports of members telling they charged to 100% every x times and the batteries got misbalanced?

Imo they had chargers with too low output voltage or never charged fully.

Concluding from this that it is safe, or how often 100% charges are needed is quite vague? (Especially if based on what i remember )

Quote

• Is it preferable to only use 5A charging when in a hurry, and set the charger to 3A for overnight charging, for instance?

For the ks18xl (20s6p) 5A charging is about ~0.24C and 3A ~0.14C charging. So i won't see any real difference - it's both slow charging...

You ever tried to (estimate) charging time until green light comes on? Charging fully could take (approximately) about the same time 5A charger is faster while the CC phase, but there is more saturation charge needed while the CV phase.

Quote

• Speaking of which:
• Can I safely charge my wheels overnight without worrying about waking up to the smell of BBQ's EUCs? (never done it before, but a doubt worth addressing)

 

Tldr: no, but...

 

With working smoke detectors and working batteries risk should be quite low?

Quality LiIon cells should be quite stable and robust. Quality issues can be (quite) ruled out after first weeks/month of use and battery voltage/charging behaviour is "monitored" for odd bahaviour.

... and it makes a difference if the ne lives on the 7th floor of an appatment building or if obe can charge in his garage beside the house...

[travsformation]

4 hours ago, Chriull said:

Yes.

To decide which charger is better to use for saturation charge one could compare output voltages...

Yes it's safe or yes, I'm mentally challenged? 

JK, thanks!

4 hours ago, Chriull said:

Afair there were no reports of members telling they charged to 100% every x times and the batteries got misbalanced?

Imo they had chargers with too low output voltage or never charged fully.

Concluding from this that it is safe, or how often 100% charges are needed is quite vague? (Especially if based on what i remember )

I've always charged my wheels to 100% after receiving them, before the first use. After that, I usually charged to 100% until I got the fast charger, and charged to 90% to extend battery lifespan, charging to 100% maybe every 3rd or 4th charge. But from what I've read, the benefits pf charging to 90% are negligible at best and not charging to 100% comes with risks (packs not being balanced) that I get the impression, outweigh the benefits.

4 hours ago, Chriull said:

For the ks18xl (20s6p) 5A charging is about ~0.24C and 3A ~0.14C charging. So i won't see any real difference - it's both slow charging...

You ever tried to (estimate) charging time until green light comes on? Charging fully could take (approximately) about the same time 5A charger is faster while the CC phase, but there is more saturation charge needed while the CV phase.

Thanks!

What difference is there (if any) in terms of safety / battery longevity between charging with a selectable-current fast charger set to 3A, vs. using two OEM 1.5A chargers? The OEM charger don't switch to CV do they?

4 hours ago, Chriull said:

Tldr: no, but...

 

With working smoke detectors and working batteries risk should be quite low?

Quality LiIon cells should be quite stable and robust. Quality issues can be (quite) ruled out after first weeks/month of use and battery voltage/charging behaviour is "monitored" for odd bahaviour.

... and it makes a difference if the ne lives on the 7th floor of an appatment building or if obe can charge in his garage beside the house...

Yeah. Minimal but...can't be discarded 100%. Enough for me not to do so. Especially considering I live in a 4th-floor apartment and will be spending this summer in motorhome with all cabinetry made of wood... 

Thanks for taking the time to answer, and for doing so in layman terms that even I can understand! 

Edited June 11, 2020 by travsformation

[travsformation]

On 6/5/2020 at 4:38 AM, WI_Hedgehog said:

And as @houseofjob said, anything for a buck. If Gotway marketed the wheels as having TESLA cells, and they are actual TESLA cells, they're used cells, selling at more than 18650 prices. If that really is the case, I'd cancel my Veteran order knowing that will most likely be more of the same in a different wrapper. 

How certain are we about this? What's the source of the Tesla pack pics shared in this thread and has the info been verified?

I've been pondering the idea of adding an MSP or a Nikola to my collection lately, but if the above is true, I'm very weary of getting a GW right now. Which of their wheels use Tesla cells?

[Lefteris]

Well charging over a smart plug is a smart idea to say, you need 3 hours and 45 minutes to go from 30% to 100%, then tell the plug to switch off the power in 3 hours and 30 minutes, what would 15 minutes of power loss is to a wheel.

That is what i do with my Nikola Plus 100V with 21700 LG cells, also measure Watts and time taken etc.

[alcatraz]

I have a 5y old pack that's gone 10.000km. Ridden in -20C up to 30C. Left at 100% charged sometimes for weeks at a time. Sometimes left connected to the charger for a couple of days. Sometimes charged right after depleting the battery, etc, then straight out riding.

The cells are all perfectly balanced. I haven't had the need to do any manual balancing.

A second pack I got (second wheel, same model) that did 3000km, had severe imbalances. I had to break it apart to save the cells that were being killed by the dead cells.

The two packs have the SAME cells and the SAME bms. One works, one doesn't.

From the outside you can't see any damage. The wheel doesn't give me any error codes or warnings, even when doing the "self diagnostic" in the app. A nice little green checkmark appears next to the battery, after it slowly reaches 100% checked. All you see are a few km less range on the damaged pack, and a rather short delay between 5/5 bars switches over to 4/5. But with wheels so old it's hard to tell which pack has done what mileage (lets say you buy 2nd hand). And who has two wheels of the same kind to notice a behavior difference like that?

So there's the crux. Because rider A has no problem doesn't mean rider B with the exact same gear is safe.

A wheel with 10kkm can be in better shape than a wheel with 2kkm on it. The scary side is that a 2kkm wheel could be a fire hazard without any indication of it. Sorry to be so blunt about this. Just sharing my experince. I see several posts from people that appear astonished of how it can happen.

Edited June 12, 2020 by alcatraz

[davinche]

So... does leaving it on the charger fix the issue? How did you tell one pack had severe imbalances?