Could my wheel catch fire soon?

[Stephens]

Hi, recently after connecting the unicycle to the EUC World application, I was getting a message about low voltage.

Since then, I've ridden several hundred kilometers on my unicycle, until it started to annoy me. I turned on the voice prompts and found out that it has to do with low voltage.

I would like to mention that the wheel has already traveled nearly 10,000 km, never ridden in the rain, very well maintained.

Some time ago I decided that they need to be dismantled, because I have seen and heard many stories about Gotway wheels. I noticed a flashing light on the ATE motherboard.

As I found out: ATE on the motherboard can be responsible for testing various components of the unicycle, such as the battery, electric motor, sensors, control system, etc. ATE can help detect problems in these components and facilitate the diagnosis and repair of faults.

Now the question for you, have you had such a situation before and do you know how to deal with it? I don't have the best memories with services and would rather avoid them.

[mrelwood]

The major concern here is of course the battery. Does it still charge to full? Has the range been decreased? Is there anything else that has changed in the wheel’s behavior?

[meepmeepmayer]

The voltage depends on the battery charge state. A full battery (charge to 100% and keep the charger in for longer) should be about 100.8V on an MSP. If you get that, the battery is good. If you get significantly less (especially more than ~4V less) there might be a problem (or it's just your charger). Check that, what is your max voltage when charging?

Not sure what EUC World's "low voltage" warning means. A battery loses voltage as it discharges and gains voltage when you recharge again. And since you can recharge and ride, it's not obvious what a permanent "low voltage" warning would mean. A battery that is permanently at a low voltage would be empty and not work.

Maybe EUC World also expects a higher voltage? Can you change what wheel model it thinks it connects to? Maybe it's just an app error.

You can also open a side panel and look on the sticker on the battery pack. If the cells used are LG M50T (not LG M50LT), then these are dangerous and have caused a few fires. Other cells didn't.

Fundamentally, "low voltage" would not lead to a fire. That happens when you overcharge (too high voltage) the battery, or the cells are bad ones (like the M50T). So I would not yet worry about a fire, but it's good to be careful and figure out what (and if) something is wrong with your wheel.

-

TLDR: check if your battery charges to 100.8V (or somewhere in that area), and check if you have dangerous cells (LG M50T). That's where to start.

[Stephens]

Thanks for your response.

Of course, I forgot to add that I had charged the battery several times at that time, and each time it showed 100.8V. I haven't noticed any drops in power (usually calm driving up to 30 km / h, sometimes 40) or range drops.

I've been using the EUC World application since the beginning of using the wheel and I don't know when this message started appearing.

I will check the battery model yet, although they seem to be fine.

[meepmeepmayer]

If the battery charges to full voltage, that pretty much means it must be good as new. I wouldn't know how it could be otherwise. So certainly no battery problem here (unless you happen to have the bad cells).

[alcatraz]

End charging voltage / range / charging time / charging behavior. 

This is where a bad pack shows its symptoms compared to a good pack. At first the difference is small, but it grows over time and use.

Edited April 20, 2023 by alcatraz

[Unventor]

Hi @Stephens this here is not what most like to hear....

Yes you EUC could catch fire. Any EUC can at any given point. The question is when and at what risk. 

 

That is a much hard question to answer. I looked at your profile and saw you are linked to Poland. Here you are in luck. I have had very good experience with

https://eunicycles.eu/

This reseller knows his stuff and can do different kind of services. Onething is what people advice over internet with limited info another is a hands on diagnostic. I personally don't this hat d's on beats internet advice, but that might just be me. 

I knoe it is a bit probative way of answer this. But this is my hearth felt adwise... Some takes chances other take risks... I like to minimize riskes but with EUC they will always be there. But what I can do to increase my chances to ride safely has to do with how I address the risk and how I prepare for risks. I ride in gear and spend fair bit of money on it. I stille crashed but with limited negative impact. But I just repaired my V11 and my other V11 is due for a drive board swap. I rather swap a part to keep risk low than take a chance. 

I do hope this helps you to find your balance this topic. There are people out there that can assist making right decisions but nothing is 100% no matter what you do? 

 

[0000]

On 4/20/2023 at 4:52 PM, meepmeepmayer said:

If the cells used are LG M50T (not LG M50LT), then these are dangerous and have caused a few fires. Other cells didn't.

Given the amount of fires that's still an ongoing thing, would it be prudent to have some kind of safety warning stickied somewhere on the forum for all models + years that included these LG M50T cells? Especially considering there was never a formal recall beyond the very laudable US-based eWheels one if I understand the situation correctly. Or maybe there already is and I'm oblivious...

To @Stephens, I wouldn't be personally comfortable storing a wheel with these cells without taking extreme precautions for mitigating fire risk, so if you don't know whether you have the 50Ts or not in your wheel, I'll just add to what the others already said. Definitely worth making it a priority to check. The thread linked above has around 10 recorded MSP fires, so there's that.

Edited April 21, 2023 by Vanturion

[mrelwood]

While this may sound like nitpicking, I think it’s important to differentiate dangerous cells from dangerous battery packs. Early V11 units and a few other EUCs have come with the dreaded M50T cells without spiking the fire charts in a meaningful way.

 The issue is specifically with Gotway/Begode 900Wh battery packs. The same cells on other battery packs doesn’t seem to burn significantly more often than any other wheel/pack.

[0000]

Thanks, couldn't remember if it was a matter of a flaw in the generation of LG 50T cells themselves or cells used in a configuration insufficient for the amount of power demanded by the motor controller. Or maybe you can't even say that, was it just how these particular 900Wh packs were built, a quality issue? I think I assumed it was an under-spec issue before.

[chanman]

I don't think we have a definitive cause, just what people have tried to reason out, but the blame was put on the power draw and also possibly the regen current going back in from the controller being above what the cells were rated to handle, since that was more of an issue on the lower capacity gotway models, the models with more parallels packs had less problems, and other brands using those cells without problems were more conservative with the power limits. The pack construction was very basic but that wasn't itself a hazard if the controller demands were within spec or more capable cells would have been used.

Edited April 21, 2023 by chanman

[mrelwood]

I remember discussions about the 900Wh packs’ nickel strips between series groups of cells to have been too thin, causing excess resistance and eventually burning out.

 Whatever the detailed reason was, it was those specific packs that peaked the fire charts to whole new levels.

[RagingGrandpa]

On 4/21/2023 at 6:43 PM, mrelwood said:

900Wh packs’ nickel strips between series groups of cells to have been too thin

Eh, not really. 
The 100V 900wh pack has a longer weld strip at cell 12, than in the other places. You could regard it as a "60A fuse". 
With two packs or more packs in parallel, this should not see more than 40A, and is not a problem. 

 

In an unrelated situation, Master V1 had all packs in series (no parallel packs), and so one weld strip carried the entire burden. Aggressive riders were able to melt the strip; but no pack fires have been reported from it. Then V2 and newer changed to parallel packs.