AirWheel X8 Stopped Self-Balancing/Engaging Motor?

[nickysneids]

Hi everyone!

As per my account you'll notice I'm quite new to this forum. Been riding for about two months and loving it but my EUC is currently shot so I'm very motivated to figure out how to fix it and learning a lot in the process. I haven't found much on this issue anywhere else and I originally posted about this on the EUC subreddit but I'll try my luck here!

Here is a link to the video that shows the issue: https://youtu.be/Mig6F0hZ-Jw

This happened after I started trying to 180 into reverse off a curb. It fixed itself after I recharged it but then I took it off another curb with no 180 attempt and it happened again. It hasn’t fixed itself after recharging. I’ve ridden it off of curbs before with no issue. My guess is the quick switch of motion combined with the small impact of dropping off the curb overloaded the self balancing motor, and it can’t re-calibrate.

Someone on reddit suggested I blew a fuse so I went in and tried seeing if there was a fuse blown... there wasn't. As far as I know there aren't fuses in these models. But there was a disconnected wire as you can see here:

I stripped down the end of the wire and soldered it back into the missing place, as well as clipping and gluing down the alarm wiring to get rid of the annoying alarm.

As you might has guessed, this did not solve the problem. In the video I have linked above, you can see that the EUC engages the motor but after a bit of strain stops and loses any self-balancing. After doing this work and recharging everything, it won't even do that. It turns on, power runs through, but no motor engagement at all.

I've since done research that suggest there may be a dead mosfet(s) but just barely understand what those do (pretty sure they are the metal bracket looking things at the top of this picture). Link to the thread that brought me to this conclusion here: https://forum.electricunicycle.org/topic/10556-airwheel-a3-broke-error-code-7/

Any and all help in this issue would be greatly appreciated! I don't have the budget right now to upgrade (although I've severely outgrown the limitations of this EUC hence the 180's) so I'd be so pysched to get this fixed and back into my daily commute!

Thanks in advance!

-Nick

 

[yuweng]

Since nobody reply, i'll give you my 2¢  Basic electronic board troubleshooting is not that hard but you'll need to use a multimeter. First you need to make sure that the battery pack is supplying 67.2 Volt into the controller board. 2nd is when it stop working/ buzzer beeping, if the voltage drop then its your battery pack problem, have you shunt the BMS. 3rd is measure all the hall wiring, motor phase to make sure that there is voltage, try unplug/ plug back, it could be just a contact problem, this video demonstrate it.

Component level troubleshooting is next but require skill & experience, the easiest is board level meaning confirmed its the board problem then replace the faulty board, problem solved  Try contacting Lz Lee or Jessi Wu for more info.

[Chriull]

@nickysneids - hello!

I'd also guess wildely, that this is your battery dying?!

Yours has some 16s1p configuration (16 cells and something around 130-180Wh)?

Shunting could help, but decreases your safety - once one has bad cells they have to be changed (or much better the whole back). Unfortionately 16s1p backs are just too weak to withstand the burden of EUC driving. Additionally these generation of wheels still had (too low) current cutoffs from the BMS while driving! Thats what presumably happened the first time you jumped off the curb. Charging or battery disconnect resets this kind off BMS cutoff. Against this "fault" the abovementioned shunting helps.

Second cause for BMS cutoff is a single cell undervoltage - in the battery packs some/one cell is the weakest. It get discharged and charged fully again first. And once it got stressed enough/aged/detoriated it will go under the voltage threshold of the BMS during a normal drive. Here the BMS ?normally? resets itself, because the cell regains its "normal" voltage quite quickly once not burdened anymore. And cuts off immediatelly again with the slightest burden... For such a case shunting can be dangerous (potential fire hazard). Here the only sound possibility is changing the battery pack/the aged cells.

As your wheel in the video looks operational but "just" no self balancing this is some error state the wheel encountered. This happenend too me seldomly with different wheels, if they can't initialize (whatever) and a simple restart helped. Also after a crash/incident/too much sideway leaning the wheel can behave like this.

So your probs could come, as written above from the aged battery, the hall sensors (here the cables could be broken were the leave the motor axle). Or the gyroscope on the mainboard - no valid "angles" reported to the cpu and so no self balancing is started?

If there was a broken wire, it would be very interesting which wire this was! I.e. were it leads to. 

Once one is broken, all other connections should be checked ery thoroughly.

Just one good news - its extremely unlikely a mosfet fault. Normaly with a broken mosfet the motor has a resistance if one tries to push the wheel while turned off. If one disconnects the board from the motor the motor spins freely again.

[nickysneids]

6 hours ago, yuweng said:

Since nobody reply, i'll give you my 2¢  Basic electronic board troubleshooting is not that hard but you'll need to use a multimeter. First you need to make sure that the battery pack is supplying 67.2 Volt into the controller board. 2nd is when it stop working/ buzzer beeping, if the voltage drop then its your battery pack problem, have you shunt the BMS. 3rd is measure all the hall wiring, motor phase to make sure that there is voltage, try unplug/ plug back, it could be just a contact problem, this video demonstrate it.

Component level troubleshooting is next but require skill & experience, the easiest is board level meaning confirmed its the board problem then replace the faulty board, problem solved  Try contacting Lz Lee or Jessi Wu for more info.

Hey @yuweng thanks so much for the response! I've actually decided to say fuck it and upgrade to the MCM5 as fixing a wheel so old and beat up seems like it will take too much time/effort to be worth the result. I really appreciate the resources and info you responded with though. Pretty interested in learning about this stuff so I'll digest this further and hopefully hold on to the information for future use!

2 hours ago, Chriull said:

@nickysneids - hello!

I'd also guess wildely, that this is your battery dying?!

Yours has some 16s1p configuration (16 cells and something around 130-180Wh)?

Shunting could help, but decreases your safety - once one has bad cells they have to be changed (or much better the whole back). Unfortionately 16s1p backs are just too weak to withstand the burden of EUC driving. Additionally these generation of wheels still had (too low) current cutoffs from the BMS while driving! Thats what presumably happened the first time you jumped off the curb. Charging or battery disconnect resets this kind off BMS cutoff. Against this "fault" the abovementioned shunting helps.

Second cause for BMS cutoff is a single cell undervoltage - in the battery packs some/one cell is the weakest. It get discharged and charged fully again first. And once it got stressed enough/aged/detoriated it will go under the voltage threshold of the BMS during a normal drive. Here the BMS ?normally? resets itself, because the cell regains its "normal" voltage quite quickly once not burdened anymore. And cuts off immediatelly again with the slightest burden... For such a case shunting can be dangerous (potential fire hazard). Here the only sound possibility is changing the battery pack/the aged cells.

As your wheel in the video looks operational but "just" no self balancing this is some error state the wheel encountered. This happenend too me seldomly with different wheels, if they can't initialize (whatever) and a simple restart helped. Also after a crash/incident/too much sideway leaning the wheel can behave like this.

So your probs could come, as written above from the aged battery, the hall sensors (here the cables could be broken were the leave the motor axle). Or the gyroscope on the mainboard - no valid "angles" reported to the cpu and so no self balancing is started?

If there was a broken wire, it would be very interesting which wire this was! I.e. were it leads to. 

Once one is broken, all other connections should be checked ery thoroughly.

Just one good news - its extremely unlikely a mosfet fault. Normaly with a broken mosfet the motor has a resistance if one tries to push the wheel while turned off. If one disconnects the board from the motor the motor spins freely again.

@Chriull Hey! Thanks for the response. Like I said I've decided to "let go" of this wheel although I might still try to fix it, and the information you've provided is useful for my overall knowledge of how EUCs work. It's possible I missed it, but what does BMS stand for? If I had to guess I'd say it was Backward Motor Stabilization but I really have no idea.

[Chriull]

7 minutes ago, nickysneids said:

but what does BMS stand for

Battery Managment System

Its the pcb were normally the liion cells are packed upon and all together put in the plastic wrap - at least with most EUCs.

[RokasK]

I know that it's an old post, but I just wanted to add my observation for anyone googling years later - what nickysneids missed is that in the vid the wheel actually balances for a few seconds proper before letting go. I would maybe not lean towards battery issues since the 4 led indicators on top continue showing full voltage. If it was a bad cell, it would cause a voltage drop which would be shown on the LEDs as at least one light gone (if I understand electricity). 

I would maybe start with the gyroscope malfunctioning since it looks similar how the wheels keels over if you tilt it to 45 degrees. But don't take me too seriously, just sharing my observations.