KS16S intermittent stutter while riding

[Smoother]

I have touched upon this briefly in another thread, but thought it deserved it's own thread on the off chance it saves someone from a nasty fall.

This report is not specifically King Song related as it could happen to any wire on any brand, any model. So read between the lines.

THE PROBLEM:

Recently, and also a few months back, I have noticed that after a jolt to the wheel, like when riding over a bump or jumping down a curb, the motor stutters.  By that I mean there is an obvious jolt after the obstacle has passed, it's quite disconcerting, but then it's over and riding continues as normal.

The other day, after this happened, I continued riding (at a much slower rate) and a few meters later it simply died, falling forward.  Because I was riding slowly, jogging off was a non event.  the outage is accompanied by a regular beep and four red lights on either side of the wheel.  I reset the wheel (off and on again) and rode on cautiously.  Approaching my car I rode up a 1 or 2 cm driveway bump, and it stuttered again, like I had run over a pebble, but there was no pebble because I scan my chosen route.  At this time I decided to get off and trolley it to the car.  I did actually ride it around a bit once at the car, but, being as there were no bumps, there were no further issues.

THE DIAGNOSIS:

The next day I tore my wheel down looking for a smoking gun.  I found none, initially.  So I put it ALL back together again, and turned it on. BEEP BEEP BEEP. It was in constant fail mode and no amount of resetting via the on/off switch would fix it.  At this point the air was blue.  But I tore into it again but only deep enough to expose the control board as I had a good suspicion it was here.  Because balancing was the issue and I had already checked the mosFETs for burn out (none found), I found the five hall effect wires where they enter the control board.  Moving them back and forth, I was able to make and un-make the problem.  I had found it.  There is a small break in the hall effect wiring as it enters the control board.  Unfortunately these connections are hard wired, so, difficult for a non electronics person to deal with.  The board is currently winging its way across Europe to EUC Poland's Richard to have a look at.

So for every EUC rider, regardless of brand, model, age:  if your wheel starts doing something unusual, especially if its undesirable, GET OFF IT.  or Ride it slowly, fully expecting a cut off at any moment.  At this point I might mention, don't keep riding it if a cut off would cause imminent danger to you, bystanders, or the wheel (e.g. riding beside a river, etc)

I have a video of the problem.  I'll see if I can upload it. 

Actually I shudder to think of the places I have ridden since the first stutter (which I initially attributed to a lower than normal battery - 36percent). i'm talking about cliff tops with sheer drops of hundreds of meters.  In fact I was heading up there on that exact ride where the first stutter happened.   And the second one happened the next day in the same area..

Edited December 13, 2018 by Smoother

[meepmeepmayer]

59 minutes ago, Smoother said:

So for every EUC rider, regardless of brand, model, age:  if your wheel starts doing something unusual, especially if its undesirable, GET OFF IT.

Yep. ANY new unexplained behavior = get off instantly and never use the wheel until you know exactly what the problem was and that it has been fixed.

[Marty Backe]

Totally agree. Our wheels are such simple devices (a battery, motor, and control board) that if a peculiar behavior develops, take that as a sign that something ominous is forthcoming.

Unlike our mult-wheel brethren, we can't just wait for the ultimate failure to occur before addressing it, because that can mean a faceplant.

My most recent example of this was my MSuper V3s+ that started vibrating a little as I initiated my riding. I stopped using it until I could open the wheel and discover loose control board mounting screws. Fortunately it was an easy fix for me.

[Smoother]

 

[Lutalo]

29 minutes ago, Smoother said:

 

Sounds very familiar. I have a KS18AY with the hall motor problem. Back when it began I engaged @Jason McNeil, @US69, @tinawong, and @Flora Yuan. They were all incredibly helpful in helping me to get to the bottom of the issue.

Flora and Tina gave me a great price on replacements and offered to upgrade it to an 18S for a very nominal fee. 

I fully intend to follow through on upgrading both if the AYs that I have, but since those conversations with Kingsong, I have purchased both an 18L and 18XL. So the problem has been that I have been too busy purchasing new wheels (Expensive. OUCH!) to prioritize fixing and upgrading the old ones.

Two of my sons are University students; UMD and UVA. My UMD student commutes to campus with the KS18L daily. My UVA student is jealous of this because he is stuck using an KS18AY from the olden days to tool around campus. My youngest son, a highschooler, can ride EUCs, but hasn't really seemed to embrace it yet as a hobby like his older brothers and me. 

I am considering purchasing one more 18L for my UVA student to ease his pain. Yes. I know. My kids are spoiled brats.

Maybe, I can turn my attention back to my old AYs this spring. Perhaps, I will upgrade them to 18Ss, and sell them. I attached a couple of photos of my AY with the failed hall motor. It basically needs a new board and motor. 

[Smoother]

My control board came back from  @EUniCycles.eu this week (he actually mailed it Dec 21, but it's taken all that time to get here).  Anyway, he removed the factory connector, which looks like a plug but you can't unplug (see video above).  He then soldered each of the 5 wires directly to the board, tossing the connector in the trash, I guess.  I repeated the test from the video and no faults were detected.  Before I buttoned it up I stuck the Hall sensor wires to the top of the capacitor with some electrical tape to stop them bouncing and vibrating as the wheel goes over uneven ground.  Took it for a 3 mile ride around the farm on rough dirt tracks, and everything worked fine.

If you open up your wheel for any reason, take the time to examine your Hall effect wires where they enter the control board.  If you can wiggle them around, then so can a rough road.  See if you can immobilize them as I did.  It might prevent a face plant, as even a momentary disconnect could fault the motor to "off" as it did in my case.

[Lateralus]

Hey @Smoother, thank you for sharing your experience! It might turn out I have a very similar problem, so I'm wondering how effective your repair was. Have you had any issues since the soldering and taping?