Gotway Oscillation Issue - Revisited in 2018?

[csmyers]

I wish I didn't have to make this post.

I have about 315 miles on my new ACM2 and it's been great, no prior problems. I really appreciate the increase in power and range over my 67v ACM v1. I bought it in new condition from an eBay seller and they were friendly through the whole purchase process. Due to the condition and the lowered price I had a feeling it had been sitting around for a while - more on that later.

Yesterday I was riding normally and there were two instances in which, on an sloped transition from the sidewalk to the street, the wheel started oscillating and cut out. The first time I thought I had simply over-leaned the wheel and kept riding. Later that night I was coming back home and the oscillating was more pronounced before an obvious cut-out. I was able to run out both instances so I never got a scratch, but the second time I was definitely traveling over 20mph. 

Motor code: 171100303HB          Board code: 180120011

What do you think? @Marty Backe suggested I might have a loose connection but looking at it now everything looks and feels just as solid as the day I got it. Is it possible I have a wheel with the oscillation issue? @Jason McNeil do the board and motor codes match up with the wheels you were re-flashing last year? I'd love to know everyone's thoughts. Thanks!

 

[meepmeepmayer]

Bad production dates were about 20th April 2017 to end of May 2017 (the production date can be found on the sticker on the box, as part of the serial number). That apparently was when boards with the bad firmware were used.

But that was a very specific issue that was fixed. Loooooooong ago. Since July 2017. So it can't be that. And there hasn't been a single oscillation problem with any Gotways after that. So I don't think this is a general problem.

On the other hand, oscillation is oscillation, and you described pretty unambiguously that your wheel was definitely oscillating.

No idea what's going on, but I'd get a new board. Probably that will fix it.

The only other oscillation issue I know of is with the V8 under unlucky and very high stress spikes, that was theorized to be due to the firmware not being able to deal with the voltage drop that can happen on the small (2P) battery. Since the ACM2 is 6P (and no Gotway firmware ever showed that problem), that can hardly be it. Maybe check the battery cables if you can find anything. Did you ever do a range test or confirm the battery is fully available? But as you say you enjoy the increased range...

So check the cabling, and if nothing obvious turns out, I see no choice but to get a new board. Maybe yours is just bad? Especially as this problem appeared on a previously working wheel, something must have broken.

Edited October 15, 2018 by meepmeepmayer

[Marty Backe]

Although the symptoms may be similar, I can't believe it's a firmware bug. Regardless of how long your ACM2 sat on the self, the ACM2 didn't come into existence until long after the firmware was fixed.

To be thorough, look on the other side too. Pull on the battery wires at the connectors - Gotway has been known to employ poorly qualified solderers. Same with the other connectors. And I know it's a pain in the butt, but maybe cut away the silicon goop on the board connectors to be sure they are seated properly. On one of my ACM's it stopped charging because the crappy solder job at the 4-pin power connector finally finally failed. 

Possible causes

• Firmware - highly unlikely for this version of the wheel
• Intermittent battery connection
• Intermittent cable connection (batteries or connections to the board)
• Intermittent battery cell connection (inside either of the blue battery packs) - this would be a rare problem I would think.
• Intermittent connection inside the motor (hall sensors for power wires to the motor)
• Failing component on the control board, or something else failing on the control board.

I think my first approach would be to disconnect every connection (motors wires are probably OK if they pass the pull test) and tug on the wires to make sure they are good.

Not sure what else to suggest.

[csmyers]

Well, just checking in on this issue to close the case -

There was a connection that was ever so slightly loose. One of the ones bundled up on the left side. I unplugged it and saw the metal contacts were loose as well. I might need to re-solder these but in the meantime, plugging it back in I've had no issues for about 80 miles.

Meanwhile, I finally received my Mten3...

Edited November 1, 2018 by csmyers

[Marty Backe]

15 minutes ago, csmyers said:

Well, just checking in on this issue to close the case -

There was a connection that was ever so slightly loose. One of the ones bundled up on the left side. I unplugged it and saw the metal contacts were loose as well. I might need to re-solder these but in the meantime, plugging it back in I've had no issues for about 80 miles.

Meanwhile, I finally received my Mten3...:)

Thank you very much for this information. @Hunka Hunka Burning Love - I wonder if something like this could have been the cause of your random Tesla event?

Yeah, I was excited when I saw you picked up one of my favorite wheels. Please let me (us) know how you enjoy it 

[csmyers]

@Marty Backe I will! Hopefully I can do an end-of-the-year review on it. With all the attention paid to the new 18" wheels, I think it might be time to bring the Mten3 back to the discussion 

@Hunka Hunka Burning Love I missed the discussion of your Tesla incident - what happened there?

[Hunka Hunka Burning Love]

Here's the post if you're interested. 

It was a routine ride that I've taken many times before.  I crossed the road on a marked crosswalk, and I may have gone a little too fast as a truck was waiting to turn after I went by.  I did a little S arc to go up the sidewalk ramp and before I knew it I think I hit a couple of small one inch sidewalk heaves that made me launch forwards.  I wonder if I may have clipped the stop sign post as well?  If that happened, it was just a glancing skim if anything.  I don't recall the wheel spinning to the right though.  It just sort of was left behind me with me thinking oh oh this is where I'm going to fall in a bad way.  There was no time to run this one off at 22 kph halfway into the fall.

Surveying some of the other injuries people have had on the forums, these shoulder injuries are quite common.  I must have landed on my left elbow which sent the forces up to the shoulder where they wrecked some havoc that is still needing time to heal.  It got better to about 90-95%, but now it seems to be getting a little worse after I stretched my arm to the right to turn a light off.  I might have to go get it checked out.  Maybe some cortisone shots will help.

@Marty Backe it could be a vibration sensitive connection problem that sent me flying.  Hard to say.  I might take it apart in the winter to take a look see.  I don't think I would feel right selling it without double checking to make sure it's "safe" for the next rider.

[Victor Jose Ladero Covelo]

Same problem with the V3, you can see the light in my video, when this happen running fast is really scared

https://www.instagram.com/p/BprhgfhnkmD/?utm_source=ig_web_button_share_sheet

[Hunka Hunka Burning Love]

4 hours ago, Victor Jose Ladero Covelo said:

Same problem with the V3, you can see the light in my video, when this happen running fast is really scared

https://www.instagram.com/p/BprhgfhnkmD/?utm_source=ig_web_button_share_sheet

I think you experienced the "wobbles" or lateral side to side oscillations in your case.  Often it's related to a rider reaching higher speeds and the feedback from nervous legs adding to the problem.  Slowing down usually makes them go away.  The oscillation problem that the OP is referring to is what happened when they first released the MSuper V3+'s to the market.  There was a firmware sensitivity that when a rider hit a bump, the gyro would be thrown off resulting in the wheel trying to "find" its level point so it would tilt forwards and backwards rapidly like a bronco buck.  @Marty Backe has a good video demonstrating this effect which led to a worldwide firmware re-flash which was supposed to solve the problem or maybe it diminished it enough to not happen in most cases.

 

There also was that one Tesla an Asian rider was riding which cut off after encountering a slight dip in the pathway.  It looked like it just shut off completely.  It's hard to draw conclusions from one event, and there are many factors that could have been involved besides firmware bugs.  Unfortunately we're the crash test dummies in most cases so we have do our part in bringing up possible causes for failure to the attention of manufacturers.

Looking at this Tesla crash at 0.25 speed, there was no oscillation...

 

Edited November 2, 2018 by Hunka Hunka Burning Love

[Victor Jose Ladero Covelo]

9 hours ago, Hunka Hunka Burning Love said:

I think you experienced the "wobbles" or lateral side to side oscillations in your case.  Often it's related to a rider reaching higher speeds and the feedback from nervous legs adding to the problem.  Slowing down usually makes them go away.  The oscillation problem that the OP is referring to is what happened when they first released the MSuper V3+'s to the market.  There was a firmware sensitivity that when a rider hit a bump, the gyro would be thrown off resulting in the wheel trying to "find" its level point so it would tilt forwards and backwards rapidly like a bronco buck.  @Marty Backe has a good video demonstrating this effect which led to a worldwide firmware re-flash which was supposed to solve the problem or maybe it diminished it enough to not happen in most cases.

 

There also was that one Tesla an Asian rider was riding which cut off after encountering a slight dip in the pathway.  It looked like it just shut off completely.  It's hard to draw conclusions from one event, and there are many factors that could have been involved besides firmware bugs.  Unfortunately we're the crash test dummies in most cases so we have do our part in bringing up possible causes for failure to the attention of manufacturers.

Looking at this Tesla crash at 0.25 speed, there was no oscillation...

 

Is not new the wheel (I buyed used) probably is the same problem like marty shows, but in flat surface without jumps , Im going to find the firmware thanks

[Chriull]

19 minutes ago, Victor Jose Ladero Covelo said:

Is not new the wheel (I buyed used) probably is the same problem like marty shows, but in flat surface without jumps , Im going to find the firmware thanks

For gotways one cannot change the firmware oneself. You'd need a reseller who has the reflashing hardware or a new motherboard (with the newer firmware on it).

From what i've read it could be hard to find the right revision of a mainboard, since gotway changes the hardware used for their models without versioning the model?