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Random cutoffs regardless of load/speed/battery


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please skip to bottom for potential cause if post is too long for you


I. Intro
Hi all, thank you creating this community. I'm excited to join you, despite having to ask for EUC help with my very first post here. Hopefully my story can help other people or serve as a cautionary tale for anyone who thinks cutoffs only happen because of speed or overleaning. I was lucky with my fall but it could've been way worse.

II. Unexpected first cutoff and fall ~25km/h
I bought my MCM4 (HS 680wh) a month and a half ago second hand ( ~970km) and it served me very well for 200km, until it suddenly cut off without warning nor tilt-back while going around 25km/h. Having read a lot of posts here, I assumed it was user error, maybe an uneven spot on the bike lane, maybe 80% battery wasn't enough for my speed. I was just happy I had a helmet and wrist-guards on, and managed to do a roll, so I only ended up with a slightly sprained ankle and a bit of road rash on my lower back. Until then I had ridden 7kms on that journey and had a pause of 2 hours before heading back and having a cutoff on the second minute of riding. The bike lane it happened on was separate from the road and despite that my EUC went on the road during rush hour. Thankfully there was a traffic jam and also it somehow managed to miss all the nearby cars. Yet, I couldn't help but think about the unsecured bike lanes I rode on shortly earlier that day and what could've happened at the wrong time and place - I'd rather stick to sidewalks and slowing down for curbs and pedestrians. I carefully rode the remaining 7kms home without any further issues.

III. Weird low-speed tilt-back and cutoffs

The following days I had short trips and casually rode around to see if I can trust my EUC after my first no-warning cut-off. Everything seemed normal for a week and just as I had written it off as user error I got some tilt-back while going around 5km/h. It was so unexpected that I thought I'm imagining things but I carefully finished my journey. Yet on the way back, an hour later, after 3 minutes of normal riding it happened again around 10km/h, this time leading to a cut-off after I stepped off, followed by 3 beeps similar to when it has fallen to one side and a 4th beep when it resets. I turned it off for a few seconds and back on and carefully rode home. I think it happened a couple more times for the remaining 2-3kms

The next day everything seemed in order, I spent a good hour or so riding back and forth without issue ... until I went out later the same day. I rode 1km and again got the low-speed tilt-back and unstable floaty balancing. Only this time it kept losing it's balance, cutting off and resetting, even without me stepping on it, just by rocking it back and forth with my hand, in fact I couldn't push it with the trolley without it failing to balance. After I left it for a couple of hours I could at least push it with the trolley so I started wondering if it's something to do with the battery, despite it being around 70%

Today I decided to go out so I can record videos of it failing, as well as to check current, etc in the EUC World app. I rode cautiously while recording video for 10 minutes without it failing. I turned it off for 5 minutes and tried again and this time it did it immediately. I went home, charged it to 100%, went out again and repeated the experiment, with it initially working OK but then cutting off in less than 5 minutes of slow riding.

IV. This doesn't look right??

Spoiler

 

50325063852_9a1ebc245e_b.jpg

 



Since it started consistently failing despite the low speeds and fully-charged battery, I decided to open it up and look for some clues, even though I'm not knowledgeable in electronics. I got the first cover off and immediately saw this. I have no idea which connector is responsible for what, but it looks this one has come undone despite the glue/paste it was covered in.

I would be very grateful for some information and advice:

Should I just plug it in? Should the batteries be disconnected first? Do I have to unscrew the whole board? Do I have to watch out for something else? 

V. Edit/Update

OK, so turns out this connector is for the USB and should be irrelevant. Still looking for a solution.

I haven't checked out the capacitors/etc yet but will look into that.  

No obvious issues with capacitors, mosfets or wires that I can see, at least.

 

Edited by Lateralus
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7 hours ago, Lateralus said:

until it suddenly cut off without warning nor tilt-back while going around 25km/h. Having read a lot of posts here, I assumed it was user error, maybe an uneven spot on the bike lane, maybe 80% battery wasn't enough for my speed

Seems to be plausible for such a wheel to overlean at this speed with some burden.

7 hours ago, Lateralus said:

tilt-back while going around 5km/h

 

7 hours ago, Lateralus said:

happened again around 10km/h,

Beside max speed (when enabled) tiltbacks happen due to overvoltage (downhill regenerative braking) or overheat.

Since you wrote

7 hours ago, Lateralus said:

despite it being around 70%

i'd guess it's overheat alarm? You have an app to see reported temperature?

Here (somewhere) are also the descriptions for alarm beeps, so one could know what the wheel tries to tell one.

7 hours ago, Lateralus said:

Today I decided to go out so I can record videos of it failing, as well as to check current, etc in the EUC World app.

You have video and euc world logs?

7 hours ago, Lateralus said:

but it looks this one has come undone despite the glue/paste it was covered in.

Seems like it was pulled out with force and partly destroyed the plugs side? ..but hard to tell from the photo.

All the pins and their counterparts are existing and in good shape?

7 hours ago, Lateralus said:

I have no idea which connector is responsible for what

Me neither. Does the mcm4 has a fan? Would fit with the overtemp alarm guess, if it exists but is disconnected...

Around here should be enough experienced GW owners to give valuable hints and tipps.

If not, you should open further to reveal were the wire lead to at the other end...

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Thank you for replying!

9 hours ago, Chriull said:

Seems to be plausible for such a wheel to overlean at this speed with some burden. Beside max speed (when enabled) tiltbacks happen due to overvoltage (downhill regenerative braking) or overheat.

I was just cruising at this speed, negligible acceleration and slope, no braking

Quote

i'd guess it's overheat alarm? You have an app to see reported temperature?

I've monitored reported temperature and cutoffs have occurred even under 40°C

Quote

Seems like it was pulled out with force and partly destroyed the plugs side? ..but hard to tell from the photo.

All the pins and their counterparts are existing and in good shape?

I think just the paste was torn apart, the wires and connectors seem in good shape. The sad part is that I'm pretty sure the wires in question lead to the USB port, so it most probably won't be the culprit for my troubles.

Here's one screenshot from after a cutoff at low temps and full battery
50326288517_1901dfbc42_c.jpg

Here's a video from a few nights earlier where it's more obvious. Battery around 70% temp, temp around 40C, virtually no load

 

 

I am wondering if this is relevant but I don't know how to go about checking.


Any other advice is also welcome!

Edited by Lateralus
typo
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16 minutes ago, Lateralus said:

Thank you for replying!

You're welcome.

So no overspeed, no overburden, no overvoltage or overheat - but still a tiltback. Could not think of a valid reason - so some serious fault/malfunction?

Maybe the gyro is gravely misadjusted and a calibration could help?

In the video it seems the wheel is not really balancing at all? Beep codes i found in the table here: 

 

21 minutes ago, Lateralus said:

I am wondering if this is relevant but I don't know how to go about checking.

With a hall sensor failure/broken wires one should not get a tiltback?

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Okay just got back from another test ride.

First some background: I have no idea regarding the hall sensor question. In the video it is balancing but the slightest push makes it cut off. Usually it would work normally for a few minutes, get low speed tilt-back and only then get to the point you see in the video. Beeps seem to be the same you'd get if you dropped it sideways and hence trigger the safety shut down, although it's usually less than 5 if you center it fast enough.

In terms of calibration I was skeptical because I hadn't messed around with it before or after the 1st cutoff/fall and it worked without any issues before that and some time after. Nevertheless I gave it a go, then gently poked around the wires trying to see any visible issues and closed the case without plugging in the cable from the first photo.

I went out expecting to ride for 5-10 minutes and get the usual tilt-back or cut off but instead I spent almost 2 hours, riding over 15km without issues. Granted most of my journey was under 20km/h but I did go over some bumpy roads and pushed it to 24km/s a few times. Now I have no idea if the calibration fixed things or I accidentally adjusted some dodgy wire/connector :| Not sure how I can get to know for certain, as I don't feel like playing Russian roulette every time I ride.

At the very least I'll go out for more testing and report back but your thoughts are very welcome!

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Unfortunately during the latest test ride it happened again 2 minutes in, low speed, flat road, no crazy acceleration or braking. I did carry on for 3-4km without additional issues, though. I can't seem to come up with something that consistently triggers it nor something that fixes it.

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Pull the board out and check the condition of the capacitors. A friends MSX had very similar issues. It cut out during a mild ride, powered back on after - rode again - up to 15mph, no problem, but cut out again shortly after - turned back on - balanced fine - decided not to ride it anymore. Turned out the caps were very swollen. New board - zero problems.

The above is only likely to happen on a well used wheel but I have no idea how used yours is. My friend had 6k miles on his.

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I brought it to my father who has more experience dealing with electronics and we checked for anything suspicious but found nothing, no damaged wires or swollen capacitors for example.

We put it back together and I went for a test ride, but it did the same thing in 1-2 minutes of riding, after which I rode for 5 minutes with no issues, then I went home and took it for another test. Again it did the low speed weirdness + tilt-back, but once it recovered I rode 12km without issues, even pushing it to 27km/h as well as up a steep ramp.

At this point I am considering a new board if I can find one, but how do I know it's not something to do with the motor hall sensors for example?

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Can anyone help out with diagnostics, spare parts or advice? I can't find any place that has replacement controllers for the mcm4, not even second-hand, if that's even a solution, since the wheel usually works without issue...until it randomly either starts losing balance, tilting back or suddenly falling over. Know someone with experience? @evil696?

I miss riding and having fun, and it's my only wheel. Probably can't even sell it for spare parts unless I know what works fine and what doesn't.

Edited by Lateralus
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On 9/11/2020 at 1:40 PM, Lateralus said:

At this point I am considering a new board if I can find one, but how do I know it's not something to do with the motor hall sensors for example?

Given it is an intermittent problem testing hall sensors would not appear to reveal much unless wheel is in fault condition which appears to be difficult to trigger. Nevertheless if you decide you wanna test them you can do so without much tear down:

no you cannot sell it.  Given problem is intermittent makes it hard to troubleshoot. Try to find someone local with this euc and swap the motor - that will soon show if board or motor. if was hall sensor issue new board would not solve anything (unless the failure is at the interface on the board (unlikely)) - but there are some on the forum with much better debugging skills. 

Not fun when you really cannot ride safely :-(

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Thank you for the suggestion and the empathy! Might as well figure out how to test the hall sensors/wires/connectors, since I can't find a controller. As for finding another mcm4 locally - chances aren't too good, since there's give or take 100 EUC users in the whole country, and it's a pretty old model.

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I'm guessing it's gyro related. The calibration can help to a certain degree but if the readings it puts out are all over the place it will occasionally trigger overlean cutoffs.

I've never had my used tesla gen1 cut out on me but I have experienced weird gyro behavior. When initially trying to get the pedal angle right, which on gotways is a pain to set compared to other brands, I had my wheel once or twice calibrate erroneously. Usually in very cold temperature, which I noticed later. By erroneously I don't mean it gave me an error. It just behaved super weird.

It seems that if the gyro puts out excessively weird data when calibrating the settings become screwed up. The result for me was that I got severe tiltback with a full battery at already 2km/h or thereabout. The machine was unrideable until I carried the thing home and did a warm calibration. Then it came back to normal.

Another symptom of a bad calibration was that the (sideways) overlean cutoff occurred at different angles left/right. I could by hand lean until the pedal touched the floor on one side without shutdown, but not the other side. That's not normal.

If your gyro is screwed up a new board will probably fix it. I'd try a warm room temperature calibration first. Do the tests mentioned above.

After doing a warm calibration I've never had the tesla behave oddly on me, even when riding in freezing temperatures. What you never must do is calibrate away from home because you could end up walking home.

What I don't like about the tesla now after a few thousand km, is only that the pedals dip forward when going over bumpy surfaces. I've learned to live with it but it scared the hell out of me in the beginning before I found the right angles, and found my favorite grip tape to put on the pedals. The original grip tape is atrocious. I use skateboard "golden sand" type now and it lasts forever. Super cheap too. I got my pedals angled up 5 degrees. On my previous inmotion they  were nearly flat 0deg, but that didn't dip forward like the gotway.

Make sure that your control board is bolted down properly inside the machine. It can't be moving around. Usually the wheel shakes when that's the case which yours doesn't but it's never a bad idea to check just in case.

Are you sure you have a healthy battery pack? Check for corrosion or loose terminals. Puffed cells or hot temperatures after charging or riding.

Edited by alcatraz
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Some exciting development! I've finally had some success finding some correlation that is repeatable although not 100% consistent. Things are pointing towards a cable and/or connector issue. I had opened it up with the power on, to investigate, mainly focusing on the hall effect wires and luckily it went into a continuos fail->reset->fail loop. This time I had removed the motor cable from its groove, which has a bend at one spot. I decided to twist it around a bit and managed to stop the fail loop. Upon letting go it started failing again. I wondered if it's just a coincidence since I couldn't always make it fail or stop failing but after some attempts it became very hard to downplay the correlation as you can see in this video:

Spoiler


This is what the cable looks like because of the bend:

50382428071_df935db609_c.jpg

 

I did a few more tests and started wondering if it is actually the hall wires but it's hard to determine exactly where the point of failure is. In this video it was again in a fail loop until I pushed slightly on the hall connector being careful not to move the whole motor cable.

Spoiler


As you see, however, poking around to trigger a failure didn't make a difference. I will have to investigate further, since I am immediately posting this, and it stopped failing regardless of me moving the cables around.

 



All in all, though, would you agree things are pointing towards cable issues? I won't be making any repairs on my own, but I'll have to research what is required so that it is done properly and I can hopefully get a safe reliable wheel.

EDIT: Definitely pointing towards hall sensor connection issue

 

Edited by Lateralus
Added new video
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im assuming the wiring near the mother board was zip tied and not free to move around (when you are done your debug/fix you should for sure zip tie and solidify so that the wires are not moving around close to board as this can induce problems by stressing connectors etc)- but if by moving cables you are triggering failure modes then certainly points to a cable/connector issue  (fraying, broken insulation, shorts, etc. ) - isolate from the motor working back to the board being careful to move only the section of interest and if you lucky you will find the trbl spot.

Edited by amelanso
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