Marty Backe

The Gotway Gods Destroyed My ACM

210 posts in this topic

Sorry to hear this:( But seeing the video (great video btw:thumbup:), it was inevitable this would happen.

This is 100% deja vu for me. The sudden cut out on slow hill driving, the inspection of the damage back home, exactly the same result (well I didn't blow a mosfet but the board had to be replaced anyways).

I think what you didn't mention much was the massive heat damage at the end of the big black sleeve holding all cables from the motor together. Probably a weak point if you don't replace the motor. I had exactly the same. Also, it seems the location where the cables fuse together is more or less random (maybe due to some inhomogenities in a cable). I believed it was due to the cables being bent and especially vulnerable (as mine melted where they bent coming from the sleeve), but apparently that was just a coincidence.

This is good motivation to finally have to make my last mountain test (checking currents on a certain damn incline) and then I can write it all up.

--

Can you give a location on Google Maps of your route so we can check the inclines and see how long they were? You didn't by chance have Wheellog logging?:P

Also I recommend you get one of the new motors, probably you'll have to replace yours anyways, due to that heat damage.

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Glad you are fine from your fall marty. You are right that all the examples of Gotway wheel's wires melting and/or MOSFETs burning up are on very steep extended inclines. If Gotway or any other wheel just cannot do the incline because of overheating or other issues, then you should expect them to alert you somehow just like the Monster did with tiltback. I expect any Kingsong wheel to do the same. We should NOT be able to keep riding until complete failure.

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4 minutes ago, meepmeepmayer said:

Sorry to hear this:( But seeing the video (great video btw:thumbup:), it was inevitable this would happen.

This is 100% deja vu for me. The sudden cut out on slow hill driving, the inspection of the damage back home, exactly the same result (well I didn't blow a mosfet but the board had to be replaced anyways).

I think what you didn't mention much was the massive heat damage at the end of the big black sleeve holding all cables from the motor together. Probably a weak point if you don't replace the motor. I had exactly the same. Also, it seems the location where the cables fuse together is more or less random (maybe due to some inhomogenities in a cable). I believed it was due to the cables being bent and especially vulnerable (as mine melted where they bent coming from the sleeve), but apparently that was just a coincidence.

This is good motivation to finally have to make my last mountain test (checking currents on a certain damn incline) and then I can write it all up.

--

Can you give a location on Google Maps of your route so we can check the inclines and see how long they were? You didn't by chance have Wheellog logging?:P

Also I recommend you get one of the new motors, probably you'll have to replace yours anyways, due to that heat damage.

Thanks :cheers:

I'm really hoping not to replace the motor. That's a task I would rather not undertake. I'm fine with not being able to climb super steep hills.

I did peel back that sleeve further up the motor cabling and found a couple of the very small wires semi-melted to a motor cable. I think you are right - the cables can melt anywhere - I'm lucky they melted far from the axle.

I will post the Google Earth track and you'll see exactly the grade that killed the ACM.

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@Marty Backe

Thank God nothing happens to you!! Thats the most important here!

Imagine going a steep hill with much more speed and than cutting out! The wiring realy sucks on the Gotways...they really dont seam to have put a lot thoughts in it. exactly what happends to @meepmeepmayer s wheel.....

And: YOU are a very lightweight person, so depending on hill and persons weight that can happen even further...

What are the new connectors helping than in anyway if the heat that is generated melted down the complete wiring?

And that on a place where they are more or less loosly together, i will not know what happends inside the axle where they are squeezed.....

So your conclusion is correct: no excessive hills on a Gotway, if you want your health stay as it is....

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2 hours ago, Mrd777 said:

Marty this is quite an amazing video, thanks for sharing all this. I think we have learned a lot. Hopefully Gotway is paying attention, obviously larger gauge wire is needed.

For now I will keep the hills to a minimum on my ACM. Glad you are ok

They already (due to @Jason McNeil's precautionary lobbying) went from 16AWG (~20A sustained current as per spec) to 14AWG (~30A sustained current). @Marty Backe's wheel is the 20A old motor cabling. But even the thicker wiring isn't nearly enough, this hill easily did 50A or more (more exact numbers after my final testing). And probably the mosfets may have blown soon after had the cables lived (just some pessimistic speculation).

2 hours ago, Marty Backe said:

But any hills were you can be cruising at 5+ mph should be fine.

I would not be so sure (though you have plenty of mountain experience, and know which inclines work). It's the current, you have to check yours. Too high current will slowly but surely melt the cables if the heat can't disperse. This incident just seemed to happen quite fast, but you can have the same problem, but slower. The million $ question is, which current is actually too much so that the heat collects until it melts something. Hopefully I can give some indication after more testing.

1 hour ago, Hunka Hunka Burning Love said:

1.  Don't climb steep hills for extended periods of time without cooling down sessions every now and then.

This is exactly the right thing to do. Know which incline for how long will not heat-damage your electronics (no melting, just damage), and take breaks accordingly.

1 hour ago, Marty Backe said:

The Monster runs about 10 degrees c hotter than my ACM and MSuper. So it makes sense that Andy's Monster stopped before my wheel overheated (which is never did - but the cables melted - a subtle difference).

Yea it is pure design-luck that the Monster overheats before anything melts. Same basic principle applies.

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5 minutes ago, Michael Vu said:

Glad you are fine from your fall marty. You are right that all the examples of Gotway wheel's wires melting and/or MOSFETs burning up are on very steep extended inclines. If Gotway or any other wheel just cannot do the incline because of overheating or other issues, then you should expect them to alert you somehow just like the Monster did with tiltback. I expect any Kingsong wheel to do the same. We should NOT be able to keep riding until complete failure.

Agreed. Gotway could do this with the current sensors, but first they must have a proper wiring harness.

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Posted (edited)

3 minutes ago, Marty Backe said:

I'm really hoping not to replace the motor. That's a task I would rather not undertake. I'm fine with not being able to climb super steep hills.

I did peel back that sleeve further up the motor cabling and found a couple of the very small wires semi-melted to a motor cable. I think you are right - the cables can melt anywhere - I'm lucky they melted far from the axle.

If the damage is already beginning in the sleeve, just a question of time before it's too much. I would not trust the old motor, unless you strictly stay off virtually any inclines in this vulnerable state.

Might be worth contacting Ian, as you got the wheel from him. Maybe you'll get some free parts (motor and board, ideally);)

Edited by meepmeepmayer
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1 minute ago, KingSong69 said:

@Marty Backe

Thank God nothing happens to you!! Thats the most important here!

Imagine going a steep hill with much more speed and than cutting out! The wiring realy sucks on the Gotways...they really dont seam to have put a lot thoughts in it. exactly what happends to @meepmeepmayer s wheel.....

And: YOU are a very lightweight person, so depending on hill and persons weight that can happen even further...

What are the new connectors helping than in anyway if the heat that is generated melted down the complete wiring?

And that on a place where they are more or less loosly together, i will not know what happends inside the axle where they are squeezed.....

So your conclusion is correct: no excessive hills on a Gotway, if you want your health stay as it is....

Totally agree @KingSong69. The connector issue may be resolved, but they need a total rethink on their wiring harness design. I used to think it required a heavier person, but I'm 170 pounds, not very heavy (I think). So no more super steep hills for me. If I find myself struggling to keep any of my Gotway wheels moving, I'm going to stop and walk the wheel.

Maybe in a few years this will all trickle down to Gotway and their wiring will be A+ (or maybe just A) :efee47c9c8:

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Posted (edited)

11 minutes ago, Michael Vu said:

If Gotway or any other wheel just cannot do the incline because of overheating or other issues, then you should expect them to alert you somehow just like the Monster did with tiltback.

Yep that's the most frustrating thing. This should be 110% basic functionality of any wheel. They already can read all the necessary wheel data. They just don't know which numbers are ok and which are not themselves!

Monster is just a lucky design, apparently it overheats before anything melts.

Edited by meepmeepmayer
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8 minutes ago, Marty Backe said:

I used to think it required a heavier person, but I'm 170 pounds, not very heavy (I think). So no more super steep hills for me. If I find myself struggling to keep any of my Gotway wheels moving, I'm going to stop and walk the wheel.

Lifting power for incline is linear in mass. So a lighter person will have the same thing, the incline will just be respectively higher. But in principle it can happen to anyone, no matter the weight.

Also, again, overheating is overheating, it may just go slower or faster depending how steep. Be aware of that. The only safe hills/inclines are the one you tested and worked without any damage to the wheel.

6 minutes ago, Marty Backe said:

I have an e-mail to Ian to see what he charges for a control board. God, I really don't want to undertake the surgery required to replace the motor. And the cost???

Hard to ask Ian for any favors since climbing steep hills is probably outside of warranty. AndI don't want to abuse the relationship with Ian - he's a good guy :thumbup:

Motor is virtually same price as the board, so not that bad. Also, surgery, you already need to re-solder the connections, which is the hardest part. Changing the motor with it should be not too much extra work.

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41 minutes ago, Marty Backe said:

I have an e-mail to Ian to see what he charges for a control board. God, I really don't want to undertake the surgery required to replace the motor. And the cost???

Hard to ask Ian for any favors since climbing steep hills is probably outside of warranty. And I don't want to abuse the relationship with Ian - he's a good guy :thumbup:

There's that myfunwheels.com guy in Brentwood, very local to you.  And recommended by a couple of people on the forums that I've seen.  Perhaps he can do the job if you don't want to .. or at least be a source for parts, or even just some feedback on the project.

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3 minutes ago, Dingfelder said:

There's that myfunwheels.com guy in Brentwood, very local to you.  And recommended by a couple of people on the forums that I've seen.  Perhaps he can do the job if you don't want to .. or at least be a source for parts, or even just some feedback on the project.

Yeah, Dion's a great guy. I bought two ACM's from him last year. Brentwood is a few hundred miles away.

I'll do the work if I must, but I'd rather be riding than rebuilding my wheel :(

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It's all about product specification and to keep the device in this figures. Thresholds, thresholds,..

What wound have happens downhill with speed and massive breaking? 

Are this devices are safe to ride? I would like to point towards the sentence safety. 

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Posted (edited)

2 hours ago, meepmeepmayer said:

Sorry to hear this:( But seeing the video (great video btw:thumbup:), it was inevitable this would happen.

This is 100% deja vu for me. The sudden cut out on slow hill driving, the inspection of the damage back home, exactly the same result (well I didn't blow a mosfet but the board had to be replaced anyways).

I think what you didn't mention much was the massive heat damage at the end of the big black sleeve holding all cables from the motor together. Probably a weak point if you don't replace the motor. I had exactly the same. Also, it seems the location where the cables fuse together is more or less random (maybe due to some inhomogenities in a cable). I believed it was due to the cables being bent and especially vulnerable (as mine melted where they bent coming from the sleeve), but apparently that was just a coincidence.

This is good motivation to finally have to make my last mountain test (checking currents on a certain damn incline) and then I can write it all up.

--

Can you give a location on Google Maps of your route so we can check the inclines and see how long they were? You didn't by chance have Wheellog logging?:P

Also I recommend you get one of the new motors, probably you'll have to replace yours anyways, due to that heat damage.

Attached is the Google Earth track for our ride. The failure happened at the end (far left of the trace). When you view the elevation profile you can see the steepness of that final climb (max of 27% slope). Here's a screenshot too

https://www.dropbox.com/s/ck7h9g4rm8ymq0y/Chino Hills Hill That Killed ACM - 18Jun2017.jpg

 

 

Chino Hills State Park - 18Jun2017.kmz

Edited by Marty Backe
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Posted (edited)

I think the new motors have the thicker gauge wiring so hopefully they won't melt under heavy duty load?  This has yet to be tested though, but that's the working theory.  Also with matching gauge wiring there should be less resistance at the connection junction hopefully.  Gotway also eliminated the melting black caramel (;)) plastic connector covers so maybe also using the clear plastic sheaths or a heavier duty one like Rehab did might help if they have a higher temperature tolerance.

Yes, I know, that is a lot of if's and assumptions, but I was hoping to restore some of the man's faith as the Gotway gods just let him down.  Plant some seeds of hope, and sometimes good things can come of it (unless you're in an Alien Covenant movie in which case you are majorly screwed).  :innocent1:  Marty's been Gotway's number one advocate and prosyletizer.  We can't have him doubting the brand's potential for improvement now, can we?  Couldn't you tell how disappointed he was in the video?

Edited by Hunka Hunka Burning Love
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Posted (edited)

2 hours ago, Hunka Hunka Burning Love said:

I think the new motors have the thicker gauge wiring so hopefully they won't melt under heavy duty load?  This has yet to be tested though, but that's the working theory.

Is that so?

I only heard they changed the connectors (more than one time). But to use thicker wires on the Motor side would require a complete new axle design, as thicker wires are not going through the axle at the Moment (Ok, rehab managed to do that, but not in a production process....and nearly strippping the thicker wires) So i think that is more wishfull thinking ....that they completly redesigned Motor/axle etc....

But who knows? Maybe?

Edited by KingSong69
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8 hours ago, Marty Backe said:

...

The ride started nicely enough but we eventually started on the dirt and gravel trails. During on epically long very steep section Andy's Monster overheated with a resulting tilt-back, and within 5 seconds my ACM self-destructed. It was a long hike out :(

In this video (thanks Andy for all the additional video footage) you can see the ride and where I crash and burn as the ACM gives out on me. Then, back in my workshop I open the ACM and show the carnage inside (massive amounts of melting connector housings and wires. Oh, and the control board is toast.

Seeing the melted wires first hand (and my riding weight is 170 pounds) tells me that I will never again (until they make design changes) ride any of my Gotway wheels for extended (>15 seconds) periods up very steep hills. It's clear that the insulation isn't up to the task. Mind you, I'm talking very steep hills, where you are crawling up.

With the mentioned ~27% slope bringing up 100kg at ~10 km/h results in ~730W potential energy needed. With air drag and rolling resistance something about 800W.

With ~60V Battery Voltage that should result in a current of ~13A.

To melt the cables something >20-40A should be needed? So more than 2-4 times this power. Seems like slow EUC driving (at least uphill) beeing very inefficient... ;(

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So, I wonder how EUC manufacturers come up with the motor maximum power specification?   Is it just the maximum power rating for the motor and not for the rest of the circuitry (including wire)?

Is that a continuous power specification, or just "max instantenous power"? At what ambient temperature?

And, there's not protection to (tilt back or beeping) to prevent damage like this?  When the battery voltage decays, it takes more current to deliver the same power.  Which means more heat.  The increased current causes more voltage drop in the motor windings and in the wire interconnects.  Then, still lower voltage.  Which means more current.  

 

It's surprising there's not protection for that, like tiltback when a low pass filtered analog of the current exceeds a certain threshold.  Maybe just a dumb mistake where the designer(s) didn't realize the wire Marty pointed out was the weakest link.

Thanks for posting!

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1 hour ago, Chriull said:

With the mentioned ~27% slope bringing up 100kg at ~10 km/h results in ~730W potential energy needed. With air drag and rolling resistance something about 800W.

With ~60V Battery Voltage that should result in a current of ~13A.

To melt the cables something >20-40A should be needed? So more than 2-4 times this power. Seems like slow EUC driving (at least uphill) beeing very inefficient... ;(

Where do you have those numbers from?

From my experience -carefully watching the app stats with amps and Watts- on my V3 i can easily come over 30 or  40 Amps even when on not so steep hills....(both gyrometrics and darknessbot)

When i had my fall on KohTao, blowing the 40Amp Fuse (with a broken capacitor), that also has not been such a steep hill.....but enough to take a load of 40 Amps.

When i consider the ACM having a 20s6p System, where each System is able to deliver at least 10Amp, so 60Amp in total, in Peaks even maybe higher?!, i can guess that those max Amps are used from the Gotway Board on extreme situations.....

 

That's no offense by any means, but "just" 800Watt on such a steep hill?

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30 minutes ago, DaveThomasPilot said:

So, I wonder how EUC manufacturers come up with the motor maximum power specification?   Is it just the maximum power rating for the motor and not for the rest of the circuitry (including wire)?

Is that a continuous power specification, or just "max instantenous power"? At what ambient temperature?

That's something imho noone really knows by now... or happened to calculate and design properly... :wacko:

30 minutes ago, DaveThomasPilot said:

And, there's not protection to (tilt back or beeping) to prevent damage like this?  When the battery voltage decays, it takes more current to deliver the same power.  Which means more heat.  The increased current causes more voltage drop in the motor windings and in the wire interconnects.  Then, still lower voltage.  Which means more current.  

The motor does not really "need battery power". 

The torque of the motor is proportional to the current. The "forward force" is proportional to the torque. The motor power is force time speed.

So there is fortionately no feedback loop with the battery voltage and battery power.

Just max speed is limited by lower battery voltage (due to high currents).

30 minutes ago, DaveThomasPilot said:

 

It's surprising there's not protection for that, like tiltback when a low pass filtered analog of the current exceeds a certain threshold.  Maybe just a dumb mistake where the designer(s) didn't realize the wire Marty pointed out was the weakest link.

They could introduce line circuit breakers as used in our homes to secure the wires...:ph34r:

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8 minutes ago, KingSong69 said:

Where do you have those numbers from?

From the formula for the potential energy Epot=m*g*h. The needed Power is then P = m * g * delta h / delta t = m * g * v_vertical

8 minutes ago, KingSong69 said:

From my experience -carefully watching the app stats with amps and Watts- on my V3 i can easily come over 30 or  40 Amps even when on not so steep hills....(both gyrometrics and darknessbot)

When i had my fall on KohTao, blowing the 40Amp Fuse (with a broken capacitor), that also has not been such a steep hill.....but enough to take a load of 40 Amps.

When i consider the ACM having a 20s6p System, where each System is able to deliver at least 10Amp, so 60Amp in total, in Peaks even maybe higher?!, i can guess that those max Amps are used from the Gotway Board on extreme situations.....

 

That's no offense by any means, but "just" 800Watt on such a steep hill?

High peaks are mostly from (strong) accelerations. But in average for something with 100% efficiency these 800 Watt suffice to bring 100kg up a 27% incline with 10 km/h.

So this brought me to my conclusion "Seems like slow EUC driving (at least uphill) beeing very inefficient... ;("

Ps.: Imho once was mentioned by one of the GW representatives here that GW has implemented a 120A high speed electrical current limiter to protect the circuitry/battery/motor while at slow speeds/standstill.

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7 minutes ago, Chriull said:

From the formula for the potential energy Epot=m*g*h. The needed Power is then P = m * g * delta h / delta t = m * g * v_vertical

High peaks are mostly from (strong) accelerations. But in average for something with 100% efficiency these 800 Watt suffice to bring 100kg up a 27% incline with 10 km/h.

So this brought me to my conclusion "Seems like slow EUC driving (at least uphill) beeing very inefficient... ;("

Ps.: Imho once was mentioned by one of the GW representatives here that GW has implemented a 120A high speed electrical current limiter to protect the circuitry/battery/motor while at slow speeds/standstill.

In my 40Amp Fuse blow "Case" i have not been able to drive faster...i felt that the wheel was on it's "borders"....

So i would say that an acceleration at low Speed against a given obstacle - here a steep hill - also draws high Peaks.....

 

Yes, i have heard of this 120Amp current limiter also, but wasn't it even set higher on the 84 Volt models? I guess/remember @zlymex brought up such numbers and also that the amperage running through one Motor Phase can even be as high as this current Limit... ( or similar like that it was explained...Sorry...dont have it on my mind any more)

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