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Gotway ACM just died @ 30kph+


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Yup. My 1.5 week old Gotway ACM just gave out at over 30kph... sending me flying. Had been riding for about 15 mins or about 3-4 miles on pavement and then gave it gas going uphill north of 30kph and then it just died. It went down, then I went down. Thankfully, I was wearing full pads and helmet but am a great deal scraped up. I had some foam padding on the ACM that at least helped protect it a little as well. 

Two questions, in case anyone knows the answer:

1) Is this failure a common problem with the ACM? If so, what causes it -- as I will not want to go through that again if I can help it. 

2) The tire now rubs internally at various spots on the rotation. Guessing parts are bent/stressed from being bounced around. Other than taking it all apart and trying to put it back together again is there any other cure I should consider first?

Any advice some any of the much greater riders than me in the forum would be GREATLY appreciated!

Thanks,

J
 

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@EU_Newbie hmmmm, not a lot to go on here.

  1. Where is your ACM from (dealer)? Is it new or used?
  2. What version ACM is this, 67V or 84V?
  3. What is your skill level or month(s)/year(s) riding EUCs?
  4. What was the battery levels when you started and crashed?
  5. How hard were you accelerating?
  6. Was the wheel still powered on when you went to go pick it up post crash?
  7. Did you hit anything, bump, etc, before you went down?
  8. Was there any oscillation / vibration when traveling high speeds before going down?
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i can go on with that list:

 

9. it really doesnt run smooth now anymore?

10. it is scratching against the shell now alltime?

if 9/10 are true...i would guess you have a -seldom- collapse of the axle or so...and now your wheel is defect and not good to go anymore!

but: We need more informations.....

 

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So many questions. I think once you've provided more information we can probably help

  • How steep of a hill? I will say that 30km/h up a hill (depending on the hill) can consume lots of power. When the wheel has no more power to give, it stops balancing. I myself avoid hard accelerations (or excessive speeds) when going up hill or down hill.
Edited by Marty Backe
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3 hours ago, EU_Newbie said:

...

1) Is this failure a common problem with the ACM? If so, what causes it -- as I will not want to go through that again if I can help it. 

This quite presumably is no failure of the wheel - just an non advertised intrinsic property of each electronic motor: the higher the load (acceleration, going uphill) and/or the lower the battery voltage (roughly left capacity) the lower the maximum possible speed.

Gotway advertices maximum speed for quite low load with full batteries - one has to adopt this downwards depending on load and battery state to still drive safely.

Also other more restrictive wheels like the ks16b can be brought to an overlean (from most people called cut-out) without any prior warning: 

This intrinsic characteristic of electric motors leads to all the questions of the other posters here in this topic - to "reveal" if it was a "normal" behaviour of the wheel (which a new driver normaly does and cannot  know anything about - even if one would read the manual...) or really some failure ...

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2) The tire now rubs internally at various spots on the rotation. Guessing parts are bent/stressed from being bounced around. Other than taking it all apart and trying to put it back together again is there any other cure I should consider first?

Unfortionately  the wheels are not designed to take crashey at this high speeds. If you had good luck its just bend plastics of the cover which rubs - if you had bad luck it is, as already mentioned a "bend" axle or metalic frame part. The second case has to be replaced, for a plastic cover problem some tinkering should be sufficient.

Quote

Any advice some any of the much greater riders than me in the forum would be GREATLY appreciated!

Thanks,

J
 

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Isn't all 680Wh models 67V?

Overall, sounds to me you've exceed the performance limits of a properly-working wheel.

I was a newbie once, made the same mistake. Push as hard as usual on a weak 130W-motor China-imitation Airwheel X3 with only 1 bar of battery left, and it dumped me hard!

Edited by Meng Yang
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Sounds like overcurrent limit was hit. Could either be the motor controller or battery BMS current limit. At lower speeds the battery does not have to supply much current to generate large amounts of current in the motor. At 10km/h if 30 amps of current is needed to stay upright the motor controller takes 70V 10A from the battery and converts it to 23V 10A. Running close to full speed the motor requires the entire 70 volts or so, if it needs 30 amps to stay upright the battery will have to supply that much current.

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1 hour ago, EU_Newbie said:

What version ACM is this, 67V or 84V?

  • It is a 680wh

 

 

1 hour ago, Meng Yang said:

Isn't all 680Wh models 67V?

...

So then according to http://airwheel.ru/test-monokoles-na-dinostende/ it should have ~2,3kw peak output power and about comparable to the KS16b/c with 2,2 kw peak?

1 hour ago, EU_Newbie said:
  1. What was the battery levels when you started and crashed?
    • Battery at the start of the ride was 100%. After the crash it is sitting at 90%. BUT, digging deeper into the settings I found that the wheel now thinks it only has 2.4km on it for miles ridden... about the distance back to house after the wreck plus a test run. This might imply a total reset of the system.

So battery was quite full and by this you had the "chance" to go faster at the accident - with a lower battery you would have fallen at lower speeds...

1 hour ago, EU_Newbie said:
  1. How hard were you accelerating?
    • Very hard. About as hard as I have ridden it. 

...

 

  1. How steep of a hill? I will say that 30km/h up a hill (depending on the hill) can consume lots of power. When the wheel has no more power to give, it stops balancing. I myself avoid hard accelerations (or excessive speeds) when going up hill or down hill.
    • About 20 degrees. This is sounding to me like the issue. And this is clearly good / important advice.

So there seems to be no fault with your wheel - you just pushed it as hard as one could and reached the limits...

1 hour ago, EU_Newbie said:

...

Hopefully that provides enough context. I'm wondering if it is simply never OK to push it hard, level ground or otherwise? Thanks for all the helpful comments and questions. Any other thoughts are welcomed. 

J

If you look at the graph at my before posted link (http://forum.electricunicycle.org/topic/7855-anatomy-of-an-overlean/#comment-107721) and look at the the violet, green and red lines (max values for...) these show the limits. You can push your wheel as hard as you like as long as you stop within the limits ;)

(of course this graph is for another wheel, but it should give an rough idea...)

Just in the low speed high current region you could melt some cables or overheat your wheel if you push it for too long.

 

 

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Thanks for the detailed description.

As far as I know their is neither a max current nor a low voltage cut out in the Gotway controllers or battery packs respectively.
So this might have been not a cut out but a typical overlean situation. That is, at a given UPM and voltage, there is a max current and torque. If you lean in any further, there's nothing left to balance you, as current/torque cannot be increased.

There is some controller board algorithm to warn you (warning beep) if you get close to that level, but if you lean in abruptly that might be not triggering quick enough.

If you run some time with high current and low efficiency (and warning beep) the wheel will overheat, and cut out the current to prevent hardware damage. The temp sensor might be part of the cut-out algorithm, but I am not aware of a precise test to further investigate that. As efficiency is low at low UPM, this usually happens on excessive hill climbs. If your wheel did run too hot, that might have been a cut out.

But I have not read of a reset in overlean or cut out situations. Maybe if the voltage did go down unter a certain limit it resets?

Edited by caelus
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My sympathies. I like the way this forum doesn't doggy pile you, possibly because we have all done the "over lean at max speed going up a hill" at least once. Or in my case, twice now, and I knew better and still did it.

I cannot ever tell when my wheels are approaching their limits. I'd suggest manufacturers make one's wheel sound rougher the closer the limits are reached, as those are queues we are used to.

For example, making the wheel skip or misfire as it gets up there in wattage, not enough to dump the rider but to provide tactile and audio feedback to slow down. Wheels should sound strained as they go faster instead of being one smooth power delivery until, suddenly, they aren't. Crash! 

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19 minutes ago, LanghamP said:

My sympathies. I like the way this forum doesn't doggy pile you, possibly because we have all done the "over lean at max speed going up a hill" at least once. Or in my case, twice now, and I knew better and still did it.

I cannot ever tell when my wheels are approaching their limits. I'd suggest manufacturers make one's wheel sound rougher the closer the limits are reached, as those are queues we are used to.

For example, making the wheel skip or misfire as it gets up there in wattage, not enough to dump the rider but to provide tactile and audio feedback to slow down. Wheels should sound strained as they go faster instead of being one smooth power delivery until, suddenly, they aren't. Crash! 

Good idea. Or perhaps a built-in limiter of some sort that won't allow you to push it past it's breaking point along with the audio feedback to let you know that's what's happening. Even if it has to be conservative and you loose a bit of top end, I would gladly trade that off for taking another spill. IMHO should be a feature -- and maybe allow an override switch for crazy people.

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4 hours ago, caelus said:

If you run some time with high current and low efficiency (and warning beep) the wheel will overheat, and cut out the current to prevent hardware damage. The temp sensor might be part of the cut-out algorithm, but I am not aware of a precise test to further investigate that. As efficiency is low at low UPM, this usually happens on excessive hill climbs. If your wheel did run too hot, that might have been a cut out.

Did you even just read my 2-3 answered post to you about "heat cutout" in the other thread? begging you to forget this overheat nonsens?

Again, one last try:

If the wheel gets to warm you get a warning beeps, a long time before the heat will lead to problems beeps triggered by the temperature sensor will occure, and if you ignore these you will get tiltback and not be able to drive anymore. if you are stupid enough to ignore these also, then your mosfets will burn, but a wheel will not cutout because of to much heat!!!!

Even the steep hill problems, you might have read (a part of the thread only as it seams), have nothing to do with heat problems. Here the amps were so high that the current burned the wites, and that because of a misdesign of the Acm/msuper wires and/or onnectors, then typically a short occured because of melted wires/connectors. But that also is no cutout because of "heat problems"!

Edited by KingSong69
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8 minutes ago, meepmeepmayer said:

Yea, if it's just an overlean, why wasn't there the 80% alarm?

Believe it or not, the 80% alarm on the GW's (at least on my V3) isrelative hard coded alarm at about 36-38kmh!

Has nothing to do with current or torque...Gotway just calls it the "80% alarm".

I answered both Linnea and Jane when i received my V3 in October 2016 and they both said its not batterie/ amps or torque related....

My experience with it says the same, i only get it on 36/37 kmh...but never on crazy hills at 25-33kmh or so.....

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5 minutes ago, KingSong69 said:

If the wheel gets to warm you get a warning beeps, a long time before the heat will lead to problems  warning beeps triggered by the temperature sensor will occure, and if you ignore these you will get tiltback and not be able to drive anymore. if you are stupid enough to ignore these also, then your mosfets will burn, but a wheel will not cutout because of to much heat!!!!

Even the steep hill problems, you might have read (a part of the thread only as it seams), have nothing to do with heat problems. Here the amps were so high that the current burned the wites, and that because of a misdesign of the Acm/msuper wires connectors, then typically a short occured because of melted wires/connectors. But that also is no cutout because of "heat problems"!

Thanks for this KingSong69. Makes sense that this is not due to too much heat as you are saying. I believe it was ultimately overlean combined with not paying due attention to the 80% alarm that did it. Thanks for taking the time to reply - much appreciated. J

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Going up a 20º slope at 30km/h with an 80kg rider plus 20kg wheel needs 2700W only for lifting the weight against gravity, plus about 500W to maintain speed. Just saying. 

BTW, 20º means means 36% slope.

Pente-Slope_--Degres-Ratio_V1.jpg

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14 minutes ago, KingSong69 said:

Believe it or not, the 80% alarm on the GW's (at least on my V3) isrelative hard coded alarm at about 36-38kmh!

Has nothing to do with current or torque...Gotway just calls it the "80% alarm".

I answered both Linnea and Jane when i received my V3 in October 2016 and they both said its not batterie/ amps or torque related....

My experience with it says the same, i only get it on 36/37 kmh...but never on crazy hills at 25-33kmh or so.....

This better be true only for the older models!!!!!:furious:

@Marty Backe Since you only use the 3rd alarm on your Gotways, can you tell if they always occur at the same speed, or not and thus are in some way power/torque/battery-related?

Edited by meepmeepmayer
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5 minutes ago, meepmeepmayer said:

This better be true only for the older models!!!!!:furious:

@Marty Backe Since you only use the 3rd alarm on your Gotways, can you tell if they always occur at the same speed, or not and thus are in some way power/torque/battery-related?

I am pretty sure his answer is that he never hears them :-)

I have said that i asked that for my wheel...and i personal can only confirm that for my V3....but AFAIK this is for all GW models, that they call it the "80% alarm"....but that it is just coded at about 80% speed of each wheel. But hey...who cares ;-)

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And I thought I was safe from unexpectedly overpowering the wheel due to the 3rd alarm (if this is really true, but somehow I believe it):cry2:

How does KS do this, do they have a real overpower warning?

Crazy how the manufacturers don't even give such simple info. Who do we have to ask to get a definitive answer for Gotway wheels?

Edited by meepmeepmayer
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