Is King Song the safest / best electric unicycle available? References collected here.

[KaleOsaurusRex]

Hey guys! I'm trying to collect all of the documentation about why King Song may be making the safest wheel out there right now. If anyone feels like posting references or arguments for/against to help out, please put them here so we can get all of this info in one place. The goal is to have people riding as safely as possible.

1. Avoiding BMS shutdown

a. King Song's battery management system does not regulate power to the control board. Lacks the "power cut mosfet."

http://hobby16.neowp.fr/2015/07/24/gotway-bms-shunt/

http://hobby16.neowp.fr/2015/07/29/king-song-gotway-comparison/
(these two links referenced, as King Song control board is based on newer Gotway control board)

b. Higher capacity versions (64 cell versions -- 520wh and 680wh) of King Song unicycles avoid the problem altogether by making it very difficult to reach a low battery level that would be unsafe.

c. Low-battery tiltback - Locks (reference needed), forcing user to charge before riding again (ideal safe low-battery behavior) At low voltage, beeps at 50v, tilt back at 48v - information from direct email with King Song

 

2. Avoiding Main Board Shutdown

a. High-speed tiltback

b. Tiltback when thermal/electrical limits are reached (reference needed)

c. High-voltage tiltback stops user from riding downhill when battery is too fully charged. (at high voltage, beeps and tilts back at 69v) - information from direct communication with King Song

 

Other features:

a. Waterproofing/sealing:
http://forum.electricunicycle.org/topic/892-king-song-weather-rating-and-replacement-parts-availability/?do=findComment&comment=9139

http://hobby16.neowp.fr/2015/07/29/king-song-gotway-comparison/

b. Open-bottom design to avoid catching gravel (see pictures on unit) (reference needed of the firewheel/ninebot that just got torn up when gravel got inside)

c. Durability of outer shell:

d. Thorough testing of components:

e. Ability to ride uphill / push the unicycle, without reaching safety limits:

f. Large aluminum heatsink positioned strategically keeps the temperature low inside the unit

http://hobby16.neowp.fr/2015/07/29/king-song-gotway-comparison/

[KaleOsaurusRex]

@Jason McNeil @hobby16 @esaj

I want to get people in on this discussion to put the references here, so inviting some great minds. Perhaps you guys know who else to bring in to the discussion?

Some things I want to put in this post:

a. I read somewhere on these forums that the King Song unis lock on low battery, requiring charging before riding again. This seems like ideal low battery behavior to avoid unsafe low-battery riding.

b. Also, trying to find a reference for the type of tiltback that would happen if you rode at top speed or uphill for a very long time. I think the unit tilts back and won't let you ride until it cools down, or something like that?

c. There's a picture somewhere showing what happens when gravel gets into the round closed style unit on high speeds; pretty sure I saw one that basically exploded.

Are there any other reasons for unexpected shutdown I've missed? Probably

[Jason McNeil]

@KaleOsaurusRex

b. Also, trying to find a reference for the type of tiltback that would happen if you rode at top speed or uphill for a very long time. I think the unit tilts back and won't let you ride until it cools down, or something like that?

That's not quite right, it's related to the battery cells voltage sag: the cells that are used by the KS series drop off more quickly than some other types. Lowering the voltage threshold helps this condition. The way the control-board is programmed this is NOT a safety issue, since the tilt-back is programmed to be progressive & predictable. It was written about quite extensively here:   
http://forum.electricunicycle.org/topic/1055-usable-wh-in-ks-680wh-only-~500wh/#comment-10383

[Belly laughing]

A belated regret though, I would yet think what if I have read this posts before buying Gotway MCM4 HS on 09May2016...

I had heard Gotway MCM4 HS was awesome from watching a video on YouTube but I didn't know King Song is such a good brand 

 

 

[Mono]

8 hours ago, Belly laughing said:

A belated regret though, I would yet think what if I have read this posts before buying Gotway MCM4 HS on 09May2016...

I guess you (don't) know that the OP is selling KingSong wheels?

[Belly laughing]

Yeah.  I didn't know the time I purchased Gotway MCM4.

Before that day (09May2016), I didn't try any electric unicycle before: I was a noob.

[Casey]

I just got back from the ER.  I accelerated quickly and I am pretty sure I had a kickback.  Eleven stitches, not a big deal.  Still, something to watch out for.  I am used to beeps so I think I accidentally accelerated through the beeps into a kickback.  Went from max speed to zero really quick.  I know that I didn't hit any thing and my wife was behind me and said it looked like I was tossed into the air.

[Cloud]

1 hour ago, Casey said:

I just got back from the ER.  I accelerated quickly and I am pretty sure I had a kickback.  Eleven stitches, not a big deal.  Still, something to watch out for.  I am used to beeps so I think I accidentally accelerated through the beeps into a kickback.  Went from max speed to zero really quick.  I know that I didn't hit any thing and my wife was behind me and said it looked like I was tossed into the air.

What were you riding?!what threw you off, the rapid tiltback or the wheel shutting down?

[UKJ]

I like Cloud would very much like to know more about your accident please.

May I ask what safety gear you were or were not wearing and battery level?

I will add that now having about 400 miles on my Ks 14c that have never had any issues other than over heat when doing freestyle, I trust my EUC more and more, but always have at the bare minimum quality wrist guards and helmet, and if trying new things or off road a full battery of protection!

I have it unlocked and push to 28 ks almost every outing and find myself cruising at about 25 easy and under full control.

ukj

[Casey]

I was on my KS14(c). I had been riding it back and forth to work most of the days of this week.  Great peppy machine.  It was pretty warm this morning and my wife and I were going to the farmers market and another event in town.  About a half mile from home I swerved around a skunk and kept cruising.  I have no way of knowing my top speed but I wasn't going that fast.  Also, I think my stop speed is either 30 or 32 Khalid, with beeps a couple below and I was not beeping.  I have app connectivity issues so I am not sure of my settings.

So I was cruising and decided to punch it for a bit of thrill.  I heard a single and a double beep in rapid succession and I was still leaning into it a bit.  Then, I remember something like being bucked.  My wife said it look like I went back, then flew forward.  When I gathered up myself, found my sunglasses in the nearby ditch, and calmed my wife I had to power on the machine to head back.  I was just wearing shorts and a short sleeve button up with converse sneakers, no protective gear.  I will not ride with protective stuff, because it would be too hot.  I would just drive my truck.  

I do not know for sure if the wheel shut down after I fell off or before.  I don't know if it shutoff or tilted back and bucked me off.  I ride the wheel about every day and I am pretty good on it.  However, I believe it was a tilt back caused by my sudden acceleration, maybe in conjunction with the hot morning.  The road was flat and I was in control until the wheel kicked or quit.  It really reminded me of a kickback with a chainsaw.

Has Kingsing had any issues with shutdown or unexpected tilt back?  Still love my wheel.  Thanks.

[Cloud]

4 hours ago, Casey said:

I was on my KS14(c). I had been riding it back and forth to work most of the days of this week.  Great peppy machine.  It was pretty warm this morning and my wife and I were going to the farmers market and another event in town.  About a half mile from home I swerved around a skunk and kept cruising.  I have no way of knowing my top speed but I wasn't going that fast.  Also, I think my stop speed is either 30 or 32 Khalid, with beeps a couple below and I was not beeping.  I have app connectivity issues so I am not sure of my settings.

So I was cruising and decided to punch it for a bit of thrill.  I heard a single and a double beep in rapid succession and I was still leaning into it a bit.  Then, I remember something like being bucked.  My wife said it look like I went back, then flew forward.  When I gathered up myself, found my sunglasses in the nearby ditch, and calmed my wife I had to power on the machine to head back.  I was just wearing shorts and a short sleeve button up with converse sneakers, no protective gear.  I will not ride with protective stuff, because it would be too hot.  I would just drive my truck.  

I do not know for sure if the wheel shut down after I fell off or before.  I don't know if it shutoff or tilted back and bucked me off.  I ride the wheel about every day and I am pretty good on it.  However, I believe it was a tilt back caused by my sudden acceleration, maybe in conjunction with the hot morning.  The road was flat and I was in control until the wheel kicked or quit.  It really reminded me of a kickback with a chainsaw.

Has Kingsing had any issues with shutdown or unexpected tilt back?  Still love my wheel.  Thanks.

Ive ridden about 4000 km or so on my kingsongs 14c and  believe ive experienced anything and everything that can happen on a kingsong 14" wheel. Ive faceplanted, ive had shutdowns for many different reasons, some were my own fault or negligence or complacency, i had issues/ malfunctions, many attributable to my weight (100kg). I now know what can or cannot happen and I still consider them reliable in many ways. I still love my wheels and i can do cool things on them, i feel like they are an extension of my feet now..

It is natural to not remember if the wheel shut down before the fall or was still on. Its actually quite interesting because i faceplanted quite a few times now and every time this happens, i get up pick up the wheel and continue riding but for the life of me i can never remember if i have to turn the wheel back on or its still on when i pick it up. During an accident something happens to the brain that it processes information in a different way and we are unable to remember these little details.

Its a pretty safe wheel but there is a few things that could have happened. You are saying you could have been going at 30- 32 km/ hr but you dont think so simply because there were no beeps? How is it that the wheel allows you to go this fast? Most wheels are capped at 30kph. When did you buy the wheel? Where are you located and who did you buy the wheel from? How much do you weigh? How rapidly did you accelerate? Whats the battery size in your kingsong and what was the battery level when this happened?

one thing it was not, is  tiltback. You may have had the tiltback but its not the reason you fell. Also, its not overheating. When kingsong overheats it gives you enough time to get off and the overheating tiltback is very gradual. Answer the questions below and then maybe we can figure out what happened.

[UKJ]

Thanks @Casey for the reply.

May I respectfully submit that not wearing ANY protective gear is not a good option, heat issues included.

I must agree with @Cloud that I do not think you had either tilt back and, or over heat causing your crash IMHO!

Maybe do what ever it takes to get your wheel connected then set beeps 28 29 30 and tilt back 30 also and accelerate slowly to get to high speed and know to be careful when hearing beeps.

You did not answer the battery level question, do you remember how many bars you had left?

ukj

 

[US69]

12 hours ago, Casey said:

I was on my KS14(c). I had been riding it back and forth to work most of the days of this week.  Great peppy machine.  It was pretty warm this morning and my wife and I were going to the farmers market and another event in town.  About a half mile from home I swerved around a skunk and kept cruising.  I have no way of knowing my top speed but I wasn't going that fast.  Also, I think my stop speed is either 30 or 32 Khalid, with beeps a couple below and I was not beeping.  I have app connectivity issues so I am not sure of my settings.

So I was cruising and decided to punch it for a bit of thrill.  I heard a single and a double beep in rapid succession and I was still leaning into it a bit.  Then, I remember something like being bucked.  My wife said it look like I went back, then flew forward.  When I gathered up myself, found my sunglasses in the nearby ditch, and calmed my wife I had to power on the machine to head back.  I was just wearing shorts and a short sleeve button up with converse sneakers, no protective gear.  I will not ride with protective stuff, because it would be too hot.  I would just drive my truck.  

I do not know for sure if the wheel shut down after I fell off or before.  I don't know if it shutoff or tilted back and bucked me off.  I ride the wheel about every day and I am pretty good on it.  However, I believe it was a tilt back caused by my sudden acceleration, maybe in conjunction with the hot morning.  The road was flat and I was in control until the wheel kicked or quit.  It really reminded me of a kickback with a chainsaw.

Has Kingsing had any issues with shutdown or unexpected tilt back?  Still love my wheel.  Thanks.

For me this Sounds like exactly what Happends to me....to fast accelaration After about 25kmh and than massive tiltback....Read experience and Diskussion Here:

 

as you "decided to punch the Thrill" ...which Seams to have been on a too fast riding.....i Would not blame The Wheel ;-)

[Casey]

Battery was 80% wheel was and is in great shape.  It is a KS14(c) 800w, 600+WH unit.  When I said I accelerated through the beeps, I meant that I was accelerating very fast, such that I heard a single and a double beep, but I didn't lean back quick enough after the double beep.  After the double beeps I was airborne.  Totally my fault.  I think it was a rapid tilt back instead of a shutdown for four reasons.  First, if my memory is right, it felt like getting bucked.  Second, the distance and trajectory of my flight was up and forward, not just a forward and down like a face plant.  Third, I didn't get a mark on my face, which is pretty much the opposite of the expected result of a shut down and killing of the gyro.  Finally, my wife saw the whole thing from behind me.  She said she thought I came backwards, then flew up and forward.

i am not complaining about the wheel.  I am not claiming that is unsafe.  Eleven stitches is not a bad crash for all of the fun I have had on my wheel.  I really like my wheel, except that the batch of wheels that shipped with mine all have app connectivity issues.  It is annoying in a car stereo not working sort of way, not in a ford pinto safety or Saab endless repair bill way.  It's a great wheel and I ride it beeping on this one straight stretch all the time.  I would just advise against exceeding that second set of beeps.  Oh, and I bought my wheel from a reputable dealer that has provided great service and guidance on dealing with app issue.

[US69]

Really....EXACTLY....like my Crash on The Ks16....

agessive tiltback because of to agressive accelaration...i only Had Last Warning on 29....and as i accelarated WAY to fast ...The tiltback was WAY to agressive....

now i learned my lesson and changed The Warning Settings....

[Casey]

I can't get into th app to change my settings until they send me a thing so I can flash my firmware so my settings are staying put.   I don't think it is a warning issue as much me goofing off too close to the wheel's outer limits.  It just sucks.  Extreme acceleration is so much fun on these wheels.  I hate that I have to be more careful.  Kingsong69, thanks for helping me realize I am not crazy.  I knew it felt like a chainsaw kickback.  And now, I know what behavior to correct.  Again, thanks.

[US69]

you are welcome!

as Jason mentioned The tiltback Should not kick in so hard and even on a to hard acceleration come in "mildly".....

even as the KS have a lot of Safety reserves until they run into a shut off....

[Cloud]

4 hours ago, Casey said:

Battery was 80% wheel was and is in great shape.  It is a KS14(c) 800w, 600+WH unit.  When I said I accelerated through the beeps, I meant that I was accelerating very fast, such that I heard a single and a double beep, but I didn't lean back quick enough after the double beep.  After the double beeps I was airborne.  Totally my fault.  I think it was a rapid tilt back instead of a shutdown for four reasons.  First, if my memory is right, it felt like getting bucked.  Second, the distance and trajectory of my flight was up and forward, not just a forward and down like a face plant.  Third, I didn't get a mark on my face, which is pretty much the opposite of the expected result of a shut down and killing of the gyro.  Finally, my wife saw the whole thing from behind me.  She said she thought I came backwards, then flew up and forward.

i am not complaining about the wheel.  I am not claiming that is unsafe.  Eleven stitches is not a bad crash for all of the fun I have had on my wheel.  I really like my wheel, except that the batch of wheels that shipped with mine all have app connectivity issues.  It is annoying in a car stereo not working sort of way, not in a ford pinto safety or Saab endless repair bill way.  It's a great wheel and I ride it beeping on this one straight stretch all the time.  I would just advise against exceeding that second set of beeps.  Oh, and I bought my wheel from a reputable dealer that has provided great service and guidance on dealing with app issue.

Well, first of all the first level of speed beeps is 2 beeps, not 1. Also, i dont understand how an aggressive tiltback can throw you up in the air? There isnt any forces that are pushing your whole body up. I am not saying you didnt have the tiktback, you probably had it, and if you accelerated thru a big range of kph very fast, and you were already at the limit, then the tiktback woukd come in fast, but it can really throw you up in the air in my opinion. Maybe you got scared and jumped up?  yes the severe tiltback can cause you to lose balance and fall off the wheel, but i just thought that if it was just the tiktback, you would be able to remember why you fell. Since you didnt know exactly what happened, i thought you ether had a shut down or an overlean/ overspeed kind of situation when the wheel could no longer cope with the load and hold you upright. I am still wondering how the wheel allows you to set the speed higher than 30. Perhaps you bought it around october, november last year when kingsong had a batch of wheels going to 35 kph which also had connectivity issues. Tell me if i am right.

[edwin_rm]

I've been ejected by the tilt-back on my Solowheel Xtreme mutltiple times. With SW the tilt-back gives a MASSIVE pedal lean (way stronger than KS), near impossible to stand on the pedals after a certain speed. Accelerating too quickly on SW leads to the tilt-back to act as an ejector, rather than gradually rise (in other words, it launches you into the air). The wheel does not lose power at all. In other words, yes, it's possible that what he experienced was an over-acceleration ejector tilt-back. This is very different from a power cut-off. With the power cut-off, the wheels would first sink forward, before actual shut off. With power cut off there is not the violent eject, the wheel simply drops you to the ground.

Source: I've experienced both kinds of accidents (tilt-back eject on Solowheel, and power cut-off on Gotway).

[Cloud]

1 hour ago, edwin_rm said:

I've been ejected by the tilt-back on my Solowheel Xtreme mutltiple times. With SW the tilt-back gives a MASSIVE pedal lean (way stronger than KS), near impossible to stand on the pedals after a certain speed. Accelerating too quickly on SW leads to the tilt-back to act as an ejector, rather than gradually rise (in other words, it launches you into the air). The wheel does not lose power at all. In other words, yes, it's possible that what he experienced was an over-acceleration ejector tilt-back. This is very different from a power cut-off. With the power cut-off, the wheels would first sink forward, before actual shut off. With power cut off there is not the violent eject, the wheel simply drops you to the ground.

Source: I've experienced both kinds of accidents (tilt-back eject on Solowheel, and power cut-off on Gotway).

Ive experienced massive tiltback also as well as power cut offs, overleaning etc. it could be both, i think he had the tiltback and possible then the wheel dove and / or cut off. I just didnt think the tiltback can actually visibly throw you up in the air. Maybe i am just too heavy to be thrown up in the air lol. Whatever this was, one should never accelerate too fast e pecially at high speeds

[Rehab1]

Wow...the thought of falling off backward is worse than a face plant. I take it you survived. I've seen so many closed head injuries in my practice that that thought of hitting my head backwards scares me.  Tilt back has happened to me a few times but yesterday's tilt really caught my attention. Since there is no warning I am now just concentrating on the motor/wheel sound to zone in on when a tilt back may be approaching.

[Casey]

Cloud, i don't know how fast I was going, but it was fast.  I don't know because my wheel is from that batch you speak of.  I am trying to get connectivity again, but the only time I was able to talk to my wheel I think I set the speed at 28, 29 and 30. Fantastic machine.  

Rehab1, I didn't fall backwards, the tilt back caused a buck.  I still went forward but it was after being popped back and up a bit, according to my wife. My Mellon is fine.  

Edwin, ejector is spot on.  Great description.  Sorry that you have experienced the same type of flight.  

[US69]

1 hour ago, Rehab1 said:

Wow...the thought of falling off backward is worse than a face plant. I take it you survived. I've seen so many closed head injuries in my practice that that thought of hitting my head backwards scares me.  Tilt back has happened to me a few times but yesterday's tilt really caught my attention. Since there is no warning I am now just concentrating on the motor/wheel sound to zone in on when a tilt back may be approaching.

read the link, where we spoke about my crash in detail...sure the tiltback dont push me "up".... but it was so massive snd agressive i couldnt stand any more....

i have experienced lot of normal tiltbacks...no prob...they just give you a little sign of beeing to fast....

 

but if you cross the tiltback setting of 30kmh so very fast by overaccelerating from -lets say 27 to 35- by massive lean forward...the way more agressive it kicks in...andgives you a wobble back and forth that you are not able to react on it correctly...

 

easy way to test: set tiltback to 10 kmh and give full power acceleration......and see what it did to you ;-)

[Jason McNeil]

I don't think there's any easy engineering solution to hard acceleration & hitting the max speed wall: if your 10kph-30kph acceleration is say 2 seconds, by the time you attain the 30kph max speed, tilt-back is going to feel very violent. Without tilt-back, you may or may not face a cut-out. Implementation choices among responsible Wheel makers is choosing the 'LEAST BAD' option. 

Hard acceleration is a classic overshoot situation, system needs to correct, but how?!

[US69]

4 minutes ago, Jason McNeil said:

I don't think there's any easy engineering solution to hard acceleration & hitting the max speed wall: if your 10kph-30kph acceleration is say 2 seconds, by the time you attain the 30kph max speed, tilt-back is going to feel very violent. Without tilt-back, you may or may not face a cut-out. Implementation choices among responsible Wheel makers is choosing the 'LEAST BAD' option. 

Hard acceleration is a classic overshoot situation, system needs to correct, but how?!

you are right!

hard to choose the correct way....do it to fast....tiltback is too agessive...

do it to slow....you run in a "cut off"...

KS is tryimg to do its best....i think ;-)

 

like i said: i do not blame the wheel! was my stupid over accelaration....thats it!!!

i learn the painful way :-)..... will nver happen again !