mark321 Posted December 6, 2015 Share Posted December 6, 2015 I had my first serious crash just now. It was 11.5 miles into a ride and on a slight uphill on a very smooth road. According to my phone that was recording the ride, I was going somewhere between 13.5 and 14.8 mph and the grade was 1.5%. I was accelerating and suddenly the cycle just didn't have enough power to stay under me and I toppled forward. When I looked at the battery meter afterward it showed 4 bars. I'm pretty sure on a full charge it would have easily stayed under me at that speed. This was on a kingsong 14" 800W 680Wh. As far as overall speeds traveled, according to my ride metrics it was a 62.8 minute ride and I had spent 19.5 minutes at 0-9 mph 15.0 minutes at 10-12 mph 17.0 minutes at 13-15 mph 9.5 minutes at 16-18 mph 1.8 minutes at 19-21 mph After the crash I limped home the last mile or so at 10-12mph. Total moving average: 12.6 mph (max 22.1 mph). I came away with only minor injuries for what it's worth. I had harbinger fingerless weight lifting gloves on and tried to go into the fall with my palms. It mostly worked except somehow I let my fingers curl under on my left hand instead of keeping them straight, so I tore up the knuckles on that hand. I didn't have any knee protection other than my pants, and my right knee hit pretty hard too and is moderately scratched up. But I do think the majority of the impact went into my palms and they were adequately protected. Link to comment Share on other sites More sharing options...
mark321 Posted December 6, 2015 Author Share Posted December 6, 2015 Oh, and for what it's worth I didn't start the ride on a full charge. I don't have data, but I'll guesstimate I had ridden 5+ miles already since the last charge. Link to comment Share on other sites More sharing options...
Compuatic Posted December 6, 2015 Share Posted December 6, 2015 What unicycle? Link to comment Share on other sites More sharing options...
SlowMo Posted December 6, 2015 Share Posted December 6, 2015 Sorry to hear about your fall. How far have you ridden the KS14C since you purchased it? 14.8 miles is normal cruising speed for this model and should have not caused a sudden shut down. Link to comment Share on other sites More sharing options...
houseofjob Posted December 6, 2015 Share Posted December 6, 2015 @mark321 if the uni was still powered on post crash, you were overleaning. if the uni was off, then the BMS shut the unit off to protect the battery/mobo from a potential fire/explosion. All EUCs have BMS shutdown points as protection (outside of shunting the unit). All EUCs cannot infinitely accelerate faster (overleaning) and at some point, will fail to do it's job keeping you upright while spinning the wheel. These will be compounded by lower battery capacity, weather extremes (winter cold, summer heat), and going uphill. Your max speed/acceleration at 10 bars will not necessarily always be your max speed/acceleration at 4 or 3 bars, especially if you weigh more, are going uphill, or are riding in colder/hotter weather. Link to comment Share on other sites More sharing options...
Cloud Posted December 6, 2015 Share Posted December 6, 2015 1 hour ago, mark321 said: I had my first serious crash just now. It was 11.5 miles into a ride and on a slight uphill on a very smooth road. According to my phone that was recording the ride, I was going somewhere between 13.5 and 14.8 mph and the grade was 1.5%. I was accelerating and suddenly the cycle just didn't have enough power to stay under me and I toppled forward. When I looked at the battery meter afterward it showed 4 bars. I'm pretty sure on a full charge it would have easily stayed under me at that speed. This was on a kingsong 14" 800W 680Wh. As far as overall speeds traveled, according to my ride metrics it was a 62.8 minute ride and I had spent 19.5 minutes at 0-9 mph 15.0 minutes at 10-12 mph 17.0 minutes at 13-15 mph 9.5 minutes at 16-18 mph 1.8 minutes at 19-21 mph After the crash I limped home the last mile or so at 10-12mph. Total moving average: 12.6 mph (max 22.1 mph). I came away with only minor injuries for what it's worth. I had harbinger fingerless weight lifting gloves on and tried to go into the fall with my palms. It mostly worked except somehow I let my fingers curl under on my left hand instead of keeping them straight, so I tore up the knuckles on that hand. I didn't have any knee protection other than my pants, and my right knee hit pretty hard too and is moderately scratched up. But I do think the majority of the impact went into my palms and they were adequately protected. So sorry to hear about the fall. it does sound like you were overleaning. Kingsong can stay upright down to the last drop of battery power but overleaning can happen even on the full battery Link to comment Share on other sites More sharing options...
mark321 Posted December 6, 2015 Author Share Posted December 6, 2015 I'd estimate my total riding distance since I got the wheel is maybe 35-40 miles. I agree the kingsong has been easily capable of well over 14.8 mph in general. I spend a lot of time in the 16 mph range and consider that a fairly comfortable cruising speed. The only reason I ever go slower than 15 mph is road conditions, which I have to be pretty careful of with a 14" wheel. Anyway I was still accelerating fairly hard at the time of the crash, and probably would have taken it up to 18 mph on that stretch of road. I doubt it was overheating either since it was no more than 50F outside, although I had been doing a fair amount of 18-19 mph riding shortly before the crash. My guess is still the battery, which could have managed that current fine if I was riding closer to a full charge. Link to comment Share on other sites More sharing options...
houseofjob Posted December 6, 2015 Share Posted December 6, 2015 bottom line, your KS-14 is not the same performer at sub 50% battery as it is closer to 100% it's the reason why I charge my KS-18 back up to 100% every chance I get. I don't enjoy riding a crippled EUC and don't understand the guys riding their uni's down to < 20%, plus you damage the lithium battery that way. Link to comment Share on other sites More sharing options...
mark321 Posted December 6, 2015 Author Share Posted December 6, 2015 Oh, I should also add that this was 50-60 meters after a stop sign. So I had been accelerating continuously from a stop up to that point. I bet if I had accelerated a little, then cruised a little, then accelerated some more etc the batteries would have been able to handle it. Link to comment Share on other sites More sharing options...
Cloud Posted December 6, 2015 Share Posted December 6, 2015 31 minutes ago, mark321 said: I'd estimate my total riding distance since I got the wheel is maybe 35-40 miles. I agree the kingsong has been easily capable of well over 14.8 mph in general. I spend a lot of time in the 16 mph range and consider that a fairly comfortable cruising speed. The only reason I ever go slower than 15 mph is road conditions, which I have to be pretty careful of with a 14" wheel. Anyway I was still accelerating fairly hard at the time of the crash, and probably would have taken it up to 18 mph on that stretch of road. I doubt it was overheating either since it was no more than 50F outside, although I had been doing a fair amount of 18-19 mph riding shortly before the crash. My guess is still the battery, which could have managed that current fine if I was riding closer to a full charge. It was not overheating. On iverheating kingsong doesnt fail performance. It just starts tilting back and force and allows you to continue riding if you can stay on the tikted pedals. 22 minutes ago, houseofjob said: bottom line, your KS-14 is not the same performer at sub 50% battery as it is closer to 100% it's the reason why I charge my KS-18 back up to 100% every chance I get. I don't enjoy riding a crippled EUC and don't understand the guys riding their uni's down to < 20%, plus you damage the lithium battery that way. Yes i am one of the people guilty or running the battery all the way doen to the last drop. It starts going slow, battery indicator flashing, then starts going on constant tiltback. Never fully gave out though. It must have been overlean 17 minutes ago, mark321 said: Oh, I should also add that this was 50-60 meters after a stop sign. So I had been accelerating continuously from a stop up to that point. I bet if I had accelerated a little, then cruised a little, then accelerated some more etc the batteries would have been able to handle it. 4 bars can handle constant acceleration over 60 meters. Link to comment Share on other sites More sharing options...
houseofjob Posted December 6, 2015 Share Posted December 6, 2015 the hot weather / cold weather part is not directly about performance, it's about battery capacity. lithium batteries under either extremes of weather will not be able to draw their full current capacity, eg. in sub 40ºF or 80+ºF weather, my 40% may become 30% while operating outside, but coming back indoors, will go back up to the proper battery level. in this case at 50ºF though, this had no effect. Link to comment Share on other sites More sharing options...
mark321 Posted December 6, 2015 Author Share Posted December 6, 2015 Yeah, I agree that it was overlean. For what it's worth the wheel was still on after the crash, so it wasn't any kind of BMS shutdown. I don't know if it was tilting the pedals back or not; it probably was. I think I've developed a bad habit of ignoring the angle the pedals are at. I started doing that in part because of the bizarre pedal-feel when turning in a circle (at slow speed). The pedals tilt downward as I'm turning and it feels like my toes should be scraping the ground by the time I turn all the way around. They're not of course, the "feel" is an exaggeration of reality, but it makes me not have much confidence in whatever the pedals are trying to tell me. Is the pedal tilt-back tuned so that it only happens when things are truly "serious"? The beeping is also too easy to ignore because it starts at a crazy-low speed, way way before there's any danger of overlean. Link to comment Share on other sites More sharing options...
Cloud Posted December 6, 2015 Share Posted December 6, 2015 9 minutes ago, mark321 said: Yeah, I agree that it was overlean. For what it's worth the wheel was still on after the crash, so it wasn't any kind of BMS shutdown. I don't know if it was tilting the pedals back or not; it probably was. I think I've developed a bad habit of ignoring the angle the pedals are at. I started doing that in part because of the bizarre pedal-feel when turning in a circle (at slow speed). The pedals tilt downward as I'm turning and it feels like my toes should be scraping the ground by the time I turn all the way around. They're not of course, the "feel" is an exaggeration of reality, but it makes me not have much confidence in whatever the pedals are trying to tell me. Is the pedal tilt-back tuned so that it only happens when things are truly "serious"? The beeping is also too easy to ignore because it starts at a crazy-low speed, way way before there's any danger of overlean. If this was overlean the pedals would have no time to tilt back. You woukd have overleaned before they would start to tilt back. Tilt back protection is not intended to warn you before overleaning. Definition of "truly serious" can be loose, but tikt back hapoens either when you are going too fast beyond a certain speed you set yourself,. Or when you are going beyond a factory set tiltback speed, or when you are drawing too much power for the battery left ( i,e, going uphill too fast especially on a lower battery), or upon overheating, or when battery is almost done on slower and slower speeds. In either case, kingsong allows you to continue at whatever speed you are going with the pedals tilted ( unless of course you exceed the ability of the wheel to hold you upright) Link to comment Share on other sites More sharing options...
houseofjob Posted December 6, 2015 Share Posted December 6, 2015 basically, (arbitrary numbers here) you cannot achieve 0 to 26 km/h in 3 seconds, but 0 to 26 km/h in 12 seconds might be fine. this can also be something like 26 km/h to 30km/h in 1 sec vs 26km/h to 30 km/h in 6 seconds. the combination of battery current, motor power and the gyro has it's limit of acceleration. Past that limit, the uni will simply cutout (not power off) because it cannot handle the load. it's the degree of acceleration, not about the continuousness of it, and yes, like @Cloud is saying, this is not a protection, ala BMS, but a limit of these 3 variables. Link to comment Share on other sites More sharing options...
mark321 Posted December 6, 2015 Author Share Posted December 6, 2015 There was some change in the sound of the motor right as the crash happened. I don't have enough experience to say whether the motor lost power and was starting to slow down or whether it was just maintaining a constant speed while I was trying to lean into it for more acceleration. Normally when I lean into it the motor gives a pleasant growl as it accelerates. The change in sound may have just been the lack of that growling sound if it was in tiltback and had decided to only give me a constant speed. I'm not sure on that. Link to comment Share on other sites More sharing options...
SlowMo Posted December 6, 2015 Share Posted December 6, 2015 If it is due to over leaning then this would be the the first time such occurrence happened which I doubt because the KS14C is well known for its motor endurance. Link to comment Share on other sites More sharing options...
Cloud Posted December 6, 2015 Share Posted December 6, 2015 1 minute ago, mark321 said: There was some change in the sound of the motor right as the crash happened. I don't have enough experience to say whether the motor lost power and was starting to slow down or whether it was just maintaining a constant speed while I was trying to lean into it for more acceleration. Normally when I lean into it the motor gives a pleasant growl as it accelerates. The change in sound may have just been the lack of that growling sound if it was in tiltback and had decided to only give me a constant speed. I'm not sure on that. I am just speculating here but is it possible that your perception of the last few seconds immediately before the crash has been affected by the shock of crashing? This happens to me a lot, when i try ti remember what happened right before some shocking event, my memories give me a twisted accound of what actually happened? I start remembering things that didnt happen or didnt happen the way i remember? Especially since you are saying the sound was different but not sure if it was a different sound or absence of the growling. I know if i crashed like that, i would probably start to remember all kinds of things happening right before. But then again the sound of the motor could have really changed. I know when i overlean nothing changes, i just fall forward, but maybe this is a different case. 3 minutes ago, SlowMo said: If it is due to over leaning then this would be the the first time such occurrence happened which I doubt because the KS14C is well known for its motor endurance. I dont know man, i overleaned several times on kingsong - its not so hard. Most of the time i was able to stay on, but a coupke of times had to jump off. Its easy to experience overlean when you are going over an uneven pavement and you dont notice it and dont adjust your lean. The wheel has to get out of the pothole and you continue leaning as if you are on smooth ground. You can lose balance easily Link to comment Share on other sites More sharing options...
SlowMo Posted December 6, 2015 Share Posted December 6, 2015 4 minutes ago, Cloud said: I dont know man, i overleaned several times on kingsong - its not so hard. Most of the time i was able to stay on, but a coupke of times had to jump off. Its easy to experience overlean when you are going over an uneven pavement and you dont notice it and dont adjust your lean. The wheel has to get out of the pothole and you continue leaning as if you are on smooth ground. You can lose balance easily Stalling when hitting potholes specially on grass always happen to me with my Gotway MCM2S which I just run away from. But motor suddenly shutting down on an even pavement is unique. I hope it doesn't happen again. Be safe. Link to comment Share on other sites More sharing options...
Cloud Posted December 6, 2015 Share Posted December 6, 2015 I dont think his motor shut down. It looks like the gyro couldnt keep him upright or the motor couldnt accelerate as much as he leaned Link to comment Share on other sites More sharing options...
houseofjob Posted December 6, 2015 Share Posted December 6, 2015 16 minutes ago, SlowMo said: If it is due to over leaning then this would be the the first time such occurrence happened which I doubt because the KS14C is well known for its motor endurance. Not true. I overleaned on my KS-18 800w 680wh. Quality of motor has nothing to do with it, overleaning exists for all EUCs due to the limits of current lithium battery tech. 20 minutes ago, mark321 said: There was some change in the sound of the motor right as the crash happened. I don't have enough experience to say whether the motor lost power and was starting to slow down or whether it was just maintaining a constant speed while I was trying to lean into it for more acceleration. Normally when I lean into it the motor gives a pleasant growl as it accelerates. The change in sound may have just been the lack of that growling sound if it was in tiltback and had decided to only give me a constant speed. I'm not sure on that. Dunno; I've had 2 overlean cutouts, 1 on a Ninebot One E+ and 1 on my current KS-18, and never experienced a particularly different motor noise. I will say that there is a hard to describe build up feeling at the peak of trying to accelerate faster before the wheel cuts-out and you head towards face-planting. Kinda like what I imagine a race car driver wrestling with high speeds before crashing or spinning into a crash. 5 minutes ago, SlowMo said: Stalling when hitting potholes specially on grass always happen to me with my Gotway MCM2S which I just run away from. But motor suddenly shutting down on an even pavement is unique. I hope it doesn't happen again. Be safe. The unit was still on after crash, this is not a BMS shutdown. Shutdown would mean no power to the uni post-crash. Link to comment Share on other sites More sharing options...
mark321 Posted December 6, 2015 Author Share Posted December 6, 2015 Yeah, there's always going to be a point where you're asking for more current than the batteries can give, and that point will vary with various factors including what charge-level I'm at. I'm positive that the level of acceleration I was asking it for is something it could have easily provided earlier in the ride. It was semi-aggressive acceleration though, so I guess it was just too much for the charge-level I was at at the time. Link to comment Share on other sites More sharing options...
Planetpapi Posted December 7, 2015 Share Posted December 7, 2015 Sorry about the fall. But you were wise enough to protect your self with protection gear. Got to appreciate it! Link to comment Share on other sites More sharing options...
checho Posted December 11, 2015 Share Posted December 11, 2015 Mark321, it sounds like an overlean situation having the batteries with more charge would have helped prevent this to some degree, however since we are taking about a 680wh battery pack, it is a very good size battery pack, so my conclusion is that you fell not because of speed but because of high acceleration and on a hill. One important data that we do not have is your weight. As your weight increases your acceleration decreases, or you take a risk of a faceplant. In other words a skinny lady that weights 40kg will be able to accelerate much faster than someone that weights 120kg. The weight of the driver and accelation are inversely proportional. For this reason heavy drivers should get unicycles with large battery packs and large motors. Also if going uphill it is the equivant of being heavier since the unicycle has to use much more power to move you compare to a flat surface, when going uphill it takes a lot less accelaration to overlean a unicycle. My recomendation on any hill accelerate very little, unless if you are really light and have a large battery pack and motor. Link to comment Share on other sites More sharing options...
mark321 Posted December 11, 2015 Author Share Posted December 11, 2015 I weigh 170# and I'm pretty sure I've previously accelerated more aggressively up steeper hills (when the charge was higher). In general the wheel has always felt like it has tons of power on reserve and has felt very confidence-inspiring. Right up until that overlean anyway. I haven't headed back out to the crash location to double check what would happen if I ride the same stretch the same way on a full charge, but I'm 95% sure it'll easily handle it. The fall hurt enough though that that tiny 5% doubt still has me a little gun shy. I don't think I can run it out or re-balance myself if I did get into an overlean again at that speed. Link to comment Share on other sites More sharing options...
checho Posted January 3, 2016 Share Posted January 3, 2016 On 12/11/2015 at 5:09 AM, mark321 said: I weigh 170# and I'm pretty sure I've previously accelerated more aggressively up steeper hills (when the charge was higher). In general the wheel has always felt like it has tons of power on reserve and has felt very confidence-inspiring. Right up until that overlean anyway. I haven't headed back out to the crash location to double check what would happen if I ride the same stretch the same way on a full charge, but I'm 95% sure it'll easily handle it. The fall hurt enough though that that tiny 5% doubt still has me a little gun shy. I don't think I can run it out or re-balance myself if I did get into an overlean again at that speed. In one of your posts you estimate your driving distance 35 - 40 miles, at 170# you probably had a very weak battery under load that could not deliver the needed power to the motor, when the battery meter read 4 bars it was not under load therefore getting a higher reading. Most likely the fall was an overlean with a weak battery, be safe do not run the battery that low. Link to comment Share on other sites More sharing options...
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