Shkani04 Posted April 29, 2016 Share Posted April 29, 2016 Hi, so after my fall today I found and joined this forum to see gather your opinions as to why my ninebot was dysfunctional I was riding on my ninebot for about 30 min or so hitting max speed several times. But the last instance after I hit max speed, it beeped but then quickly gave out and I had a pretty nasty fall. Usually when a person hits max speed on the ninebot, the machine pushes back on the balls of their feet and makes them slow down.This time it did not do that. I am not new to the ninebot and have been riding for about 6 months without a crash. I thought I dislocated my shoulder but thankfully everything was ok except for cuts all over. I just do not know why this happened. Now I am hesitant to ride it again and to hit max speed. Any reason why this could have happened? any remedy or fix for this problem? Thanks for you time and help, I look fwd to your replies! H. Link to comment Share on other sites More sharing options...
Cloud Posted April 29, 2016 Share Posted April 29, 2016 Hard to say what exactly happened, but maybe you simply overleaned? Were you on an incline?On a battery close to empty, and at high speed, too much leaning can make the euc give out. Link to comment Share on other sites More sharing options...
Shkani04 Posted April 29, 2016 Author Share Posted April 29, 2016 hm thanks for the reply., I wasn't on an incline and i had 68% of my battery left. I didn't feel as if i leaned more than usual either. Link to comment Share on other sites More sharing options...
US69 Posted April 29, 2016 Share Posted April 29, 2016 How old Is your Ninebot? E plus? Perhaps The Batterie Is getting weak? Flat tire so The Motor has to work harder... Link to comment Share on other sites More sharing options...
SlowMo Posted April 29, 2016 Share Posted April 29, 2016 My advice is just ride moderately and everything will be ok. Always pushing the machine to it's limits is not advisable. You might have over accelerated and the motor could not keep up. Also try to see the alignment of your Ninebot. There is a manual calibration tutorial created by @SuperSport at the link provided below: Link to comment Share on other sites More sharing options...
jer Posted April 29, 2016 Share Posted April 29, 2016 I think you had a BMS shut down. I changed my battery to one from 1radwerkstatt which has been completely faultless and has more capacity, almost 390 mah. I run this down to 30% and it does not show random shutdown behaviour. I think the standard battery has issues, with the BMS shutdown and maybe cell quality Having said that I only ran into issues at 50% and less, with the thing conking out with no warning like there was no tomorrow. So not sure why you would shut down at 70% power though. Maybe you were riding quite hard and the voltage under load had dropped to a point where the BMS kicked in. After sitting round for a few minutes the voltage and hence fuel level can go up. Riding round for 30 minutes or so, might have depleted the battery sufficiently for a BMS shutdown. Of course you need to get on it again to see if it wasn't something else. BMS shutdown are not nice, thats for sure. I hope your bruises... etc get better soon Jer Link to comment Share on other sites More sharing options...
Chriull Posted April 29, 2016 Share Posted April 29, 2016 Here were already some incidents like yours reported - unfortionately no real 100% cause was found (imho)... As far as i remember, your incident is the only one, that got the "beeps" as warning before. So the ninebot still had a last chance to tell you, that something goes wrong - but as it seems not early enough... The beeps from the ninebot come imho in overpower, undervoltage or overtemperature situations - overtemperature can imho in your case be ruled out. Ninebot is not really known to be very overtemperature prone - this normaly only happens with some combination of higher rider weight and/or steeper/longer inclines and/or "high" ambient temperatures. And then normaly the ninebot throws in quite a "hefty" tiltback, if the warning is ignored... Overpower should also not really happen by riding "normally" on a straight road with 70% battery, no bumps and no hard accerleration - but who knows... So it's maybe the undervoltage warning - The ninebot "noticed" a too strong voltage drop (maybe internally combined with some kind of overpower detection - so that the ninebot "sees" voltage down, and for this too much power requested?). Normally (imho) in this state the ninebot would/?should? throw in a tilt-back to reduce your speed to 10 km/h (first reduction of max speed in case of low battery/overtemperature). This quite strong tilt-back in this already "weakend state" of the battery could have caused a single cell voltage to drop even further and go under the BMS threshold, so the BMS cut out (because of single cell undervoltage somewhere between ~2,7-3V). This BMS cutout is not easy to identify for sure, because the battery pack gets fully functianal again after the cell recovered the voltage over the threshold - which imho happens in the time one recoveres from the crash. If the Ninebot was turned off and you could turn him on again (maybe after a short pause?), this could be a clue, that this happened... To be sure about this, you would have to open your battery pack (remove the blue/yellow plastic "wrap" cover) and measure all the individual cell voltages (!Attention: LiIon cells are very powerfull and nasty things can and will easily happen if the are short-circuited). If with about 70% charge one cell (pair) gets below the BMS undervoltage threshold then this cell pair is definitely "bad" and should be imho easily identified by measuring the voltages. But of course you void your warranty by doing this...But imho battery pack warranty is limited to 6 months - so it would be over anyhow? The other BMS cut-off reason can be ruled out? The overcurrent cut-out - if this would have happend you had to reset the BMS to be able to turn the ninebot on again by connecting it to the charger or dis- and then reconnecting the battery. Another reason that came in my mind for these kind of incident is, that the ninebot strangely from time to time tilts slighty forward for a couple of seconds and then drives straight again, as if nothing happened. If this occurs to one near max speed and gets one out of balance, so one already "falls" forward (accelerating the ninebot even further) this could lead to an overlean, where the ninebot does not have enough power reserves to stabilize or give the max speed tilt back. Generally the ninebot has about enough power for driving the 20 km/h with the 500W motor and the 340Wh battery pack - but the torque reserve gets less and less the faster you drive. So overleans can happen easier at higher speeds with maybe some small inclines/bumps, and "weak" battery situations and a not to carefull acceleration... Here a forum member made a nice logging app for iPhone It won't help you analyzing what happened with this accident, but could provide you information with your future rides if something is not really as it should be... Unfortionaltely the ninebot sends the voltage values slower/"irregularely" so that one important value cannot be shown in full detail ;( So the best (but absolutely unproven) guess would be imho the battery. Best remedy for this would be a new battery pack from an experienced (in regard to EUC batteries) and reputably battery pack manufacturer. As the ninebot packs are not bad (they use high quality cells) and have a quite nice BMS, the miss one point - they only use the internal balancer of the chips on the BMS which leads/could lead to premature cell aging... But a new pack is quite an investment compared to the ninebot price itself - especially as long as it's not secure that this was the real reason... ;( ps.: the original post exists two times (http://forum.electricunicycle.org/topic/3867-dysfunctional-ninebot-crash-thoughts/?do=findComment&comment=40333) - maybe it should be put together? Link to comment Share on other sites More sharing options...
Shkani04 Posted April 29, 2016 Author Share Posted April 29, 2016 Sorry for the double post. The moderator Can delete the other post. But wow, Thanks so much for the responses. You guys are great. In the past I have been very aggressive with acceleration but the machine always corrects me. I do not feel like this occurrence was a special circumstance from any other time that i aggressively accelerated. firmware V1.3.5 - latest one. Model E+. I haven't even used this ninebot THAT much. total cycling mileage is 34.2 So i don't think the battery should be getting weak just yet. I will try using that app but that means i have to get back on it to see what may be potentially wrong. I will also try and manually re-calibrate the machine. which battery do you suggest I replace the current with one with? link? Thanks again for all of the feedback! Haris Link to comment Share on other sites More sharing options...
SlowMo Posted April 29, 2016 Share Posted April 29, 2016 1 hour ago, Shkani04 said: which battery do you suggest I replace the current with one with? link? There is no need for you to spend money on another battery. Just handle your Ninebot with TLC and you will be OK. Link to comment Share on other sites More sharing options...
Shkani04 Posted April 29, 2016 Author Share Posted April 29, 2016 haha will do. I will keep you all posted on my next ride next week. Link to comment Share on other sites More sharing options...
MetricUSA Posted April 29, 2016 Share Posted April 29, 2016 So there are maybe three 'conditions' that can cause a problem, but sadly in the end, unless recorded, there is no way for knowing for sure what happened, a need for a 'black box' or log is needed to diagnose... Link to comment Share on other sites More sharing options...
Chuts Posted May 1, 2016 Share Posted May 1, 2016 Over leaning is usually the culprit. Most cases you could be riding under the threshold of the engine cutting when you meet a bump/hole or small incline in your path which tips the scales for a split second, enough for our engine to shutdown. Link to comment Share on other sites More sharing options...
jer Posted May 1, 2016 Share Posted May 1, 2016 The other possibility is that you have left the battery fully charged and it's internal resistance has increased. Resulting in voltage drop under load. If you are in Europe you have the below to get batteries https://www.facebook.com/1radwerkstatt/photos_stream To look after the battery one of these http://hobby16.neowp.fr/2016/02/06/charge-doctor-v2-10a-3/ I only charge to full capacity 100 % just prior to use . The ninebot is a good wheel, tough, compact etc, but let down by it's original battery/ BMS in my view. The mainboard management has worked fine for me with a decent battery. I can now ride with the battery down to lower levels and don't get strange behaviours. Jer Link to comment Share on other sites More sharing options...
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