KaleOsaurusRex Posted June 21, 2015 Posted June 21, 2015 It happened to my lady Justine today, with the generic tg t3 style, and then a week or so ago it happened to me on the Airwheel X8.She was just getting on the unicycle, and she says it suddenly acted as though it had been turned off, faceplanting her! It did the normal beep. The battery was more than half charged.When it happened to me, I was riding normally at around 5 miles per hour and it just stopped balancing. The wheel went tumbling end over end like a coin in a wide parabola curve kind of shape. I'm so lucky I was in exactly the right place, because it was in a public area and it really could have hurt someone.Anyone else experience anything like this? Any solutions? I hope it was user error.
esaj Posted June 21, 2015 Posted June 21, 2015 Did the wheel turn back on without having to plug the charger in? If it doesn't turn back on until the charger is plugged in, it's the infamous BMS overdischarge protection kicking in, there are instructions with pictures at least somewhere in the mod-section and vee73's "I plan to test"-thread about shunting them in different models. Although I'm not sure if it still does turn on without the charger with some brands/models, even after first cutting power? @Planetpapi also had a weird (maybe wheel malfunction) crash some time ago with a TG-F3: http://forum.electricunicycle.org/topic/338-my-first-butt-fall-im-officially-a-pro-now/
KaleOsaurusRex Posted June 21, 2015 Author Posted June 21, 2015 Thanks for the link esa! Both wheels functioned normally afterwards. There must be a safer way to manage overdischarge; I'm sure it's been discussed before but I wonder if the manufacturers know how important it is.
esaj Posted June 21, 2015 Posted June 21, 2015 My guess is that the at least the cheaper wheel manufacturers just use "off-the-shelf" BMS -circuit boards on the wheels, that aren't designed for this kind of use (lots of powerful discharges here and there due to accelerations and hill climbing), and the circuit boards are designed to save the battery from over discharge. Gotways don't have the over discharge protection circuitry in the boards, apparently Ninebots don't either, don't know about other "bigger manufacturers", but most generics and the Firewheel have it, and it must be shunted for the wheel to be really safe.It's not clear whether it was the overdischarge protection in Planetpapi's case, or something else, as (at least usually) the wheel will turn off and won't turn on after the protection has activated, until the charger is plugged in, but don't know if it is always the case.
hobby16 Posted June 21, 2015 Posted June 21, 2015 Thanks for the link esa! Both wheels functioned normally afterwards. There must be a safer way to manage overdischarge; I'm sure it's been discussed before but I wonder if the manufacturers know how important it is. The TG's BMS is notorious for its cutoff, especially when it's cold. Shunting its BMS is the solution, from my own experience and from several users who have taken the step and seen the improvment. I suggest everybody to shunt it, otherwise your wheel is outhright dangerous.New Gotways are now all with a safe BMS, ie where the cutoff circuit has been removed alltogether from the BMS. I have just checked it on my GW14" and others on their GW18".So I would say there are manufacturers (Solowheel, Ninebot, iMotion) who know the cutoff circuit should never be in the BMS, there is one manufacturer AFAIK (Gotway) who is aware of the problem and has rapidly taken steps to remove it (without saying it out loud so each user must verify it himself !), and lot of bloody #@&é~ manufacturers (Airwheel, TG, SML, Firewheel) who continue to integrate off-the-shelf for-bicycles BMS which are totally unsafe for monowheels.When cold weather will come next fall & winter this year, there will be a big wave of accidents due to the cutoff because a whole generation of ill-designed wheels has been sold and the manufacturers are too irresponsible and stupid to solve the problem quickly. The most notorious of them being Airwheel, I hope it will pay for its blunder dearly.
KaleOsaurusRex Posted June 21, 2015 Author Posted June 21, 2015 Wow, thanks for the responses. I didn't realize so many brands would require the shunt for safety. I hope this doesn't cause some accident that demonizes this technology in the public image. Segway had that thing where one of the founders drowned or whatever
esaj Posted June 21, 2015 Posted June 21, 2015 Wow, thanks for the responses. I didn't realize so many brands would require the shunt for safety. I hope this doesn't cause some accident that demonizes this technology in the public image. Segway had that thing where one of the founders drowned or whateverI think it was the new owner of Segway, who ran off a cliff with one of them after buying the company... And I shouldn't laugh, but still, the irony... I know I've ranted about the BMS-problem a lot here, and never had the problem myself (didn't ever occur with the generic, although I've never checked if it has the overdischarge protection, probably does, and the Firewheel is already shunted), but the idea that the wheel can shutoff basically ANY TIME, but especially with low battery/cold weather, is so dangerous that I think voiding the warranty on batteries is a small price to pay for safety and everyone should do it on wheels that have it. Very few people are balanced enough to stay up if the wheel stops balancing you back and forth (I'm not, but maybe someone who has ridden normal unicycles a long while could do it for a while, but probably not even them if it happens really suddenly), and especially at high speed this can cause some serious injuries, even fatalities without enough protection.
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