IPS T250+ accident

[Diego Novoa]

Hi there I just got an IPS T250+ from a friend that he rarely used, I’ve always wanted a unicycle, learned fast and quickly started to use it to go to the office, however I just had an accident and I could not find info or people that ran into the same problem.

I rode my IPS as usual to the office regularly  a 20min ride Around 5K, however today I was just entering to the office building and I was going full speed around 25Km/h on flat concrete when suddenly, the unicycle shut off the self balancing system out off nothing, shooting me off to the air and the straight to the floor with my arms and face to stop me, luckily there were no cars around me (and few people to watch the embarrassing moment) and just got one wrist injured and also left some of my arm’s skin on the concrete.

The battery level was more than 50%, and now the unicycle seems to be working just fine, but now I’m not sure if I want to ride it again knowing that this failure could happen again

Has anyone faced a similar situation?

[mrelwood]

Welcome to the forum, @Diego Novoa. Sorry to hear about your accident, hope you didn’t get hurt too badly.

If your IPS is anything like the T260 (couldn’t find info about T250) with a 260Wh battery, in my opinion 25km/h is not a speed it should be capable of achieving even when new. My first wheel was the IPS Lhotz with a 340Wh battery and possibly the same motor, and it also ditched me once when riding over a small drop during a downhill.

Your wheel is ancient, and the battery capacity and performance have probably weakened even further. Have you checked how the battery level drops when you ride? It doesn’t take much acceleration to make a tiny old battery to drop enough in voltage for the BMS of that era to cut the power, which is what I suspect might have happened. (Newer wheels don’t cut the power like that.)

In my opinion, for a wheel to be reasonably safe at those speeds it should have double the battery capacity (nearly fully charged of course) and almost double the motor power, like the Inmotion V8.

IPS used to announce the motor by it’s max power instead of the rated power, so their ”1000W” wheels were actually ~500W wheels.

Edited October 24, 2019 by mrelwood

[Mono]

On a less specific point, in general, electric motors deliver decreasing torque with increasing speed, while the torque demand increases with increasing speed. This means the electric unicycle is bound to run out of torque at some speed and the pedals will just dip forward. 25km/h is a very possible speed for this to happen in your case. Many modern wheels will limit the speed via tiltback such that this is much less likely to happen.