| Thank you for the detailed reply as well. I'm somewhat familiar with all of the problems and bugs with these particular OneWheel products and I agree that most of the actions taken by this particular company appear to be profit oriented as opposed to safety oriented. My original comment was not really aimed directly at defending them but rather just trying to start a discussion about something that I think comes up a lot and to provide what I regard as a slightly unpopular opinion. > Regarding BMS safety, the reason for removing control of the discharge path is that the device should always prioritize the safety of the user while riding. Instead of dropping the user to the pavement, pushback and audio alerts should be done to alert the user that one of the cells is having a voltage issue, or the pack is getting too hot. Bypassing the BMS's discharge does not effect charge protection, which is the main scenario of what would cause the battery to catch on fire and burn your house down. Yes, I agree with your assessment that this would be a reasonable order of priorities for a device like this. If you asked me to design a device like this, on the other hand, I would probably have built it with discharge protection, but have a "controller is driving the motor" pin for feedback where the BMS will give an X-second cutoff grace period. IMO, the discharge current should be set such that it doesn't trip at motor stall current, but does trip with a low impedance short at least (in such a failure scenario, the motor would have stopped anyway). Additionally, power to the ESC should definitely be removed when the device is safely powered off. I would personally be okay with it if they did what laptop manufacturers did and set a "permanent fail" flag in the BMS after being operated outside of its design parameters to prevent the battery from being charged again. The primary safety condition I'd like addressed is the case where a failure in the electronics while the device isn't being used may cause the pack or the electronics to start a fire (e.g. water ingress into device causing shorts, which has caused documented problems before; Apple actually applies potting compound to the BMS PCB in their batteries to supposedly address this case), though I am aware that charging appears to be where a lot of the hazards come from. > Unfortunately FM has been very strict on enforcing patents (even though they didn't technically invent the self balancing skateboard as there is prior art) and they have created a anti-competitive, anti-consumer market. To be honest, I think that this is the core of the problem. In a market where competitive products exist, defects are fixed rather quickly because customers can and will choose products without this unfortunate imbalance of power. If you look at the EUC market, there is plenty of innovation that leads to better products year over year - defects happen, but they appear to actually get fixed. > Regarding R2R there's people all around the world who ride these devices, and sending the board into their only location in Cali just isn't an appropriate solution. I think overall with this company, there's a good amount of kool-aid going around in the typical Silicon Valley fashion where people think they know everything about how the world and how customers work. If I remember correctly it's a business that started out of what was once someone's passion project and I'd imagine it is emotionally difficult for people to let go of their "children" and accept that the community and the customer base are ultimately going to take the product places they might not have imagined, and that the aftermarket and consumers are ultimately the deciders of where their vision will go. I feel like a lot of what they're doing could potentially just be a last ditch effort to maintain some semblance of ownership and control, but historically, the pioneer of a technology is not often the one that sees it through to maturity. |
Regarding discharge protection and BMS safety I completely agree with a hybrid approach of discharge protection with a grace period to alert the user if the device is armed. The main issue with battery safety is when the device is left unattended charging, but I do agree that ideally it should be shutoff completely while unattended. However, when riding, I would rather my board start smoking and catch on fire than ditch me going 25mph. Obviously there needs to be a hybrid approach as you describe as the current situation is not optimal.
Yes, the EUC market is a prime example. There aren't actually that many VESC EUC builds because there is so much competition it is not needed.
Regarding "drinking the kool-aid" and "the pioneer of a technology not is not often the one that sees it through to maturity", I feel like a prime example was the Boosted boards.