Low charge / low voltage nose dive on new XR?

[bryanhayn]

Got my first nose dive today on my 4th charge with about 50 miles under my belt. No road rash, just a big bruise on my hip and a bump on my head. Happened on pavement at some speed between 14-18 mph with my battery at 13%. I was in delirium mode on gemini firmware and didn't feel any pushback; the board just died. I wasn't leaning too far forward. I always make sure to be centered or slightly leaning back. I assume I nose dived because the battery voltage was too low for the given motor load. Has this happened to any of you? I don't know how I can trust this thing to work in the future when something like this happened out of nowhere.

Edit: went to the doctor yesterday and she said I have a nondisplaced left lateral 7th rib fracture. Oh well, I love the OW too much to stop riding :)

[Glyph]

@bryanhayn - one of the frustrating things about OneWheel nosedives is it can be difficult to pinpoint exactly where it went wrong. If you had witnesses, or did a careful postmortem (assuming you weren't hurt too bad) you can usually nail it down, but if you're alone and in pain, you often can't figure out exactly what happened.

This leads to a lot of theorizing, and in the OW forums, a lot of blaming the rider, or just assuming they must have been at fault. That's frustrating, because sometimes the boards (like any piece of equipment) CAN fail.

But that said, there ARE a lot of errors a rider can make, and the more inexperienced the rider, the more likely they made one of these mistakes. You know to keep weight over the wheel, not leaned forward - that's good. But another thing that can happen (especially as the board's power gets low, and 13% is getting low) is that the rider carelessly accelerated too quickly - you have to ease into acceleration, especially if going uphill or the pavement is uneven in any way or it's windy or your battery's low or you're a heavier rider. Any or all of these conditions can combine to overwhelm the board's capacity to both thrust you forward and keep you upright, and when that happens, it happens FAST. You don't have to be going at or near top speed for this to happen.

Was the board still on after the dive? Or did you have to turn it back on? If you had to turn it back on, I'd say you have an issue with the board and it needs to be looked at.

If the board was still on, sorry to say, I am going to guess you probably overaccelerated for your conditions and overwhelmed the board. This is an error a lot of new riders make. It's the error I am pretty sure I made for the first time, 256 miles in, and I fractured my humeral ball, and a year later still deal with stiffness/soreness/reduced range of motion in that shoulder because I never saw it coming and went straight down to pavement. In a weird way, I wish it had happened to me earlier at 50 miles, when I was more expecting to go down at any second and might have reacted better.

I hope this doesn't come across as blaming you, and the sad truth is, you may never know exactly what went wrong. "Overacceleration from dead stop" is what I've decided happened to me, but it's guesswork - I don't KNOW if my board was still on, because I was alone, collecting my yard sale out of a dark street with a broken arm and trying to figure out how I was going to get home and wondering if I'd throw up or black out.

But as soon as I could move my shoulder again I got back on the horse and I treat my accelerations gently and knock wood it hasn't happened again.

You say you got "a bump on your head" - get a good helmet if you don't have one, please.

Post-nosedive, I also put Fangs on my board, because I believe they would have either allowed me to recover from my nosedive and keep riding, or at least bought me a little more time to react and run it out or roll. While I have not yet had the opportunity to test that theory, anecdotal evidence from the forums, and my buddy who's had Fangs save him 3 times, suggests they are probably a good investment for the pavement rider.

[bryanhayn]

@Glyph Thanks for the awesome reply! My conclusion so far is that I over accelerated on a low battery. I was at a crosswalk and the light had just turned green. I accelerated fine about 50 feet up to cruising speed then I got the nose dive. Luckily it happened in the city at around midnight, so there were no cars near me. Two nice women helped me up and checked my pupils for dilation but I was fine. My board was still on after I crashed. I rode it home at low speed and it felt like it was working normally.

I'll be buying a helmet today...or maybe I'll just wear my full face motorcycle helmet. I definitely want to get some Fangs but they're always sold out. Is there anyplace besides https://land-surf.com where I can buy them?

[Glyph]

@bryanhayn as far as I know that's the only place to get them. Keep checking back, I guess. There are a couple other nosedive-wheel products (the Glider and Carbonsmith) out there but I have not seen them in person and they are more expensive.

Your nosedive sounds a lot like mine - I had stopped at a crosswalk to let pedestrians cross and was starting back up from there, made it about 20-30 feet and went down. I was very confused because I didn't feel like I was going very fast yet, nor did I notice any pushback (I was riding a + in Mission with about 40% battery left, and I had felt pushback before when traveling at high speed), but the conclusion I reached was overacceleration. I am very careful to always ease into acceleration now, but even being careful doesn't mean I will always remember - a common mistake would be forgetting as I rush to cross a street to beat approaching traffic (don't do this. If you'd have to rush to make it: just wait).

If I ever do this, I hope Fangs will help prevent me laying in that same street in front of oncoming traffic.

[Glyph]

@bryanhayn forgot to add - this guy actually made a good video to demo Fangs, because he's had a couple nosedives going uphill too fast. And he actually couldn't force the nosedive (couldn't get his nose down, even when trying to intentionally) until he ran his board down to about 14% battery. So I'd say you're probably onto the answer, but I do want to note that on my nosedive (Mission/+) I still had plenty of battery (around 40% IIRC), so even if you have plenty of battery left, I still would strive for easy acceleration, esp. if uphill or windy or you are heavier.

https://youtu.be/PHCn-MRfry0

[skyman88]

@Glyph @bryanhayn

If you haven't before, you should look up a voltage charge for the OW+ or XR battery types. You'll see the voltage output ~level for the majority of the usage range but when you get down near the end of the curve, it's a sharp drop. This is why the board does not perform the same when it has low battery percentage, not enough voltage in the tank to respond to a spike in demand (going up a hill, accelerating quickly, hitting a large crack, going over a root, etc...).

[raz]

yep, you got a low battery ride very easy.

[skyman88]

@raz @Glyph @bryanhayn

Granted this is for a LifePo4 (OW+) style battery but as temps drop, the battery also responds differently. Take a look at that tail end of the curve, shows how rapidly the voltage capability decays.

OW's are less likely to surge when the battery is full. Performance is constant for ~80% of the charge and the tail end drops significantly.

http://static.whitewallenergy.com/whitewallenergy/img/datasheets/lithium_battery_12v_55ah_rkl12-55_graf2.png

[oneeyedzuma]

Hi bryanhayn I wouldn't necessarily pin it to the low voltage. It could very well have been your riding position or over acceleration but keep in mind it also could have been the front pad sensor. I see a lot of people giving advice pinning this to user error but I had this same thing happen (not on low battery though) to me a month after I got my board which really shook my confidence. So I paid much closer attention to not over accelerating as everyone had advised. My advice on that is stay <16 mph and no Delrium- I don't trust it, at least with my riding style. However, after a while I noticed bizarre engine cutoffs while idling or very slow speeds which I would have written off as beginner's error had I not been riding for a while at that point so I started to pay very close attention to the front footpad sensor. One time I got a warning message on my app that said my foot had been off the front footpad for 9 seconds while traveling 10 mph which freaked me out since I only saw it later after the fact. I got some video of the engine stalls and when it got the point I didn't feel safe on it, I called FM. They had me run some inconclusive tests on it so they had me send that footpad back so they could test it. It turns out it was defective and they sent me a new one. It is SCARY to think that there are potentially more of these defective footpads out there. Knowing this now, I am still not sure if it was me pushing the board to far on that day of my big crash or the foot sensor but I haven't had similar problems sense; either random stalls or nose dives.. knock on wood.

[Glyph]

@oneeyedzuma This is good advice, there are def. reports of bad sensors out there. You can test the sensor manually with your hand and the app or by watching the lights/feeling the board engage.

My intent was not to blame the OP, just to point out what sounded likely to me based on my own experience. But you are absolutely right that it COULD be equipment failure.

There's a weird dynamic that happens with OW nosedives - inexperienced riders tend to blame the board (which, again, CAN be at fault; but, they are inexperienced, so they also may have made errors); experienced riders get frustrated at THAT, and tend to blame the rider instead.

I'd really like to see a better balance struck. Anyone who nosedives, be it their error or a board failure, needs help understanding and resolving the issue, whatever it was.

The community should try to help them, without being jerks about it (which you were not, to be clear. Thanks for another valuable perspective and troubleshooting avenue.)

[skyman88]

@Glyph Couldn't agree more with your statement.

Hopefully I'm not in the jerk category... yet.

[Glyph]

@skyman88 Not in the least, my man.