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tudordewolf

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About tudordewolf

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  1. Shortening battery wires as an upgrade/precaution?

    I did have trouble fitting just the 2x 1000uf caps for a KS-14C. The Msuper V2 has a compartment large enough for a 16-cell battery dedicated to the circuit board, which leaves plenty of room. For the record, they were 80V caps which I felt comfortable using on a 67V system (the originals were rated for 80V) and cost a little under $20 for 10 of them shipped from mouser electronics. Though its a risky trade-off, the more capacitance you have, the less you'll have to worry about voltage spikes and therefore not need as high-rated capacitors.
  2. Why do EUCs attract such ridicule?

    I would say I've had a great experience: I've been told by complete strangers, "that's awesome" (or something to that effect) every day for most of this year. My self-worth has never been better. I work downtown in DC, so there's always tourists and often school groups on their big DC trip. I've gotten a whole chorus of "whoa!"'s as if I'm performing a magic trick instead of commuting home. It's interesting how different people react: kids, with universal fascination, adults are either politely curious or completely unaffected, and older folk are again more open about showing their interest. The busy business types of DC are often too wound up in their business to even glance up, though sometimes I'll hear a conversation stall mid-sentence as I pass. As for criticisms, I've gotten one, "it's a sidewalk" from an elderly gentleman who didn't seem bothered by the cyclists going either direction, and "you're gonna kill someone!", which I think is unfair as a criticism because there's a 99% chance it would be me. I've heard, "get a bike," but that almost seemed good-natured. Part of it may be that I ride as politely as possible: even when there's plenty of space I'll slow down below 10mph to pass a pedestrian from behind, and make a point of steering in wide sweeps around people rather than zipping by within a few inches, (even though I'm quite certain of my 'envelope' and not clipping anything). After all, compared to basically every other form of transportation, EUC's have an almost negligible start/stop penalty, and can regain any lost speed in a second or two. Come to think of it, it's had a really positive effect on my psyche. A ride home from work is mentally and physically relaxing, even providing a sort of privacy as you glide along by yourself. I can take it easy to cool down or ride a bit aggressively to blow off steam. It's given me more personal freedom to get around than I've had before (finances and life make a car untenable for now), not to mention the money saved. Riding the bus to work and back over the past 6 months would've taken twice as long or more, required walking to and from the bus stations, and cost $700 just for work, not counting the parties, events, and places I've gone free of bus schedules and routes. Ridesharing would've cost more and often isn't faster once you factor in waiting for them and rush hour traffic. So, An EUC has been one of the most cost-effective purchases of my life, with unforeseen positive consequences all over the place.
  3. New KingSong 18L?

    The 858/1036 Wh battery options are interesting in that the GT2 offers the same two capacities; presumably the same arrangements of cells, 20s4p or 5p. Of course I'd place a lot more faith in the KS's build quality... For me ~1KWh hits the sweet spot of capacity and weight; any more and it loses some of the portability that's half the point of an EUC.
  4. I think part of the challenge of preventing "wild spin" is that centripetal forces are going to affect the unicycle's perspective of "down" - if it's supposed to go dead at 45 degrees of tilt but the unicycle is spinning itself in a tight circle, it is going to experience g-forces that make it think it's still mostly upright.
  5. In most cases I would think so, however these were such a snug fit that it would have been hard to put the board in without adjust them a bit to maneuver it in. That said, I'm pretty confident it's held tightly enough not to rattle around. The original capacitors weren't mounted any more securely,- then again, those capacitors are fried...
  6. The leg could be insulated, but it was far enough away from the screw that I'm not worried. The capacitors are in parallel, it has the effect of adding up their capacitance (series would add up their voltages, and they're already rated for 80v)
  7. Electric pogo stick anyone?

    I've thought about this... it could have some kind of linear solenoid in the stick, like a straightened-out hub-motor, or electromagnets at either end that just increase the force of the rebound so it's easier to keep going.
  8. This forum post has a ton of researched information and links about the interaction between a battery, ESC, and motor, particularly the role of the power-filter capacitors. The takeaway is that shortening the battery wires will always be better for the longevity of the electronics, as well as potentially improving performance. I may be wrong about this next part, but I also think that most EUC's would benefit from larger power capacitors (in the range of 4700-10,000uF; as opposed to the ~2,000uF found in most) I expect it would be better for the batteries to experience less "stutter" between charging and discharging while the unicycle starts and stops, and that the added buffer of power could actually help it handle bumps better, by providing an extra 10-15 amps in parallel with the battery pack. It'd also be important to pick capacitors with a low ESR or they won't be able to make use of their capacity. I'm considering adding a couple more on to my msuper v2, just on top of the ones already installed. Fortunately the roomy electronics compartments lends itself to this, compared to more "packed" unicycles.
  9. Important part first: Here's how I fit replacement power filter capacitors in a KS-14C. It solves the problem of constantly bending the leads when you have to access the batteries, and shortens the distance between the second capacitor and the circuit board, which increases its ability to do its job. I came into possession of a faulty KS-14C from electricunicyclereview's closing, along with a new control board and batteries for it. It would turn on and run, but had very low battery and wouldn't accept a charge. When I opened it up I saw that the power filter capacitors were blown. I put the new circuit board in, and it would boot up but not balance or light up the battery indicator. It probably just needs to be configured for the first time, but I figured that since the original board was functional and just needed new capacitors, I'd try to fix it. I realized the replacements I'd gotten were slightly skinnier, enough to fit in the circuit board compartment lying flat. I mounted them as such, put everything back together, and it works! I also replaced the battery with 2 packs, and discovered it had a few bad cells after tearing it apart. The rest are good, so they'll be useful for other EUC-related projects. In researching the repair, I discovered that the capacitors are less effective the further away they are from the MOSFETS (in terms of electrical path) It has to do with impedance and smoothing the voltage ripple - I suspect the blown capacitors contributed to damaging the battery pack, perhaps being blown during an over-voltage downhill surge that then killed a few cells without the capacitors to smooth the spikes. I also learned that the wires between the batteries and an ESC should be as short as possible, to reduce impedance (which I understand to be a sort of "lag" between the voltage dropping and the batteries providing the amps to restore it, which the capacitors are there to fill in for) SO, it follows that shortening the battery wires as much as possible and installing larger power filter capacitors would be an overall "upgrade" to unicycle electronics, their robustness and its ability to handle bumps / uneven terrain without as much pedal dip, which is better for the unicycle and the rider. Thoughts? Some designs have up to 6-8" of wire that could be removed, and according to this forum post, that would be worth doing.
  10. I'd like to chime in with an unrelated bonus to carrying a cane on an electric unicycle - you can use it to stand still wherever you want without dismounting! It takes a little practice, but with a light touch you can keep yourself from going over in either direction, and glide right off without having to "hop up" I discovered this carrying an umbrella (That's fun too, you get to feel like Mary Poppins gliding down the street)
  11. Competitive Sports?

    Quidditch! Electric unicycles would lend themselves SO well to an adaptation of that game. It's non-contact (according to the rules at least). The beaters could be throwing dodgeballs, and the snitch could be a lure hanging from a quadcopter! You could even mount brooms on the unicycles, or make it so that players have to hold a broom and play one handed for added challenge.
  12. Two axis self-balancing Electric Unicycle?

    This self-balancing stick does what you're talking about, just add a wheel to the bottom and you're all set. I think even then you'd still need both flywheels, because one can "push" against the other that way.
  13. Given that they're using identical-but-bigger BLDC motors, they could throw a gyro chip in there and have a button that makes it stand up and stay up.
  14. How much do you spend to maintain your Addiction?

    In my case, I would say that it has paid for itself on top of the time saved and fun had. I spent $220 on a generic X3 and upgraded to an msuper2 for $1000 - In 7 months I've put over 1400 miles on it, most of which is my daily commute. At under $1/mile, that beats uber or even a car if you count parking (downtown DC...), and I expect it to last at least as long as I've already had it. I went from using uber several times a week to less than once a month.
  15. I feel silly for paying $38 for an "electric unicycle" stand on ebay only for my roommate to point out that it's a guitar stand. This one looks identical for nearly half the price.
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