New Electric Skateboard

Posted byRandall 315 Comments on New Electric Skateboard

Happy pi day, everyone!

My skateboard was broken for the past five or six months, and rather than get it repaired, I traded it in for a new, more powerful model. For a cost of about $120, I now have a board that can go zero to 20 mph in four seconds. This is a pretty alarming speed and has finally gotten me to buy a helmet, but it also means I’m one step closer to becoming a Kourier. I just need to talk to Neal Stephenson about some engineering issues with those radial-spoke wheels …

For anyone interested in buying a board, I recommend going to eBay and looking for a cheap used one to try the idea out. My first board, a vaguely toy-like e-skateboard ($31 on eBay in 2004) had an 80-watt motor (still surprisingly powerful — it managed to tow four people at one point). I bought a few other cheap used ones, and then, having decided these things were indeed awesome, I decided to spend some more money on a proper board for getting around the city. I got a 250-watt Exkate Raptor 3.0 for $320, which I talked about in an earlier post.

This new board, a Pro Module 600, is also made by Exkate (now Altered Electric Skateboards):

The old 250-watt board was still not quite powerful enough to climb Somerville hills without complaint (I’m at the upper end of the 170-lb weight limit), but this new one has a 600-watt motor, which handles them no problem.

According to Science, 600 watts is about 80% of a horsepower.

This suggests that if you found a smallish horse (say, 75% the strength of a standard one), and started a tug-of-war using this new board, you could actually win.

This is of course dependent on friction and when the board can actually supply maximum power and so on. But let’s pretend it would work.






Edit: Taylor of Exkate posted with some technical info, and I answered some other questions in the comments. He mentions that if you want to order a board, call him (949.951.9500) and mention xkcd for free shipping (which can be significant). Disclaimer: They aren’t paying/giving me anything, they didn’t ask me to write this, etc. If you’re interested but don’t want to spend a lot yet, I recommend trawling eBay for a cheap board to try the idea out.

 

315 replies on “New Electric Skateboard”

  1. A gadget for throwing squirrels up isn’t nearly as cool as an electric skateboard.

    Who is that person?

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  2. For those interested in electric transportation (especially of the do-it-yourself variety), pay a visit to the Endless-sphere forums – there seem to be a lot of really knowledgeable people on there talking about new battery and motor technology.

    I really like the idea of having an electric-powered bike. I think that would be a really cheap, efficient way to get around town fast and could replace a car or motorcycle in many cases. Imagine being able to do 35-40mph on the road with cars, and then turn onto a bike path (dial it down to 25 or so) and keep on going. You’d get a workout too, as you’d be contributing a fraction of the power yourself by pedaling. (And if it dies or runs out of juice, hey, now it’s a bike)

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  3. Charlie: I know a guy around here who got an electric bike when his license was revoked. The big problem is batteries — he used NiMH cells and the whole thing ended up costing about $12,000. The folks at Exkate tell me that I might be able to equip this one with lithium-ion batteries for $600, giving it a 60-mile range. That might be my project later this year when these lead-acid cells start to get old.

    Thanks for the link — when I start messing with the alternate cells, I’ll check it out.

    Invisibleandpink: It’s a thing from this post 🙂

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  4. Having recently read Snow Crash, I can safely say that radial-spoke wheels are quite possibly “The only way to fly.”

    But, you know, on land.

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  7. I, for one, am trying to figure out how you don’t veer away from the weight of the horse when you slacken the line.

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  8. Chris: When I was doing robotics, we spent an afternoon trying to come up with a way to make them practical. They seem to have a lot of inherent engineering problems, including that it’s not entirely clear how something can roll with them while keeping several of them in the same spot on the ground, even if you solve the making-them-telescope-efficiently problem.

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  9. Instead of battery-powered, how about putting a flywheel on a (recumbent) bike? If you could somehow get the brakes to regen the flywheel, you could use the flywheel as: 1) stored energy that lets you easily start back up from a stop, and 2) a gyro that keeps the bike from tipping over when stopped. Now that’s Science.

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  12. I want one.

    Questions: What do you do when you reach your destination? Do you have a bike lock for it or somthing?

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  15. Andy: Yeah, actually! I got a lock that fits around the front truck. With a hex wrench you could still take it off — I’ll either just not worry about that, or drill a hole somewhere near the nose to thread the lock through.

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  17. My brother made a really ugly bike with a weedeater motor a few years back. Two ruined bikes and a useless weedeater later, he realized he had made a gas powered break…

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  18. Am I missing something? 600 watt 36 volt motor draws (nominal max) 16.6 amps, shouldn’t a 28.5AH battery last well over an hour, even after inefficiencies? The range should be well over 20 miles, not the 8-12 they are quoting. That’s only 25-37 percent efficiency :/

    And that’s assuming maximum amp draw the entire trip, with no regenerative braking (the board doesn’t have that, right?). Got a 30 mile long hill?

    Anyway, the reason I came to post was that my hobby right now is RC trucks. I have both nitro-powered and electric, and I’m intrigued with the idea of building an electric skateboard. Electric motors for these trucks can easily get past 500 watt, and if you’re willing to spend, 1200-2400 watts isn’t that hard to come by. That, and even the small nitro motors are usually ~1hp. Better ones can be in the 3-5hp range.

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  21. > Am I missing something? 600 watt 36 volt motor draws (nominal max) 16.6 amps, shouldn’t a 28.5AH battery last well over an hour, even after inefficiencies? The range should be well over 20 miles, not the 8-12 they are quoting. That’s only 25-37 percent efficiency :/

    Yeah! That’s been bugging me too, but I definitely have the board die pretty hard in well under an our of continuous riding. I followed a bike path about 3.5 miles and back (7 miles total), and for the last half-mile it had slowed down to walking pace. That was stop-and-go for a few of the miles, so not all at top efficiency, but the whole trip was still like an hour.

    I’m going to ask the folks at Exkate when I talk to them next.

    edit: I just asked them, and they said the 28.5 AH is a misprint, it’s actually 9.5, which makes it all add up.

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  24. “I’d suggest the Assateague Island miniature horses. Do not call them ponies!”

    Actually, they are ponies. Miniature horses have a height standard: maximum of 34-38 inches (82-91 cm) at the wither (depends on registry) and have the physical phenotype of horses, where as ponies have different conformation entirely. Even your referenced website concedes that they average 12- 13 hands (48-52 inches) – have primarily evolved to a smaller size and pony-like hardiness due to the poor forage on the island (see: http://en.wikipedia.org/wiki/Island_rule). Even when “properly” fed by humans, they rarely achieve ‘horse’ height – or mini height. One should know by now that xkcd readers will actually fact check and disprove drivel.

    As an aside, miniature horses make awesome seeing-eyes for blind people.

    I would, however, die to see a Fjord vs skateboard incident. Can provide a variety of smaller horses for such experimentation, including the Fjord. They would love this game once they figured out what the hell was going on.

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  25. Of course, mechanical power is basically force x speed. A tug-of-war doesn’t need much speed, just more force, so you can just win it with better gear ratios. I have a feeling the average quadruped can’t down-shift so easily.

    With a good enough gearing, and plenty of time, I think that squirrel in a running wheel would be able to win against the horse.

    Good thing too, considering the two people in the comic are busy doing other stuff now ….

    (And yes, electric motors produce more torque near stall speed – but they are producing almost no power. Torque and Force are not the same as Power…)

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  27. Re the ppl talking about electric bikes:

    They exist, and are fairly mainstream. There’s a few to be seen around Cambridge (the UK Cambridge not rhe US one, and one of the few UK towns where ppl use bikes of any sort), I think being rented out by some company. They’re not massively fast (like, 20mph top speed, I’d guess from watching them) but they’re also barely any more bulkey than normal bikes (just a kinda fat box around where the pedals’ sprocket). No idea on the range or battery life.

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  28. Hey, I was wondering what you do about getting up and down curbs… is it easy to pick up/put back down, if you got off of it would it just keep rolling until it ran out of juice? How good is it about rolling over cracks? I used a skateboard to get around in college but my apartment now is in a relatively hilly area (I only weigh 145), but moreso the curbs and cracks are more punishing. A bike is too big to lug around, and gas prices are so high.

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  29. Wow. The power adapter looks a lot like an XLR cable. Or at least that’s what the 12 pixels that compromise that tiny image make it look like.

    Seems like a silly design decision.

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  30. Does this blog comic constitute another reference to making out with yourself, ala comics 105 and 267? I think it does.

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  32. I read your other blag post about electric skateboards, and I was wondering what made you decide exkate was a better company to do business with than eglide.

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  33. Why not take a look at some the new transistor battery cells that are going on with cars, might be a little heavy but larger power supply and greater efficiency. Also you may want to open it up and check the motor efficiency by plugging it in the wall with an amp measuring tool and a small generator. You could also just strap some Jet assist rockets to it and fly 😀

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  34. How secure is the wireless controller? It seems like someone (not the rider) could have a lot of fun with a well-tuned transmitter.

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  35. So, curiously, how is the traction on the wheels? If you want to tow a pony, i imagine you’re going to need to grip the road fairly well.
    Also, comes in handy when taking tight curves to dodge airborne squirrels.

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  38. Dudes making out is great!

    Anyway, the term “horsepower” is based on sustained output of a horse. I think you’d need about 10hp to actually win at tug-of-war against a normal horse.

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  39. I liked the little comics in the posting, though, they both seem to be guys…

    Anyway, that’s pretty cool! The other day I ventured outside and ended up talking to some guy with an AWESOME gasoline powered scooter. I want both of them! 😀

    You should try making people do double-takes by having a GPS Navigation unit though. That’d be fun.

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  40. I have spent quite a few hours of free (class) time designing a nice speedo for my skateboard that’d feature a large red LED readout, inspired by YT’s board. I even went so far as to spec out the GPS chip, microcontroller, and the algorithm to merge GPS and accelerometer data. I have no idea how useful it’d be to download my exact route between classes onto a campus map every day… but I sure as hell would do it. Unfortunately I’ll be leaving school soon and I doubt that I’ll ever have need for my plank again. I guess I’ll have to switch over to making replica full scale mideval siege weapons or something.

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  42. they’re stick figures. if it upsets you that much to think someone might draw two dude stick figures making out, imagine one or both of them is a chick with short hair. or, alternatively, get over yourselves and/or grow up.

    i haven’t done that much skateboarding but wouldn’t it be hard to maintain stability at 20 mph? and then you’d start wobbling and death or at least high-speed interactions with an uncomfortably large area of pavement would ensue?

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  43. three08: Even the manliest xkcd chick has visible hair. Not that there’s anything wrong with 2 dudes making out, but come on man…

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  45. Alex: Can you prove that all the hairless stick figures in xkcd comics are male? That does seem to be the case in all the comics where gender is specified, but if some guys can have hair (http://xkcd.com/377/, http://xkcd.com/351/), why can’t some girls shave their heads? I henceforth claim this here diagram for the glorious cause of bald lesbian stick figure love!

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  46. I once rode a bicycle equipped with a chainsaw motor. How noisy is your skateboard?

    Pretty quiet — there’s a mildly noisy medium-pitch hum at low speeds, but it falls silent when you go up to full (and the motor gets noisier). Quiet enough that I can ride it on the street and it isn’t too loud.

    Hey, I was wondering what you do about getting up and down curbs… is it easy to pick up/put back down, if you got off of it would it just keep rolling until it ran out of juice? How good is it about rolling over cracks?

    It can jump down the curbs — to go up them I’m not smooth enough to kick the nose up that high so I just stop, grab the nose, lift it up, and get back on. But it’s all pretty fast. The wheels are large so it takes a pretty big crack to be a problem — has to be a couple inches wide and fairly deep. It goes up one-inch discontinuities okay. If you get off the board and/or let go of the controller, it stops pretty reliably.

    I read your other blag post about electric skateboards, and I was wondering what made you decide exkate was a better company to do business with than eglide.

    Well, Exkate has the wireless controller (they’re being asses about the patent, apparently, which is why E-Glide boards aren’t wireless. Exkate is a lot bigger and more widely bought from, and I got a general sense of better design from them. Also, E-Glide didn’t have a cheaper board in my price range.

    The Exkate folks also have a pretty negative opinion of E-Glide hardware, but of course they’re biased 🙂

    How secure is the wireless controller? It seems like someone (not the rider) could have a lot of fun with a well-tuned transmitter.

    Yeah, you could probably do that, although they sync to the nearest board when you turn them on so you can use two of them nearby. So they’re not totally open.

    Please tell me you did’nt draw two dudes making out.

    ::eyeroll::

    i haven’t done that much skateboarding but wouldn’t it be hard to maintain stability at 20 mph?

    The boards have special trucks that are good for high-speed stability. After about 10 seconds at that speed, you have a good feel for it — I never wobble.

    For perspective here, I’ve been riding these around for quite a while and have never been hurt falling off. I’ve stumbled once or twice and landed off the board on my feet. They’re really a lot safer than longboards, I think — most of the longboard accidents that I’ve read about happen because there’s no easy way to stop at high speed.

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  47. Lithium-ion sounds an unlikely choice, they’re kind of bad at high-power output. I’m thinking those are likely lithium-polymer batteries (or if they are not, they should be).

    Lithium-polymer batteries are a lot more exciting, especially with the increased risk of awesome explosions!

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  48. If it really bothers you children so much, realize that both characters are from his own blags talking about things he will/wants to do. Therefore its merely timetravel-selflove, if you’re uncomfortable with *unconditional* love.

    Happy pi day! sadly I am pieless… thankfully cookies*r^2 also.

    I’m seriously considering getting an electric skateboard, but the problem is i’ve no where to go… maybe when i move in a year or two…

    Isn’t 20mph a little excessive, especially in 4 seconds? Sounds to me like much pain waiting eagerly on the brink of existence, but maybe because i spend so much time in the virtual world that i forgot how to balance properly.

    You should use a complex series of lazers to help you manipulate the (how heavy is it?) massive board into THPS skate moves. You get bonus points for using science.

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  49. Just for clarification – it’s a typo on the AH for the Exkates.

    it’s 36V and 9.5AH… someone added both the voltage and the AH and you only get to add the voltage up in a series.

    We’ll change that in the literature shortly.

    Also, it is an XLR connector for the battery charger. The reason for this is that they’re cheap, easily available and perform the desired function. Consider it a case of “If it ain’t broke, don’t fix it”

    If you have any more techie questions, feel free to shoot me an email.

    If you’re interested in purchasing a board, give me a call. Mention XKCD and I’ll throw in free shipping.

    Thanks,
    Taylor
    Exkate
    949.951.9500
    taylor@exkate.com

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  50. Now, if you were to put this skateboard on a treadmill and turn them both on, what would happen?

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