Electric skateboards (one I have) has regenerative braking and it’s amazing.
Being able to control your speed is a pretty big feature.
that's scary as hell considering the battery is likely to take physical abuse. Look at the number of fire incidents caused by drone LiPo charging. There's a reason why serious drone enthusiasts charge their batteries in special battery bags.
Started with Sub-C car packs, those sucked pretty badly. Then switched to HeCell 2/3A (~2000 mAH?) NiMH cells, those had good capacity but weren't the best discharge rates, they wouldn't do more than 20A peak or so. KAN 2/3AAs had pretty good discharge rates (could do 30-40A peak) but the capacity sucked (1100 mAH). All of these types of batteries tended to die after a season or two of flying, sometimes less than a season, they just couldn't handle that discharge.
Finally settled on Sanyo 4/5A FAUP 1950mAh cells, they were expensive as hell (2-3x as much as a cheap pack) but could handle insane amounts of discharge and had good capacity. They were rated to at least 45A continuous discharge and in practice could be pushed up to 75A peak loads without issue. For you whippersnappers, that would be roughly a 40C peak discharge, which LiPos couldn't touch at that time. They were also the only battery that ever lasted more than a season without issue, could easily get two and maybe a third with reduced life.
It looks like they're discontinued, which isn't surprising since everything has moved from NiMH to LiPo, but if you were doing really intense discharges like this, they would probably be my cell of choice. I've never seen a cell before or since that could handle that much discharge. LiPos are not always the answer.
LiIon is certainly not the answer for a fast-discharge application like this. They are not really any safer than LiPo, the casing is physically stronger but they will explode/burn when ruptured just like a LiPo, and they do not like high-discharge scenarios. Think laptops, not electric motors. Running a motor this big on a LiIon will end poorly, if you're lucky it will only be a fire.
Problem is I kept having electrical noise issues that caused my wireless to cut out. I never figured out how to reproduce it in the lab because it only seemed to happen under certain circumstances (possibly correlated to extremely heavy load, but not always). It caused some dangerous moments...
My build used a VESC X (from enertion skateboards, but seems like it was discontinued). The VESC is a nice open source high current motor controller, except the FETs they use are in a pretty dumb package, and the VESC X used an aluminum enclosure that acted as a heatsink for the DirectFETs they used.
I also used 2x 4S batteries used for scale cars, because they had an integral plastic box that stopped it from getting pelted by rocks and such (good thing I got it, because I originally mounted it using Velcro and it fucking dropped during a ride and the battery slid for like 100 feet; probably would have exploded without the plastic box).
Also, I hope the engine can go in reverse or this guy has no breaking power; and as he gets comfortable riding it, sooner or later, a surprise will happen and he will have no choice but jump ship.
The ESCs do have brakes. They make downhills easy to manage. The only problem is that, without some special components, the brakes don't function on a 100% full charge. (The brakes are regenerative, so the ESC watches the voltage and doesn't allow the motors to overcharge the batteries.) That's not a problem in 99% of cases -- it only matters if you start your trip on a large downhill.
That said, anyone learning to ride an electric skateboard should learn how to bail. You'll have to do it eventually.
I'd expect to use this 4-wheel sensor data along with the multi-axis acceleration data to calibrate the GPS, not the other way around.
See an explanation here: https://en.wikipedia.org/wiki/Automobile_handling#Yaw_and_pi...
And a 30 second visualistion here: https://www.youtube.com/watch?v=4jk9H5AB4lM
As hug mentioned, shifting weight helps. Also as you begin to catch wobbles, you can relax your stance a little bit to counteract them - but that takes practice. Finally, you simply control your speed - usually by sliding, but I can imagine on an e-board slides will be very cumbersome.
Of course if you know all of this, you probably already have realized that e-boards are barely good for anything but cruising from point A to B, and there's infinitely more breadth and depth to this sport than just that.
Source: I'm a roll cat ;)
Small nit, there are motors out there that offer resistance/braking without reversibility.
"Motors are relatively easy, just use a wrench to put the wheel in place".
This is only true if you find the right type of motor, which is not easy at all IMHO.
Batteries (x2): https://hobbyking.com/en_us/zippy-flightmax-8000mah-5s1p-30c...
BMS (optional): http://www.batterysupports.com/36v-37v-42v-10s-60a-10x-36v-l...
This is how I wired them together: https://i.imgur.com/tEI4H0E.jpg
It's been working really well for me so far.
VESC has it, for instance. I believe it’s configurable for cell count, sag, etc.
Going at those speeds may be fun and all, but you're 1 careless driver away from the hospital, unless you ride on abandoned roads.
That said, disks aren't essential for good bicycle stopping performance. Good rim brakes (like most mid or high end road bicycles) stop just as quickly as disk brakes in dry conditions. Rim brakes are not really an option for long boards, though.
Sliding/skidding (where the board is manoeuvred in the direction perpendicular to the movement) will make you loose speed pretty quickly.
Apart from that motor can be used to brake. Not sure what exactly is needed for it, but a DIY board I rode once had a dual trigger on the remote, one direction for moving forward, the other one for braking. Pretty convenient though won't stop you as quick as some friction brake.
lack of handlebars too.
That is only a problem if you either don't know how to steer with the board, or are trying to take sharp turns at too high speed. Both conditions which are equally true for other vehicles, main difference being some vehicles will be able to turn sharper than others given the same speed. And some are easier to control than others. But enough skill can deal with that.
Yeah, but it has the disadvantage of wearing out the wheel surface and requiring some technique. Any asshole can pretty a brake lever, and brake pads are cheaper than wheels.
> Apart from that motor can be used to brake.
It can be iff the controller is configured to. I thought I saw another comment mentioning this article's device is only rigged to go forward. I agree with you that an electric motor might be a sufficient brake for this application (at least, better than nothing).
> Pretty convenient though won't stop you as quick as some friction brake.
Yeah, it's hard to beat the mechanical simplicity.
> [lack of handlebars] is only a problem if you either don't know how to steer with the board, or are trying to take sharp turns at too high speed
I was talking about braking performance, actually. Handlebars help you throw your weight back and keep it in the right place for rapid braking.
I don't know how you'd mount a rim brake on a tiny longboard wheel.
Disk brakes seem feasible.
I'm not a long board person, I don't know what the state of the art is here.
Instant flying lesson.
It's fantastic, and the creator/designer is a great guy who is open to helping out tinkerers.
It's one of the cheapest off-the-shelf ways to move a bigger hobbyist motor with encoder support that I've found. Nothing but love for it.
ps: anybody here owns a gyrowheel ?
If you're worried about scrapes throw on a motorcycle jacket. But if you know how to fall, 40-50km/h is manageable without gear -- aside from the mandatory helmet.
My issue with the powered boards is that the motor is both engine and brake - they don't coast when you let off the throttle. With a longboard, coasting is all the fun!
I suppose it would be possible to modify the linkage between motor and wheels to be one way (drive) only? Kind of like a freewheel on a bicycle?
Very easy to source parts, could buy second hand. Could even just friction drive the wheel with the drill!
You mean for legal reasons? ;-)
I've never been much of a skater. But I've always preferred sliding on my side/butt to flopping around.
1. learn to ride a non-powered skateboard or longboard first. I guarantee you, you do not have the balance or skills to ride a longboard at 10kph off the bat, let alone 50kph. I've snowboarded and wakeboarded for a significant chunk of my life and I'm telling you, longboarding, especially fast longboarding, is not an easy skill to master, let alone pick up as a twenty-something.
2. allsunny's comment on learning to fall is spot on. You need to know, instinctively, how to bail at different speeds. At certain speeds and obstacles you can run off, at others you have to tuck and roll, still others you will rely on your knee pads or elbow pads to protect you from impact. allsunny's comment is spot on for other reasons but for now I want to move on to...
3. protection! Always wear your protective gear! I wear wrist guards, knee guards, elbow guards, and a helmet (not full face, unfortunately), every time I ride. I don't care how good you are, if you are in your mid twenties and older, a fall on concrete is really going to mess you up. Not that it doesn't mess you up when you're a kid, just that kids have a greater potential to bounce back from these things...
OK, now on to the article itself. There's a lot left unsaid, leaving you with the false impression that you have a proper and informative guide. Unfortunately, it barely scratches the surface.
(A) Hub vs belt: hubs have more cons than just heat. Hub motors tend to get really beaten up since your motors are taking the impact of the terrain. The urethane, or "tyre" part of the hub, is also typically not easily replaceable, falls off easily, or wears badly. That's kind of changing now but for the most part if you get a cheap hub you're going to have to replace the whole thing. Furthermore, the urethane is typically very thin around hub motors and your ride quality is going to suffer as more vibrations are transmitted up.
Hubs are really quiet, though.
Belt drives have many advantages. The motors get beat up less (unless you don't have enough clearance). You can "gear up" or "gear down" a belt drive (albeit not while in motion), giving you more speed and torque options. The article makes a big deal about dust and dirt and swapping belts but most belt drives have some kind of cover and belts are cheap to replace. Most importantly, you can buy wheels from companies who actually know what they're doing in terms of urethane formulation, grip, comfort, etc. You have options with a belt drive.
They can be really noisy, though.
Remember if you get a belt drive that you need a way to maintain tension. If your kit doesn't let you do so (e.g. diyeboard kits), it's... well it's not worthless, but you'll be swapping belts out a lot.
(B) ESCs: there are ESCs, and there are ESCs. The VESC the article author mentions is indeed open source hardware and firmware, but the quality of the hardware you get is really hit and miss depending on who you buy it from - some VESC hardware cannot run in certain firmware-settable modes and will go up in flames if you try (look up FOC). Furthermore, there are so many versions of the hardware out there that it can be a nightmare to find the compatible firmware for it. And finally they're usually expensive as.
On the other hand, the cheap chineseum ESCs have their own set of problems and limitations. While cheap, they are typically not as configurable as VESCs, and sometimes lock you in component wise to the vendor's radio control system, drive and battery combo.
(C) Batteries: do not buy cheap eBay hobby batteries. I've played with these in the context of RC buggies, planes and drones, and they are really hit and miss. It is fine in the context of RC toys which you play with in a safe environment and never for more than a few minutes at a go, it's not so fine in the context of a moving EV you're standing on going at 50kph, being constantly hammered by road conditions and put out in the hot sun for half an hour to hours at a time. Unless you have taken appropriate precautions and screened the batteries and otherwise know what you're doing, I wouldn't give them a second glance.
You can look up forums for reliable battery suppliers and make your own cells or buy from those. If you want to go the DIY route, GA cells apparently do pretty well, but I wouldn't put a pack together without thinking about cell-level fusing, having either special soldering equipment or a spot welding setup, strain relief, wire gauge selection, etc. If you set it up wrong, you're going to end up with too much current running through too thin a conductor and having them glow with the heat under load. I've seen it. It's cool, but also scary... mostly scary.
(D) Oh yeah, you're gonna need a battery charger. What do you mean, you don't have an adjustable chemistry battery charger just lying around at home so you can make a choice from a variety of available battery chemistries?
Alternatively you can source a battery management system which is a circuit matched for your battery chemistry, and just plug it in to a properly set up power supply. But then you have to ensure the power draw of the drive system is set up for it.
That said, one potential advantage of having a battery management system is the ability for you to take advantage of regenerative braking capabilities of your ESC safely.
(E) Remote control. The article didn't mention this, but you're going to need one. Please don't buy a bluetooth controller, a signal hiccup at 50kph and your skin could be a smear on the floor.
Speaking of hiccups, you oughta determine, and set, the failsafe behaviour on your remote controlled EV. The typical failsafe mode is to freeroll, which means if it fails you'd better be able to ride and stop your board without having to rely on the electric crutches. Callback to allsunny's comment.
(F) Deck, wheels and trucks. So you're putting together your 50kph drive and decide to slap it on a donor deck. So easy amirite?
For heaven's sake don't do this. Longboard decks come in many shapes and sizes. Again, if you're the kind to have ridden around on non-electric skateboards or longboards, you'll have a very good idea of the available options. If not, you have to do your research. The kind of setup that is fun to ride at 10kph is decidedly deadly at 50kph (look up "speed wobble"). The wheelbase, deck shape (both lengthwise and cross-sectionally), ground clearance, softness of wheels, width of truck, stiffness of bushing, geometry of truck, etc., all make a difference. There is a fair mix of personal preference and objective necessities too.
(G) Putting it all together. It's not a PC, you can't just plug in the components and have them work. You'll want to weatherproof the components somewhat, protect them from impacts. There are also miscellaneous parts you may want or need like switches, anti-spark connectors, battery level indicators, etc.
One thing often missed in assembly, for e.g., is that people buy cool looking carbon fibre decks, crowd their receiver next to the dense batteries or high current wires, and then wonder why their low powered radio transmitter and receiver only works intermittently. Not all radios, and not all decks, but some.
In conclusion: there are a whole lot of miscellaneous matters that aren't mentioned in the post and I didn't want people reading it to think it was going to be a single-blog-post level of simplicity to jump on a 50kph electric skateboard and off you go.
Last word, I promise: 50kph is scary. All of you downhill longboarders who have earned your way through the school of hard knocks know this. For the rest of us, 20-25kph is plenty fast and hard to react on if you haven't learnt to ride on a non-powered longboard or skateboard. Have fun, and take it easy!
Tired of writing, the main things I wanted to point out are that electric board drivers look like assholes and eletric skateboards are retarded. It's as simple as that. Stop using these things and learn to skate
Also, electric skateboards look hella fun to me.
Edit: This post reminds me of people laughing at me and telling me I hold my board wrong, because I 'mall grab'. Why can't you just be happy that people want to ride a board, there's no need to be a snob about it.
For the record, I don't hate on longboards in any way. My point was that it seems that eboards take away from the actual skating experience. It's not a matter of doing tricks and such, but more about the act of skating. The balance of body with the board against the force your body exerts, the feeling of the momentum gained by said force, the ground feel between you and the board in combination with the pushing foot with ground, and the control and freedom that comes with it. My feeling is that electric skateboards take away from the feeling that comes with skating, which is what makes the experience for most who do. But from observation it also seems to handicap some (not all), seeing that many appear to be off balance and unable to really control their electric boards when needing to come to full/immediate stops.
But again I do like your counter point of it being a mode of transportation that's like a bike in terms of speed and energy costs, but allows for the rider the convenience of picking up and moving along
It’s just a different thing, get over it!