What could be better than a holiday ride past the palm trees and blue waters of a Mediterranean resort town? Perhaps making that ride on a long-range electric longboard of your own design will ice that particular cake.
And when we say long range, we mean it – an estimated 25 miles. The only reason [overclocker_kris] couldn’t come up with an exact number in the test drive seen below is that he got too tired to continue after mile 20. With a bit of juice left in the 64-cell battery pack, built from 18650s harvested from old laptops, the board was sure to have another five miles in it. A custom molded underslung carbon fiber enclosure houses the battery pack and electronics, including the receiver for the handheld remote control and the ESCs for the two motors. Motor mounts were fabbed from aluminum and welded to the trucks, with power transmission through timing belts to 3D-printed pulleys. It’s a good-looking build, and topping out at 22 MPH isn’t too shabby either.
We’ve covered fleets of electric longboards before, from those with entirely 3D-printed decks to one with a flexible battery pack. But we doubt any have the endurance and performance of this board.
[via r/DIY]
Cool build but getting tired from the motor doing all the work, not to bash him but he should get out of the lab more. 25 miles is nothing for long distance pushers and pumpers. Guys are now getting 300+ miles during the 24hour ultraskate.
Not everyone is a professional athlete. 20 miles is pretty remarkable for your average human being.
Don’t knock it until you try it.
Agreed. Lots of effort goes into balance… And on a previously untested prototype I can imagine extra tension in the test rider’s body.
Seems weird though, might half be vibration turning your legs to jello, because I could probably go 20 miles on a pedal bike, but have had enough after 20 miles on a moped due to arms/shoulders going numb.
I say this mostly in jest as an elitist street skater, but maybe he wasn’t physically tired. Just tired of riding long boards all together. After riding one for 20 miles it’d be pretty clear how dull it can be! If you’re not bombing hills, longboards are pretty boring. Soon as they make electric shortboards you can kickflip and ollie up curbs with, then this kinda range will excite him enough to complete the milage test!
Friendly short/long board bashing aside, this is very cool and honestly would love to ride one around now that I’m in my 40s, fat and broken. Great job man!
Bah! Shortboarders with their short attention spans!
Seriously: I used to do a pretty solid weekly push of just over 15 miles, along beautiful countryside and with a few hills built in. Took just about 1 1/2 hours, and I wouldn’t call it dull. And without the electrics, you get some exercise to boot. To each their own.
20 miles on a longboard is definitely not anything to scoff at. It’s not “athlete” material either — I can attest to that. On the other hand, it’s pretty darn good range to get on a bunch of laptop batteries.
Pushing 20 mi MANUALLY I’d say, as a skateboarder, is akin to running 8mi roughly if you are doing it pushing on level ground. Level ground, skating 1mi takes like 4 minutes if you are taking it easy even with bad bearings on a shortboard. So it’s like 1-1.3hr worst case of low intensity cardio by my estimate.
I’d say it’s not the distance really (you dont need to be even a good high school track runner, say). It’s really learning to bail and keep focus (balance) that would be limiting. I think of my sister-in-law that can crank out an ironman tri no problem, but lasts 2 hours on the mountain snowboarding – she just does not have the balance, and the falls take it out of you if you’re not used to it…
Outlast the rider indeed: If you spin through the build video on this you’ll see a complete horrorshow of shaping the battery case molding and metal parts with a completely unguarded cutoff wheel in a handheld grinder (and no apparent safety equipment).
Don’t. Ever. Do. This. If it doesn’t do you in, it may fire a shard of the fractured wheel into your friends skull across the room – google your own pictures for this. It happens.
Other comments on Reddit/DIY (the source for this article) were commenting on the battery array’s likelihood of fire and that the final build relied on unsturdy 3D printed wheel pulleys, and had open motor vents/an uncovered DB9 connector.
While the test run is impressively long and it’s a cosmetically clean build there were some significant things to think about doing better.
Don’t knock 3D printed parts, when I got my first 3D printer, I read allot about how “weak” prints are, and was planning on using it mostly for making molds to then cast metal parts. Once I got it I was blown away by the part strength and regularly use it to make end use parts.
Yep they can be surprisingly strong, as long as you take into account the axis that you’re layering on. Try to add any force on that axis and you’ll be sorry. I’ve heard that annealing the printed piece can help strengthen that bond between layers but haven’t tried it myself.
That is what surprised me the most though, the bond between layers is surprisingly strong, of course your are right and it is the weakest direction, but not my nearly as much as I thought it would be, I have only had a print break along a layer line once or twice. And if you print at the right temperature, the Z direction is ALMOST as strong as any other.
That’s the hackers way. If you’ve not burnt yourself of lost a finger or two it’s not a hack. ;)
LoL
I’m a bit concerned about those all those Li-Ion cells just wired up in serial/parallel without any balancing. If even one cell dies, it takes the whole thing with it, doesn’t it?
After a few cycles they will become unbalanced very fast because they won’t even have the same capacity if they are not balanced.
But in the imgur link he said he has a balancer connector and at least measured the capacity and paired them, so that might be okay until some cells die.
But i would advise against mixing cells with different capacity and chemistry and never make a series pack without balancing.
I would also make them easily removable and probably better use some new hobby lipos or new and matching li-ion instead of recycled 18650s.
I have to agree. DIY 18650 battery packs are a fire hazard. Heck, any lithium-ion packs are a potential hazard. As long as you charge them in your driveway or maybe inside your wood stove, it can be worth the risk. But if you just set the board down in your living room and charge it on your nice wood floors… https://www.youtube.com/watch?v=XT1B27DAATs
I dunno why people fear monger about DIY batteries. Clearly, if you are building your own pack you must have some idea of the risks involved. There isn’t some guy making youtube video tutorials on unsafe battery building. Basically everytime it comes up, someone makes sure to mention how dangerous it is. I have an 18650 bank and it’s balance charged. I charge it in my kitchen because I know it won’t blow apart. I built it so I know it was built correctly. Packs built by someone else I don’t trust, especially shady shenzen market specials.
The builder states very clearly that he balanced the packs.
Y2K want their longboard back..
If you talk to them again, could you warn them about 9/11?
great job.
Love it.
Very good build.
But why does your girlfriend only get one motor?
Yea I saw she is smaller then you, but still one motor.
And whats her board like compared to yours.
Great job all the way around.
This is my slim built esk8 (electric skateboard) http://imgur.com/a/Mjodj
I’m developing my own motor controller and it is under active development. Speed is a big factor how far you will go with a specific battery. You can check the google spreadsheet link at the end of the Imgur post for my ride performance logging.
Basically your parallel cells define your max range, while series cells define your max speed. For example, 20 cell 4S5P configuration gave me 18 km/h average speed and ~30 km range and when I upgraded the battery to 24 cell 6S4P configuration my max speed rose to 25 km/h, but my max range dropped to 24 km roughly. It seems somewhat linear and the changes line up when calculating the kinetic energies for each max speed.
Are these laptop-LiPo cells even any good for driving power motors? From what i recall, laptop-cells are not really made to be high-discharge rated, because they have other priorities like cost and capacity/volume. If you are not careful, you might overheat and destroy you cells ,especially in “stop-and-go” situations where the motors will draw max power to accelerate a lot. And as we should know by now, LiPos can fail in some pretty dangerous ways.
I would definately advise to use proper power batteries with known max. dischage specs and make shure your ESC limits the max. current draw from the packs to stay within spec.
And if you are at it and make your own LiPo pack, add a balancer in there that stays with the pack and constantly monitors the individual cells and cuts the power if something is not OK. Binning and balanced charger alone are not really enough at the power levels you have in that board.
The power system here looks pretty much the same as in off-the-shelf RC car, save for the battery pack. Despite the fact that balancer connector isn’t protected that well, it IS there, and I assume the creator is actually using it while charging. Charger seen in the video has this capability.
Regarding current draw, laptop 18650 cells are usually rated for 2C continuous discharge current, meaning that to exceed this, you need to drain the whole pack in half an hour. Authors range test showen that he can get more than 20 miles from single charge, with a top speed of 20mph. So, on average the current stays lower than 1C on average. On the other hand, during hard acceleration, the current can be massive, more than an order of magnitude greater than continuous, and will almost certainly exceed the pulsed current rating of the cells, despite how much of them are connected in parallel. I even doubt the XT90 connectors he used are up to the task here, with regards to pulsed current, especially on the connection between the whole, single pack, and the ESCs. I’d go at least with XT150 here.
Very impressive. I’d think the motor would overheat over long distances but apparently not.