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Electric Skateboard v3.0: The Banana Board

Introducing my third prototype electric skateboard: the Banana Board! It’s lighter, cooler-looking, and has a longer range than the second electric skateboard. This board features a CNC cut deck, a longer range than my previous skateboard, new electronics, and a smaller electronics enclosure. Weighing in at 11 pounds, it’s also the lightest electric skateboard that I have built so far. This post will be a rough guide/build log on the Banana Board. I’ll make a video on it as soon as I upgrade my computer.

CNC deck:

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The deck I used was cut from 1/2″ scrap plywood using my dad’s homemade CNC machine. I started the design process in Photoshop, where I imported and refined a deck design. I then took the resulting image file over to Inventor, where I made a 3D model of the deck. Then I took the 3D model and brought it over to Mastercam X5, where I was able to generate the code needed to cut the deck.

Down in the garage, I loaded the .NC file into Mach3 Mill, drilled some pilot holes using a counter-sink bit, then cut the deck using a 1/4″ end bit. I repeated the process again, and ended up with two identical decks. I’m really happy with the deck style I chose; it’s the perfect balance between speed and control for an electric skateboard!

Here’s the G-Code I used to cut the deck: Deck.NC

New Electronics:

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The new circuit for the electric skateboard consists of 2x 3s 4Ah 20C Li-Po batteries hooked up in parallel in order to power a 3s ESC, rather than a 6s like on the old skateboard. This means that the top speed of the skateboard is limited to about 22km/h. However, the speed limit is a good thing. These brushless motors are more efficient at lower speeds, and even though we used less capacity batteries, we get slightly more than 10km per charge.

The receiver we used was once again the GT2B, but I’m planning on replacing it with one of my Bluetooth smartphone receivers to make it more of a commute vehicle, rather than a super fun toy (which it most certainly is!). The drive system/motor assembly was the same as the one in the electric skateboard v2.0.

Conclusion:

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This electric skateboard is a great improvement over the old versions. It’s light enough to carry, yet has enough power and endurance to really be used as a “last-mile” commute vehicle. This particular board is for my 9-year-old cousin (who’s feet are shown in the very first photograph of this post) but the board definitely has enough power to propel a growing teenager like myself, and my dad (but not at the same time!).

The next board is going to be a variation of this banana board, but it’s going to include a chain-drive, and the electronics from the previous electric skateboard. I’m going to be making very detailed videos on this project, and many of my other projects once I finish building my editing workstation PC, so be sure to subscribe to my YouTube channel if you haven’t already!

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Connecting the cells

Testing and Tabbing

As stated in the previous post, the next step is to ‘tab’ the cells. To do so, I had to check if the cells were working (had any voltage). Under the 60w bulbs in my room, each good cell got around 0.2 volts. I made sure each cell doesn’t have any cracks either, as I wanted the best cells to minimize damage later on.

I used the flux and applied it to the length of the two lines, this is where I was doing to connect both of tabbing wires. The tabbing wires are the short wires ~3mm in width. I cut them to slightly more than 16cm to compensate for the spacing between each cell.

After I fluxed, I applied some solder by heating the panel with the iron, then I applied the solder. Keep in mind that even though the cell is very fragile, it can withstand a lot of heat. I did this for the ends of each white line. After that, I applied the tab strips to the ends where I just applied the solder. I used a piece of cardboard to keep the strip down while slowly moving the iron along the wire. The animated gif below should provide better detail:

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I repeated this for each cell. If a tab wire wasn’t quite sticking I removed the wire and applied solder underneath.

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A good idea is to create a cardboard layout where you can align the cells. I used a right angle to draw lines along the length, then I measured out the width of each cell and the spacer. Since the cell was 15 cm by 8 cm and the cardboard had a thickness of 6mm, I measured 8cm, then 6mm, then 8cm and so on and so on…

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To connect the cells together I applied flux to bottom of each cell and then I applied the solder. This step was important as it is very hard to solder without the initial blob of solder. After applying the solder I folded the tab from the previous cell down, then applied heat where the white squares are located. I did this for all cells, creating two rows of solar cells. I ended up with one cell on each row that did not have contacts on the bottom. It was necessary to add two strips there as well, as they were going to be used for the bus wires.

So what the heck are bus wires anyways?

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Bus wires are the slightly thicker, wider tin wires that are used to connect strings of cells together. In my cell I used three bus wires, two for the + and – and one longer one for connecting the strings together.

Remember that the bus wires still need to connect strings in series, (+ to -) so make sure you rotate one of the strings!

Now that I connected all of my cells, it’s a good time to test them out. The 150w bulb in the bathroom was nice and provided 5-6v depending on how far away the panel was.

In the next post I will be showing you how to create a base for the panels. If you have any questions be sure to leave a comment!

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