- Specs
- How
- Let’s build
- Testing
I will provide all files I made and product links I used.
1. Specs:
I am a junior mechatronics engineer and also love to esk8. It so happened that I had 2000EUR to blow, so here it comes! I have already built 2 smaller boards but this time I want to go all out, over the winter there shell be no compromises, take time and money it takes.
I want my dream esk8 to be like:
- comfortable to ride
- reliable
- at least 45"
- last 100km on a full charge at good conditions
- charge to 80% under 2h
- fully programmable
- 40km/h top speed for cruising efficiently
2. How:
Find a drive solution, find a controller, estimate power consumption, calculate a battery capacity, choose the cells. Based on that lay out the pack and simultaneously choose the deck.
In favor of reliability I chose a direct drive. Torque Boards DD was my best bet but I found Boundmotor who offers a similar solution for half the prize, they were really nice in their customer service so I got their DD. The drives gives me 40km/h on an 8s setup so this is preferred. To drive them I went with the Flipsky vESC DUAL 6.6 since it checks all the marks on my list. Power consumption was estimated to be 10Wh/km with the help of experiences from r/ElectricSkateboarding (spoiler: it turned out to be pretty accurate). I needed roughly 1kWh of energy to go 100km, after extensive testing different cells (see the cell test sheet I linked at the end of the post) I settled on 120 NCR18650B cells. Now I know the deck would have to be large. Therefore I got the largest I could find, after I had roughly calculated that the battery pack can fit on it if I give my best at packing them tight.
Once everything mentioned arrived I stated laying out a CAD design with evolved into this:
one half of the battery enclosure the controller box
Cooling the components to keep them reliable for long runs was a key thought my build revolved around, I see so many DIY boards that just treat a heatsink on a controller like it was not even there this always makes me cringe. Therefore I have the controller mounted with the heatsink exposed to airflow, but protected by the underside of the deck. Also the battery is air cooled, more on this later! The other though was vibration dampening. The 4 circular mounting points at the battery and the 3 smaller ones on the controller are for rubber-metal-dampers. Those are the key to mount everything in a flexible way to keep the deck flexy and in the same way dampen vibrations on the enclosures. Once I had that idea I was especially excited to make it reality!
The battery blocks are pressfitted in the enclosure. This is made possible by exact CAD construction and 3mm thick thermal pads in between the battery and the covers of the enclosure. The heat of the cells is transferred through the pads, into a 2mm thick aluminum sheet and then to heatsinks mounted externally.
3. Let’s build
testing the fit for the controller heatsink
putting the nuts inside the 3D print for the cover screws
combining the shells
printing the covers and mounting the aluminum heat spreaders
welding and soldering the battery
mounting the controller and the drives
mounting the bumpers
test fitting the enclosures
finalizing the battery pack
getting the battery in
mounting the thermal pads
compressing
charging her up
adding dust covers
4. Testing:
6 month of busy work flew by and its spring!! Time to go for a test run, or 2, or 500km of riding! All I can say is I am happy, all the goals were met, 100km can be achieved on a flat route with no wind. The deck is flexy and smooth the motors have power for days and the battery is just massive! Everything stays cool and nothing moves. I will post more once I have new findings.
Please ask questions! The biggest honor for me would be if someday a second one this board live somewhere out there!
This files: