Night Fury | 121C Afterburner | TB Direct Drive Kit | 12S8P 30Q | Unity | Custom Enclosure
I wanted to share an Esk8 build I’m just starting to work on to see what people think about it…
First of all, I would just like to say that I’m doing a ton of firsts with this post. You can probably just assume that anything I’m doing for or on this post is a first for me.
Ok, here are my plans and progress so far.
These are the parts I am hoping to use. I have most of these in hand apart from the Unity
The other bits I’m going to figure out as I go
Some Electrical Stuff:
So my goal for this board is something that’s fun to ride, and that goes further and faster than my Wowgo.
Here are the full expected battery specs courtesy of the 3DServisas Calculator.
- The range on this build should be close to 27 FUBs.
- 50.4V at 160A peak are the numbers I’ll be basing electrical components on.
Some CAD Stuff:
I came across this Afterburner spec sheet on the 121C website that seemed legit enough to use for a CAD model.
I figure it will be fun to design my own battery and enclosure
A 12S8P fits snugly in the footprint of the deck with a channel in the middle for series connections. My plan is to 3D print each cell tray and connect each directly to the deck. I’ll sandwich in a neoprene rubber mat to help with vibration and serve as a moisture barrier.
I made sure to leave enough room for solder connections and nickel welds on ends of the cell groups.
The Afterburner deck arrived looks great. (fyi, the decals do peel of if you’re careful with an exacto knife)
For the enclosure I opted for a carbon-nylon filament based on color, strength and high melting point.
As far as i can tell, the next big step is building the battery. I’m posting this now so anyone here can see where I’m going and poke holes in my plans.
- Each 8X cell group will need to be bonded, spot-welded with nickel strip, and series wires soldered before going into the trays.
- I’ll use two 10AWG wires per series connection based on current demands
- My plan is to print TPU spacers to encase wires running between trays and (mostly) seal the sides of the trays
- Thinking of using high temp silicone to bond cell groups together and then to the trays.
- Vibration is going to be a factor. Will short wires running between cell trays need additional support
- Not sure if i am going to need additional protection around cells or if the trays are enough (i do have those fish paper sticky rings for the + terminals)?
- The Afterburner has a 6mm deck thickness. Will four 4-5mm deep threaded inserts with epoxy support a single battery tray?
- When the heck is my unity going to ship? … it never did
Should be more to come soon…
Ok update time. This project got pushed to the back burner with grad school, work, and life in general … but not today.
Some Prep Work
I decided to sand down the outside of the cell trays to smooth out layer lines and prep for painting later on. I saw another build that used a rubberized coating for a rough texture which I thought would look good here.
I also needed a way of linking each of the cell trays together and protecting wires between the cell trays. I opted to print small flexible spacers from TPU to get the job done.
The first thing I did was bond groups of 8 parallel cells together. I used a printed template with silicone beads between each of the cells to create a solid brick. These fit right into the trays I printed earlier. I also added my fishpaper rings around the positive terminals.
Once I had my groups ready, I started working on the series connections. Each was made with two strands of 10 gauge wire first cut to length and then soldered to a piece of nickle strip. Each nickle strip was then spot welded on to one of the cell group terminals. I followed this same process for the charge and +terminal balance leads.
This left me with lots of open leads that needed to be connected. I would have loved to put connectors in at this step but didn’t really have the space. I ultimately decided to just make splice connections since that seemed like the most straight forward approach. I connected as many small disjoint groups as I could early on to keep the voltage of the batter(ies) as low as I could for as long as possible. The last connection joined the 6 groups on the left with the 6 on the right.
To tidy things up a bit more, I added a layer of shrink wrap to each group to cover the batteries a bit more, pull wires in, and add an extra layer of separation between the left and right sides of the battery.
The last step was adding the balance lines for the BMS. These were tucked into the center channel along with the series connections.
ESC, BMS and Receiver:
I finally managed to get my hands on a Unity (but not the one I ordered). I also decided on a Flipsky VX2 pro remote. The VX2 receiver connects to the Unity over UART. I also connected the integrated power switch along with the power leads from the battery.
The hall sensors on the direct drive motors needed to be converted to the type of JST connector used on the Unity.
At this point I tested board and updated the firmware on the Unity. Everything seems to connect and run as expected (probably more on this later…)
Mounting to the Deck
For mounting the battery and electronic enclosures to the deck, I decided to use threaded inserts instead of drilling all the way through. I settled on brass knurled inserts for M4 machine bolts. I did a few tests with these and found that using a 13/64 inch drill bit with a drill stop will make a perfect sized hole to tap these into. I found that once these are driven in they are very secure.
The rest is making sure everything is aligned and securing each of the trays. Once I tested the enclosure mount, I took everything apart for the next steps. I cut and stuck a neoprene sheet to the bottom of the deck. This is to help seal the trays to the deck. I also added a rubberized spray coating to the sides of the trays while they were off.
That pretty much brings me up to where I’m at now. I can connect to the Unity over USB to configure the board. I checked and I have a speed readout on the VX2. I also just bought a 50.4V 4A Charger that I will need to test.
Next Steps and Observations:
- I think my bluetooth module on the Unity might be toast. I tried reflashing several times, but I can’t seem to connect anything to the Unity over bluetooth. The behavior i’m seeing is the same on this thread.
~~- One of the motors seems to be loose on the rear truck. Right now it’s making a rattling noise when I spin up the motors. ~~
- The clearances around the hub motors are pretty tight. Right now the motor phase cables are zip tied to the deck to keep them away from the spinning stuff. I need a better solution here.
- Probably other stuff i haven’t thought of
This is my first rodeo so i’m really looking forward to any feedback you guys have. First couple rides have gone well. Will upload more pix when I finally get it out on the road.