Howdy, everyone. I’ve reached a decent stage of the planning process for my first build, and I’m now looking for any comments/criticism/advice.
This is a relatively long-term project which I’ll be doing in multiple stages - mostly out of necessity, due to being a uni student with only a part-time job I don’t expect to have this build finished until the end of the year, but no matter how long it takes, it’s gonna happen.
I’ve been interested in esk8 for a long time now, but put it off for years due to high prices and the complexity of DIY, especially since I live in New Zealand. At the start of this year, I picked up a Black Hawk Electric longboard (I know, I know). It’s been pretty damn fun, and I still enjoy it, but I’ve quickly outgrown the relatively underpowered 7S2P pack + hub motors. At this point, with a bit of damage to the motors, I don’t get anything higher than 20km/h.
The plan, then, is to rip out practically everything, and replace it with a fully custom setup. The only thing remaining will be the deck.
GOALS
The primary goal for this project is speed. Probably a common goal, of course, but 20km/h just isn’t enough for me anymore. My minimum speed target is 40km/h, with 50km/h being the ideal. As 50km/h is the speed limit on most New Zealand roads, this will make it a truly street-capable board. Torque isn’t a huge factor for me - the city I live in is about as flat as it can get.
The second is reliability. The existing Black Hawk drivetrain is okay, but it’s obviously not very good. It has an epoxy-potted black-box ESC, unknown-cell 7S2P battery pack, and relatively fragile hub motors. Replacing the whole thing will give me a better understanding of what’s actually going on under the hood, and the ability to easily replace anything that breaks.
STAGE 1
The first stage of this project involves replacing the drivetrain. I’m scrapping the existing trucks and dual hub motors, and replacing them with a single 6374 belt-drive.
I’m planning on using dickyho’s hardware kit, with a Flipsky 6374 190kV motor. The kit has 97mm wheels, a 36T wheel pulley, and a 15T motor pulley.
In terms of the electronics, I’m still slightly mixed on it. I’ve been considering Flipsky’s “Group S3” kit, which comes with the motor, an FSESC 4.12, 2.4GHz receiver, and VX1 remote. However, I know Flipsky has a somewhat mixed reputation. I’m open to any suggestions for alternate electronics.
At this point, I won’t be replacing the battery pack. While using a 7S2P pack with a system like this is a bit odd, I won’t be able to afford to build a new pack until later - that comes under Stage 2. Using the existing pack will allow me to re-use the existing enclosure and ride the board while I build everything else.
STAGE 2
This is the point where the board will properly come together. Once I have the board running on the new drive-train and electronics, I’ll start assembling the cash and materials for a new battery pack build, and a new enclosure.
The battery pack will likely be a 12S2P flat-pack design, with Molicel P42A 21700 cells. Sourcing cells is quite an issue here in New Zealand, due to air freight regulations. Thankfully, after being tipped off by a user here, I found that 18650BatteryStore stocks them for an acceptable price (about half the local price!), albeit with some high shipping prices. I considered using Samsung 30Q cells from a local supplier, but the difference in price works out to be roughly NZ$70, which IMO is acceptable for the benefits of the P42As.
I’ll likely be building the battery myself, unless I can find somebody in New Zealand to build it.
The next thing to tackle will be the enclosure. My plan is to whip up a custom CAD design once I know the dimensions of the battery, then 3D print it in ABS. Since I’m a little worried about cracks or impacts, I’ll then be applying some fiberglass cloth and resin. Hopefully, after sanding and painting, it’ll be a good-looking and strong enclosure. Additionally, I’ll be adding a silicone gasket to the deck to ensure water can’t get in. I’ll be using a GX16 connector for charging, and an XT90S loopkey.
At this point, the board should hopefully be capable of speeds around 50km/h. Before I call it “finished” though, I’ll be filling in the old drill holes, sanding down the deck, painting it, and applying a clear-coat. I’ll also be using some plain-black grip-tape, and spray painting some white stripes on it.
EXTRAS
I’m pretty interested in adding LED strip lighting to the bottom of the deck, with acceleration/braking changing the light states. For example, when accelerating, I’d like the LEDs to slowly light up in segments based on the speed - one block at 10km/h, another at 20km/h, etc, acting sort of like a speedometer. Whenever I brake, the LEDs should all change to red. I’m not entirely sure how to implement this - I imagine I’ll need a custom board sitting between the receiver and VESC that receives the throttle/brake states and adjusts the lights accordingly.
I’ll also be re-using old front and rear lights from my bike, since I often ride at night. It should provide plenty of visiblity for me in the front, and plenty of rear visiblity to people behind me, especially combined with the under LEDs.
BOM (tentative)
Hardware:
- 2x 8" trucks (dickyho)
- 4x 97mm wheels (dickyho)
- 205mm hanger (dickyho)
- motor mount (dickyho)
- 5M 36T wheel pulley (dickyho)
- 5M 15T 15mm motor pulley, 8mm bore (dickyho)
- drive belt (dickyho)
Electronics:
- Flipsky 6374 190kV motor
- FSESC 4.12 VESC
- Flipsky 2.4GHz receiver
- Flipsky VX1 remote
Battery:
- 24x Molicel P42A 21700 cells
- 12S LithiumBatteryPCB smart BMS
- 50.4V/3A YZpower charger
- 0.2mm nickel strip, fish paper, kapton tape, etc.
Enclosure:
- ABS filament
- Fiberglass cloth and resin
Let me know if you have any critique or advice. This project’s gonna take a long time, and I’ll update as I go along.