Hello everyone, because water sports are very much seasonal where I live, I designed a modular power unit which I can use all year-round, that I can quickly swap between different motors/setups. It’s waterproof and it houses the battery pack and VESC in separate slide-in inserts. I’m using one of my previous bigger builds on my ebike and paddleboard. When I’m not using the paddleboard with the fin mounted motor, I mount the power unit to the bike, plug in the hub motor and throttle, upload the pre-saved configs and it’s ready to go. However, I wanted to make a more compact one.
The enclosure is custom made out of an aluminium profile and CNC endcaps. The endcaps have a groove on the inside for a seal.
Some of the parts
It’s a 12s2p battery in a 8x3 grid configuration with Tenpower 50xg tabless cells. I used 0.3mm laser cut copper/nickel composite busbars for low resistance and high current. The BMS is wired so it’s charge only to save on space. The battery pack is then “clamped” between one of the endcaps and a carbon fiber plate with 3d printed guides. The xt30 charge and xt90 discharge connectors are panel mounted to the carbon fiber plate so it aligns and connects to the vesc insert when sliding into the aluminum profile. I’m still waiting for the heatshrink to come in so i can insulate the battery and seal it with silicone on both sides for a peace of mind.
The VESC insert also has a 3d printed guide with 4 tabs holding the 75100 VESC on the other aluminium endcap with a thermal pad between them, there is also a heatsink mounted on the outside of the endcap for additional heat dissipation. The phase connector is 3d printed with 7mm bullet connectors and then epoxied, there’s also a silicone gasket between the endcap and the connector and a seal on the outside of the connector to keep the water out. There are also 3 metal connectors and an on off switch that screw in the endcap, one for a hall sensor, the other is for charging and the third one is for a throttle. They have a gasket but i also epoxied them just to be safe.
How the two inserts connect inside the profile and the assembled power unit. The assembled unit weighs around 3kg.
Waterproof test went great with no leaks! And size comparison to the bigger enclosure mounted on the ebike. The enclosure mounted on the ebike has a 16s3p battery (also 50xg cells) with a 120A BMS and a 75200 VESC. The bigger enclosure actually fits close to a 100 cells but it works great with the 16s3p pack for now. I will make a post about it later.
As far as the remote control goes, I’m working on converting the hotrc ds600 remote that I’ve been using into a waterproof 3d printed/carbon fiber housing with a 21700 cell for longer battery life which will double as a handle for the power unit, mounted with a thumb screw to one of the endcaps. I might add a esp32 display to the remote I programmed for the ebike but decided to use my phone as a display in the end. Will post pics soon.
I’m thinking about making a limited number of kits available or a few built units in Europe. If anyone is interested, PM me.