Starting a thread about putting Little FOCer into a Onewheel Pint.
For future reference, the build should also appear as blog posts on my website: https://riddimrider.one/
Phase one of the project is to plug the Little FOCer as it is, detect the motor, configure balancing somewhat and get the footpad sensors to work.
First thing I had to do is bypass the stock BMS for discharge (I’ll keep the BMS for now to keep the battery balanced and replace it later):
It’s a very tight fit but I managed to cram the extra XT60 connection in there.
I bought a bricked Onewheel controller and BMS pair and extracted the connector board from the controller:
This will make it very easy to connect the motor and footpad sensor using the existing connectors, which is very convenient and keeps the controller box waterproof.
Another great thing about this setup is that the controller box on the Pint can be opened with the box screwed down to the rails, all you need to do is lift the front footpad to get to the cover.
I’ve ground off the stand-offs that were in the middle of the box, that’s the spot where the Little FOCer will be mounted later. I’ve kept the ones that aren’t in the way right now, they may still come handy.
I’ve soldered an antispark XT90s connector to the Little FOCer and made a short adaptor with an 80A car audio fuse to the XT60 that comes from the battery:
Soldering wires to the motor/sensor connector board:
I’ve found the pinout here:
The sensors are wired with a pullup resistor and short to the ground on the Onewheel controller. The ground pin on the connector board is shared with the motor connector. Since on the Little FOCer there are only pulldown resistors, I’ve interrupted the ground trace that goes to the pin on the sensor connector and that stray red wire is soldered to a pad that is connected with that pin. That red wire is connected to 3.3V on the Little FOCer and the two sensor pins are connected to ADC1 and ADC2.
The two 10k pulldown resistors soldered on the Little FOCer:
It wasn’t easy soldering these, in particular one of the pads on each of those, which I assume is connected to the ground was sucking the heat really fast. I’m glad I bought a 110W soldering iron in preparation for de-soldering and flipping the caps and connectors on the FOCer.
Things ready to connect!
Aaand it’s on!
I’ve done the motor detection, set up the IMU for balancing and configured the footpads. I did a test by pressing the footpads and tilt the board around, got the board to activate and jump up as it spun the motor really fast. Enough with this wonky setup.
Next phase is taking off the heatsink of the FOCer, desolder the caps and connectors from it, and soldering them to the other side, so that I can flip the FOCer and mount it straight to the alu box bottom, heatsinking the mosfets into it. Then I’ll be able to actually close the box and put the footpad on properly.