Swytch Pro Battery Relocation Mod

After years of faithful service, my trusty second generation Swytch Pro stopped working. The culprit was the electrical contacts where the battery pack attached to the handlebar cradle, so as I had to get in and fix them anyway, I decided to relocate the battery to the down tube to take the weight of it off my handlebars.

The plan was to bypass the removable contacts altogether and just hardwire the controller inside the pack to the connectors which go to the motor and pedal sensor on the bike frame.

This mod only works on the 2nd generation Swytch kit - the newer kits seem a lot more involved to dismantle. The only other materials needed are a 3d printer, soldering supplies and an XT30 extension cable

Remove the battery and controller from the battery pack. The second generation Swytch made this easy as they used separate components inside a zip up bag with no glue or fiddly fasteners. The battery uses a standard XT30 connector which meant I could just buy an extension cable from Amazon to let me mount the battery further away.

I cut the connector tails off the handlebar cradle and the motor controller, and soldered the wires inside together to bypass the removable contacts. I did it all following the circuit diagram on this very handy GitHub page - I'm only using the motor and pedal assist sensor so not having to connect the brake switch cutoffs and throttle made the wiring simpler. I forgot to take photos of the soldering step (but that's probably for the best, my soldering is terrible)

I drilled out a 13 mm hole for the motor connector, an xt30 sized hole for the battery connector and 3 M4 holes to mount this Tupperware tub to the existing handlebar mount. With all the electronics stuffed inside, I could reconnect the motor, battery and PAS sensor to test it out. To make the bike rideable, I just wedged the original battery into a bottle cage on my down tube, but a more permanent and waterproof solution for this would be a good next step.

If I rode a lot in heavy rain, I might keep the Tupperware tub: it's very well waterproofed, sturdy, and it's transparent which means the original headlight can shine out through the side. It's not the most convenient thing to use though because you have to unclip the lid to set the power level, so I decided to 3D print a custom enclosure that would let me access the controls and hopefully still keep the electronics contained and dry. I measured the mounting hole locations on my prototype tub, modeled a new enclosure and printed it in high visibility yellow PETG. The enclosure has a removable lid and cutouts for the controls and headlight. Ideally they'd be water sealed with some acetate glued over the top, but for now they're layered in clear tape which should keep light rain out.