Wires were added to connect the drill’s battery connectors to a 12vdc to 120vac inverter. As the bike is pedaled, the rear wheel spins the drill, which spins the drill motor creating DC voltage.

I’ve used Black & Decker “12V” (or close to it) lithium cordless drill batteries for this. The contacts are simply flat spring-loaded slots, ... those little inverters to power much.

The biggest of the bunch is the 800W PI800BB that can power things like tools, appliances, and electronics needing up to 800W of juice and this product has to be directly attached to the battery.