Most torque converters have a stall speed around 2000 - 2500 RPM. Which also happens to be the RPM range that your vehicle normally runs at cruising speed. At a lower speed you would be simply running a viscous coupling between the engine and transmission.
Then, thereâs the obvious choice: A dynamo attached to one of the bike wheels. (These devices in general are called generators, but when attached to a bike, a generator is traditionally referred to as a dynamo.
Most dynamos are 6vac and can be replaced with 4xAAs or the 5vdc from a USB pack. You can ignore the issue about polarity as the dyno lights that I've worked are either incandescent and don't care or are LED but have built in blocking diodes and don't care. Whether you would want to do this is another issue. have a working lightning system on my bike with wired front and rear lights, powered by a dynamo. The dynamo's plastic has broken and I have repaired it several times now, but now it is FUBAR. Thinking about a replacement, I wondered if it would be possible to just connect some batteries to the dynamo cables.