The VeloCharger Hub requires power to be supplied from a Hub Dynamo. This is fitted in the hub of the front wheel. You can purchase a hub dynamo and have it fitted to your own front wheel, which is a task best performed by your local bike shop, or you can buy a dynamo already fitted to a wheel to replace your own.
Suitable dynamos or dynamo/wheel combinations are available from a variety of sources, including Spa Cycles, Amazon, and Rose Bikes. Of course you may already have a hub dynamo fitted to your bike in which case you just have to connect up the VeloCharger using the cable supplied in the kit.
Hub dynamos are usually rated at 6volts 3watts, however the output varies considerably with speed, and can reach quite high voltages. The VeloCharger Hub is designed to cope with this variation in output. Charging will start at approximately 10mph (16km/h) and will cut off at speeds exceeding 30mph (48km/h) to protect the circuitry.
Hub dynamos require little or no maintenance or adjustment and are therefore the preferred choice for long term reliability.