According to an example embodiment, an arrangement charges equipment batteries, for example, while the equipment is being towed by a towing vehicle. In this example application, the towing vehicle has a primary battery and a rearward-located hitch for towing a trailer that carries the equipment batteries....http://www.google.com/patents/US7193393?utm_source=gb-gplus-sharePatent US7193393 - Approach for charging multiple batteries
