Battery Technology is quickly evolving, as a solar back-up, storage systems, with the ultimate goal of off-grid power. Stationary application, may be easier, than motion, IMO. Most efficient/Stored power, per weight, ration. LiPo batteries. Litium Polymer, used in model airplanes. Down side, of LiPo, is a cracked battery case, exposing Lithium to air. Leading edge tech, seems to be Tesla, There are a lot of Hybrid vehicles, (I'm driving my second Prius). Most electronic devices would have LiPO batteries. IMO, Mike CT. IMO.
Edit/Add: Prius technology does regenerative electric as part of the braking system. Electric motor is reversed, downhill grade to replenish the battery. Also saves on brake pad/disk maintenance.
