There are a number of battery manufacturers in Canon , both international and regional. The demand from energy storage and electric cars market has made this sector a highly profitable one. The manufacturers offer a number of battery variants such as backup battery, flow battery, inverter battery, nanobattery, traction battery, watch battery, water-activated battery, car battery, and photoflash battery, to name a few. Several manufacturers have their own state-of-the art facilities for the manufacture of batteries. Batteries can be broadly classified into primary batteries and secondary batteries. While batteries irreversibly transform chemical energy to electrical energy, the secondary batteries can be recharged.