US Patent 8164306 Battery charge control device and marine vessel including the same

A battery charge control device for a marine vessel is arranged to control charging of a plurality of batteries, which include a main battery arranged to supply power for operating an engine of a propulsion device, and an accessory battery which is arranged to supply power for devices other than the engine. The main battery and the accessory battery are connected in parallel to a power generator attached to the engine. The charge control device includes a switching element arranged to short-circuit the power generator, a first control unit arranged to execute first control to short-circuit the power generator by driving the switching element when a voltage of the main battery exceeds a first upper limit, in a first control period, and a second control unit arranged to execute second control to short-circuit the power generator by driving the switching element when a voltage of the accessory battery exceeds a second upper limit, in a second control period which is longer than the first control period.