Battery charger

A battery charger (10) comprising a housing (100) including a compartment (210/220) for holding battery cells (400/420), and an internal electronic charging circuit for charging battery cells (400/420) in the compartment (210/220). A heat sink (310/320) is located in close proximity to the compartment (210/220) for physical contact by battery cells (400/420) being charged to dissipate heat resulting from battery charging. The heat sink (310/320) is exposed to the outside of the housing (100) for heat dissipation, whereby fast charging is made possible.