1. An apparatus for charging a target battery, the apparatus comprising: a. an interface for electrical coupling to the target battery; b. circuitry for concurrently measuring voltage and current of the target battery; c. a database for accumulating battery parameter data from a plurality of other batteries; and d. a processor adapted to recursively update a dynamic representation of the target battery based both on jointly measured voltage and current of the target battery and accumulated battery parameter data received from the database for the plurality of other batteries; and e. a current supply for supplying current for charging the target battery as governed by the processor based on the recursively updated dynamic representation of the target battery.