Patent ID: 8841884

Claim:
A method of charging a rechargeable battery, comprising: providing, during a ‘bulk stage’, a regulated charge current to said battery until the voltage across said battery increases to a predetermined ‘absorption stage voltage limit’ at which time charging transitions to an ‘absorption stage’; providing, during said ‘absorption stage’, a charge current to said battery which maintains the voltage across said battery at said predetermined ‘absorption stage voltage limit’; determining when a first condition occurs, said first condition being when said charge current falls to a predetermined ‘absorption stage current threshold’ value; determining when a second condition occurs, said second condition being when the charge in ampere-hours delivered to said battery during said absorption stage rises to a predetermined ‘absorption stage charge threshold’ value; determining when a third condition occurs, said third condition being when the difference in charge between two successive fixed time intervals of equal duration becomes approximately zero; transitioning charging to a ‘float stage’ when any of said three conditions are met; and providing, during said ‘float stage’, a constant charge current to said battery such that the voltage across said battery varies with the temperature of said battery.