Patent ID: 7659690

Claim:
A method for charging a battery pack comprising at least one battery of a vehicle, the method comprising: determining a battery pack reference voltage; charging the battery pack at a preselected maximum charging current until battery pack voltage reaches the battery pack reference voltage; charging the battery pack while maintaining the battery pack reference voltage until charging current decreases to a first preselected charging current reference level; charging the battery pack at the first charging current reference level for a first preselected minimum time period and then continuing charging until a time rate of change of battery pack voltage reaches a first preselected reference time rate of change; determining battery pack voltage; and whenever the battery pack voltage is less than a preselected decision voltage, charging the battery pack at a second preselected charging current reference level for a second preselected minimum time period and then continuing charging until a time rate of change of the battery pack voltage reaches a second preselected reference time rate of change.