Patent ID: 7245107

Claim:
A method of adaptive charge control of a battery pack, comprising the steps of: (a) determining at least one of a cycle life parameter and a maximum state of charge of said battery pack, said cycle life parameter and maximum state of charge varying during a lifetime of said battery pack; (b) calculating a charge headroom from said life cycle parameter or said maximum state of charge; (c) determining a charge termination voltage level for charging said battery pack based on said maximum state of charge minus said charge headroom; (d) adaptively and only partially charging the battery pack to a first level defined by said charge termination voltage, wherein said first level is less than said maximum state of charge, said charging being terminated before said battery pack is fully charged, and (e) during said lifetime of said battery repeating steps (a)-(d), wherein said first level of said battery pack is changed based on a condition of said battery pack, and (f) allowing discharge while the state of charge of the battery pack exceeds a second level corresponding to a complete discharge level increased by an amount that is based on the cycle life parameter.