The present inventions, in one aspect, are directed to techniques and/or circuitry to adaptively charge a battery/cell using data which is representative of a change in terminal voltage of the battery/cell. In another aspect, the present inventions are directed to techniques and/or circuitry to adaptively charge a battery/cell using data which is representative of partial and/or full relaxation time of the battery/cell. In yet another aspect the present inventions are directed to techniques and/or circuitry to determine whether the data which is representative of partial and/or full relaxation time exceeds a predetermined range and/or is greater than a predetermined value.