US Patent 9895991 Method and apparatus estimating state of battery

A method and apparatus estimating a state of a battery are provided. A battery life estimation apparatus may charge a battery using a normal charge rate (C-rate) during a charging interval of a charging cycle and a low charge rate (C-rate) in a low-rate charging interval of the charging cycle, may compare a determined change in an electrical physical quantity of the battery over time to a reference curve, corresponding to a life of the battery, for an initial state of the battery, in the low-rate charging interval, and may estimate the life of the battery based on a result of the comparing.