Battery life state identification method

The invention provides a battery life state identification method. The battery life state identification method is used for evaluating the life state of a power battery. The method includes the following steps that: the life state of the battery is defined according to the relationship between the internal resistance of the battery and the life of the battery; parameters of a hidden Markov mode are obtained based on the terminal voltage and charging and discharging current of the power battery; the time-domain characteristic values of the terminal voltage and charging and discharging current test data of the battery system are extracted, and an extraction method does not need iterative computation, and therefore, a lot of time can be saved; and the time-domain characteristic values are introduced into the hidden Markov mode, so that forward probability can be calculated, and an equivalent inner resistance identification result is outputted according to the value of the probability. According to the life state