A method for estimating consumed battery life of at least one battery of a pitch drive mechanism of a rotor blade of a wind turbine includes monitoring, via at least one sensor, an actual temperature of the battery over a predetermined time period. The method also includes storing, via a turbine controller, the monitored actual temperatures of the battery during the predetermined time period. Further, the method includes determining, via the turbine controller, the consumed battery life as a function of the monitored actual temperatures.