Various embodiments of the present technology may comprise a method and apparatus for measuring battery characteristics. In various embodiments, the apparatus comprises a lithium ion battery and a fuel gauge to monitor the resistance of the battery and the capacity of battery as it ages. The fuel gauge may perform two different methods for computing two different capacity values. The fuel gauge may utilize the capacity values from each method to determine the resistance of the battery as it ages and related battery characteristics, such as the state of health of the battery.