BattTracker: Enabling energy awareness for smartphone using Li-ion battery characteristics

Energy awareness of mobile devices with limited battery capacity can be achieved by embedding battery drain rate monitoring capability into the devices. With Li-ion battery, battery drain rate varies with temperature and battery aging, since they affect battery characteristics such as capacity and internal resistance. We develop BattTracker, an algorithm to estimate battery drain rate without knowing the exact capacity and internal resistance by incorporating the concept of effective resistance. BattTracker tracks the instantaneous battery drain rate with up to 0.5 second time granularity. Extensive evaluation with smartphones demonstrates that BattTracker accurately estimates the battery drain rate with less than 5% estimation error, thus enabling energy-aware operation of smartphones with finegrained time granularity. To the best of our knowledge, this is the first effort to estimate the instantaneous battery drain rate by considering both temperature and aging effects on the battery characteristics.