We demonstrate how a multi-agent top-down approach can be used to interpolate between battery level measurements on a phone handset. This allows us to obtain a high fidelity trace whilst minimising the data collection overhead. We evaluate our approach using data collected by the Device Analyzer project which collects handset events and polled measurements from Android devices. The value of the multi-agent approach lies in the fact that it is able to incorporate implicit information about battery level from operating system events such as network usage. We compare our approach to interpolation using Bezier curves and show a 50 % improvement in mean error and variance.