The purpose of this research is to understand the behavior and expectations of mobile handset users towards energy consumption. We analyze mobile handset monitoring traces from subsequent years with N = 253 and 105, and questionnaire studies with N = 155 and 150. The data allows us to study both the actual behavior of the users and their explicit attitudes, expectations, and experiences. Additional difference to prior work is the use of longitudinal data from multiple years and a user sample that is much larger than in earlier studies. We present hypotheses drawn both from literature and from our own experience, and use the datasets to support or refute them. Our results indicate that mobile device users need more detailed and clearer information of the battery status and energy consumption. Moreover, users want to understand how different applications and services affect the energy consumption and to learn what they can do to control it. © 2011 Elsevier Ltd. All rights reserved.