In wireless sensor networks (WSN), battery energy efficiency is a crucial issue since the sensor nodes in WSNs are generally driven by nonrenewable batteries. In recent years, there has been an increasing trend of incorporating special battery characteristics into network protocol design and optimization. This paper provides the overview of battery energy consumption optimization for two specific communication tasks. To do that, we introduce a realistic node model incorporating circuit power consumptions and battery nonlinearity. Based on this model, one can choose a more battery-energy-efficient modulation scheme for the entire network. By a case study, we show that the modulation selection depends on the internode distance. Then, for specific communication links within the network, one can either use single-hop direct link communication or multi-hop communication by utilizing intermediate nodes for information relaying. Our analyses show that from the battery energy efficiency perspective, the choice of relaying depends on the transmission distance and the relay node position.