Batteries play a crucial role in today’s IT and communication sectors. Yet the current design of computing and communication systems largely treat batteries as a black box, with limited understanding about their working conditions, not to mention optimal integration. In this talk, we will present our recent works on data-driven base station backup battery analysis and optimization in modern cellular communications (CIKM, e-Energy, TMC). We also strongly believe that batteryless will be the future for tiny IoT devices. We accordingly present a series of our recent works on batteryless communication and sensing, including high-throughput and multi-hop backscatter (MobiSys, MobiCom), distribution excitation (MobiSys), multi-track acoustic sensing with ambient energy (MobiCom), etc.