Vendors are waging battles about their low-power microprocessors that can run on a coin cell for years. Some of what they claim is somewhat disingenuous; other claims are irrelevant. This class covers real-world data on what sort of battery life can be expected (based on millions of data points the author has gathered experimentally), what mitigation strategies are appropriate, what low sleep currents really mean, and other sources of leakages that will drain the cells long before the MCU does. The class specifically focuses on coin cell applications. It covers both hardware and software issues that must be addressed to maximize battery life.