How Long Will Your ESP32 Sensor Actually Run on a Single 18650?

Daniel is building a parking spot presence sensor with an ESP32 and a single 18650 cell. He wants to know if it runs for weeks or dies in two days. This episode walks through the actual mathematics step by step — sleep currents, ultrasonic pings, LoRaWAN transmissions, voltage regulator losses, battery derating, and the killer variable of retransmissions in a concrete parking garage. The spreadsheet says 11 years. Reality says something very different. Episode #086626 — open it directly at myweirdprompts.com/086626