One Fleet, Two State Machines — Firmware Architecture for GPS Trackers

A client once asked me why their "universal" GPS tracker firmware worked perfectly in bench tests but bricked half the fleet within a month. The answer was in a single line of their main loop: while ( 1 ) { read_gnss (); send_over_lte (); sleep_ms ( 30000 ); // 30s, "good enough for everything" } That loop is fine on a delivery van with a 12V battery feeding the device. On a pallet running off an 8500 mAh lithium primary cell, it drains the battery in under three weeks. Why does one GPS tracker