We love the efficient use of power and no project shows it better than the InfiniLED V2.
The InfiniLED V2 from BelgianEngineer is a tiny PCB barely bigger than the CR2032 battery that acts as a power supply. With a robust design using only discrete components the InfiniLED V2 will light the onboard LED whilst only consuming around 5uA! At that rate of power consumption, and if set up with a box fresh CR2032, you should see a battery lifespan of around 5 years.
Supplied assembled and with a clear acrylic case the InfiniLED V2 has strong neodymium magnets on board making it firmly mount to ferrous metal surfaces. BelgianEngineer suggests a night light for a young person or a fridge beacon guiding you to the fridge for that night time snack! Our first thought was placed next to a lock to save the inevitable poking around with a key in the dark!