Battery's flat and you have no idea if it's dead or just tired. This checker tells you before you waste an hour on a charge that won't stick. Built from the Silicon Chip Magazine August 2009 design, it reads your SLA battery and lights up fair, poor, or good. You get the overlay PCB, all the electronic components, and a case with a machined, silk-screened front panel so it looks like it belongs on the bench, not in a drawer. One heads-up: you'll need a 220 µH ferrite core (LF1104) to finish the build – that one isn't in the box
