Battery charge indicator using a Attiny13 microcontroller
Off-Grid Power - Solar Charge Contoller - DIYODE Magazine
Amazon.com: for USB Type C Pluggable Development Board for Attiny85/Attiny13A/Attiny25/Attiny45 Programming Editor Connector Replacement for Digispark Arduino Module (5 pcs) : Electronics
Adding A Battery Gauge To A Project With Zero Parts | Hackaday