Double-Oh Battery

Hardware version 2.7, Firmware version 1.0

This is the spiritual successor to the SMOL, a tiny PCB that interrupts battery output to make fun patterns. By designing around a 10mm-by-44mm LiPo cell, I've been able to add Wi-Fi connectivity, a USB connection for charging and programming, and a dangerous (but intriguing!) overvoltage mode.

The star of the show is the ESP32-PICO-D4, a 7mm-by-7mm powerhouse. It handles the wireless networking and various GPIOs.

Hardware developed in KiCad 5.1; firmware built in the Arduino IDE. Licensed/Licenced with the CERN OHL. Documentation covered by Creative Commons Attribution (CC-BY) 4.0.

Assembly, setup, installation

Bill of materials is here. An interactive HTML BOM is here. Assembly and initial setup is covered here.

Schematic

A pdf version is also available.

To do:

• Add pictures to setup/assembly instructions
• Improve the user interface
• Generate renders