This is a simple but effective, dual-rate, standalone charger for Lithium Polymer batteries. It supports two different charge rates selectable with a swtich, of approximately 100mA and 500mA. The 500mA rate is good for batteries of 400 mAh and higher including the 900mAh cells sold with TeleMetrum starter kits, while the 100mA rate is more appropriate for the 110mAh cells often used with TeleMini. A standalone charger is essential for use with TeleMini since it does not have on-board charging capability.
Production units are available from the Garbee and Garbee web store.
These are photos of production version 1.1:
- Micro USB connector for power input
- 2mm JST-style connector for battery
- dual-color LED
- red when charging
- green when charge complete
- both on, or "yellow", when battery is disconnected or bad
- 1.0 x 0.4 inch board
- Hardware Features
- Microchip MCP73831 Li-ion battery charger chip
- Tools Used
- gEDA for schematic capture and PCB layout
For those who don't have ready access to the gEDA suite, here are pdf snapshots of the files for Production PCB version 2.0 in more easily readable form.