This is a simple li-ion charger without a dedicated li-ion charger IC. This circuit can be used to efficiently and intelligently charge any single cell Li-ion battery pack like mobile battery, digicam battery, etc.
Features:
- Charging via mini-USB connector which is very common.
- Charging status display by LED
- Simple circuit by using opamp, resistor, and not by any complex dedicated IC or micro-controller.
- Charges completely drained (0V) battery packs.
- Max charging current 500mA(limited by USB supply), depending on battery.
Here’s the corrected schematics and the board design of the circuit.
These works are licensed under a 
license.
Current Status: Completed and released. PCB and full kit available for buying on request.