This is a basic battery charger controller designed by Lewis Loflin, which he plans to use with his solar panels. The charging is controlled by a mini Arduino board which in turn controls a P-Mosfet to turn ON or OFF the charging current. Two A/D channels are used to measure the input voltage from the panels and the battery voltage. Also, an ACS712 Hall effect current sensor can optionally be connected to an additional A/D Arduino port to measure the charging current.
A 3-color (or 3 LEDs) are used to indicate the charging status. Red means low or no input, Yellow stands for charging and the Green turns on when the charging is complete.
Follow this link to visit the project page.