Maxim MAX745 buck converter charger
No of Batteries:  1-4 series 4.2V/4.35V adjustable per battery.
Single battery voltage adjustment range: 4.1-4.4 V, covering 4.2 / 4.35 V
Charging current :  0-3.6 A  adjustable with the pot.
Input voltage:  6-20 V DC     (input voltage must be 2V higher than battery Voltage).
Default setting:  1S (4.2 V)
Dimensions :  36 * 32 * 9mm
LED indicator:  Charging red
                                Searching: red/blue