How can i charge 2 3.7v li-ion batteries using 1 power source.

Thanks for the help so far. Sorry didnt know that but i found the specs:
Color:Black
Size:90x90x25mm
Speed:2300rpm ±10%
Noise(dBA):19.0
Voltage:12V DC
Air flow(CFM):48
Life(hour):50000
Bearing System:Sleeve
Power(W):2.76
Material:Plastic
Wires/Connector:2wires/2x 4pin
Length of wire:20-24cm