This is what my package says:
Chargers for AC110V-240V 50Hz/60Hz, input voltage: 12V, output voltage DC4.2V
Specs say:
Input 1-110-240V
Input2-DC 12V 2A
Output 4.2V 4x500mA
Constant charge current-500mA plus/minus 10%
Constant charge voltage-4.2v plus/minus 1%
Cut-off current-60mA plus/minus 10%