Here's a real easy way to figure out charge rates.

If you have a 6000Mah battery and it's recommended to charge it at "1c" just move the decimal point on the Mah rating to the left 3 places:

Example: 4800(mah) ---> 4.800 amps

Exampe: 5600.(mah) ---> 5.600 amps

Example: 6000.(mah) ---> 6.000 amps

Example: 8000.(mah) ----> 8.000 amps

Example: 10000.(mah) ---> 10.000 amps

Now if you want to charge the batter at 2c just multiply that second number by two.

Example: 6000.(mah) ---> 6.000 amps x 2 = 12.000amps (thats a 2c charge rate for a 6000 mah battery.