If you're charging at 1c, which means 1 x capacity, it should take around an hour. You want to charge at 1c because it's safe, and most battery's that I know of can only take 1 capacity. There are some that can take 2c, 3c, etc..
For that specific battery, you should be charging at 7.4v (2s lipo) and 8 amps. Why?
Because the amps you charge at is the capacity of the battery. So if I had a 2000 mAh 2s lipo, I would charge at 2 amps, 7.4v
So every 1000 mAh equals 1 amp. 4000 mAh= 4 amps. And so on.
Voltage depends on the amount of cells in the battery. The nominal voltage of each cell is 3.7v, so a 2 cell lipo (also known as 2s) would charge at 7.4v. A 3s, at 11.1v. And so on.
However, the charger you have is only capable of charging at 6 amps. So you won't be able to charge at 1c, it will take longer than an hour.
I don't think it should take 4 hours though. Watch a how to charge lipos with a 4 button balance charger video, it's the same process for basically all chargers.
(Last edited by Noel2 : 5.04.17 at 8:13 am)