How to Calculate the time of Charging and Discharging of battery?
Discharge time is basically the Ah or mAh rating divided by the current.

So for a 2200mAh battery with a load that draws 300mA you have:

\$\frac{2.2}{0.3} = 7.3 hours\$*

The charge time depends on the battery chemistry and the charge current.

For NiMh, for example, this would typically be 10% of the Ah rating for 10 hours.

Other chemistries, such as Li-Ion, will be different.

*2200mAh is the same as 2.2Ah.  300mA is the same as 0.3A