How do I know the maximum voltage that a capacitor releases?
But what about when it charged full and release, how much voltage it
  can release ? Does it equal to the voltage rating ?


Whatever that may mean to you, "releasing voltage" is not a proper way to think of what a capacitor does.

Electric power is delivered to a capacitor when charging and electric power is supplied by a capacitor when discharging.  Thus, capacitors store electric energy.

The more energy stored by a given capacitor, the more voltage there must be across the capacitor.  In fact, the energy stored by a capacitor is proportional to the square of the voltage across:

\$W_C = \dfrac{CV^2}{2}\$

where C is the capacitance.  The greater the capacitance, the more energy stored for a given voltage.

But, real capacitors can be damaged or have their working life shortened by too much voltage.  Thus, the voltage rating of a capacitor.

To summarize, a capacitor does not release voltage, a capacitor stores and releases energy.