It can be done max 2 times balancing. Divide the balls into set of 3, 3 and 2.

Measure the first set of 3 balls against the other set of 3 balls.

If both are equal measure the other 2 to find the heavier one.

If not take the set of 3 balls that was heavier and measure any 2 against each other. This will give you the heavier one. But If both are equal the third ball from that set is the heavier one.

It needs 3 times of balancing in worst case and 2 times in best case