My best solution is 2 weighings. I figure as this:you take 6 of the balls, and weigh 3 on each side. if they weith the same, then weigh the two remaining balls to find the heavier ball.

If they are different. then weigh two balls from the heavier set of three balls. If one is heavier than the other, there’s your heavier ball. if they weigh the same, than the 3rd, unweighed ball is your heaviest ball.