Step 1. Set up a scale with a ball on it.
2. Swish the ball to 8 inches with weight and something to hold the right distance.
3. Wait for the force to stabilize from air leaking out.
4. Post your findings in this thread:http://www.chiefdelphi.com/forums/showthread.php?threadid=142213
Of all the things to use, why did you use batteries? That’s just a horrible idea.
Why? In all reality the batteries are fine.
But metal can give you the same structure, and metal doesn’t explode or leak battery acid when it gets dropped. If that structure gets slightly out of alignment and falls, good bye like 6 batteries.