Just curious...

Hmm... Seems like he used a 19 oz. bat at that age, but I do remember some teammates who had 16s. If I remember correctly, one way to make sure it's not to heavy is to have him hold the bat by the handle with one arm, and extend the arm with the bat pointed straight out (horizontal to the ground). If he can do this comfortably, then the weight is OK. If he's shaky, go lighter. My son's favorite bat in those days was a -9 Worth Insanity.

My kids, my own and other players on the teams I have coached, seem to all prefer the -9 or -10 sticks. The -13's just don't seem to work out for most ...

Most of the bats at that age are 2 1/4 in Diam.
LL rules, -9 to -13,
Senior league bats are 2 3/4 Diam.
-7 to -9.

Heres a good site to check sizes.
http://www.justbats.com/

When my boy was 9 he used a 30/19 Demarini Black Coyote. Seemed to work just great.

DP, be careful about going too light with the younger kids (e.g., 9-10YO). Some kids cannot keep the batspeed up when the ball makes contact with the super-light bats. On video, I have seen the bat actually rebound backward from the ball at contact.

The batspeed that counts is the batspeed maintained through contact. So if the bat slows considerably at contact, it doesn't matter how much batspeed was generated prior to contact.

The matter at hand is transfer of momentum, of course.

Some youngsters are strong enough to not lose too much batspeed at contact with the super-light bats. Quite a few cannot do so.

Heck, the wood bats I used growing up were probably +2 or +3.

Our experience was a lot like Texan described, we tried -12 with both boys and neither hit well with it. Both boys hit with more power and confidence with the -8 as the lighter -12 bat seemed to bounce off the ball.