Can I replace a PowerTank battery?

It has been done, even though PowerTanks are not designed to have replaceable batteries. Please refer to these astronomy forum postings for more information:

Note: Replacing batteries, parts or entering into the PowerTank housing, voids the Celestron warranty. Celestron assumes no responsibility for such homemade power supplies, modified PowerTanks or batteries and parts from other manufacturers, or for improper use of such power supplies with Celestron or other products.

Updated 10/29/13