A Synth Zone user by the name of James Boyce let me know that you can obtain a replacement battery for the D10 and D20 from Radio Shack. Jame's email with the necessary info follows.

James Boyce Wrote .....

Since I left my question, I have found out what battery the D-10 and D-20 use internally. It is a 3 volt CR2032 Lithium. I called Roland service and asked a very nice, very helpful rep. These are less than $3.00 at Radio Shack. Pass it along. Thanks again. James Boyce