Well, it's been seven years since I first built the bike. Time for a new battery pack.
I found a Ford Escape Hybrid battery pack at a junk yard, bought it for $150, and brought it home.
Yesterday, I finally got to crack it open. Once I pulled out a zillion screws and DIDN'T zap myself with 300VDC, I was able to start pulling the cells.
Inside the pack is 50 sticks of 5 1.2V Sanyo NiHM "D" cells. So, those are 6V sticks. It's about 120 lbs of cells.
Full write up on my personal blog -
Deconstructing a Ford Escape Hybrid Battery Pack for the motorcycle