Well, back to the drawing board with my battery pack build. I have not finalized my build since I am still waiting on some wires and connectors. I also planned to replace the masonite sides with polyethylene pieces. However, I couldn't resist testing out the pack so I took it out for another test ride today on my e-bike.
I was intentionally not pedaling to test the capacity of the pack. I only rode about 5.6 miles since it was cold and windy. During one stretch, I rode up a moderate incline for a few minutes at about 6 mph to keep down the wind chill. I was drawing between 20 to 30 amps at that time. When I got home and opened the bike bag that holds the battery pack, I could smell some burnt plastic type of odor.
A close look at the battery pack revealed that I had melted the electrical tape on the positive and negative terminals of the wires to the controller. In the photo, I have already replaced the old tubing with new pieces but left the melted tubing near their original places. The electrical tape fused to the vinyl tubing I used to separate the tabs and left an impression of the bolt head in the vinyl. Fortunately, it did not melt through the vinyl tubing.

The nut and bolt of the negative terminal were discolored from the heat and the masonite actually started to char.

I will be adding an angle bracket to the sides to move the end terminals away from the tabs. I will probably use a thicker piece of aluminum to help as a heat sink since there is no air flow in the pack. So the lesson learned here is that there are thermal issues to be aware of with the build even at less than 30 amp loads and 10 awg wires.
On a positive note, the A123 cells with the short tabs are doing well. I rode 13.8 miles and used up 11.5ah over hilly terrain with no pedaling and averaging 9 mph. I started with a pack voltage of 41.2v and still have 39.4v left. The cells are also in balance after being discharged even though the starting bulk charge left the cells with as much as 0.13v deviation.