I ordered a triangular lithium battery pack and noticed that after it was installed it could shift laterally and potentially touch the drive sprocket. Since the sprocket would likely destroy the battery and cause an unpleasant situation, I came up with this little brace to help the battery pack fit tighter on the bar. Print as many as you need to keep things centered. The bike I installed this on is a Giant Sedona from the mid 90s. Important dimensions:

Battery Width: 76mm
Bar Diameter: 32mm
Strap Width: 31mm

I searched for something like this and couldn't find anything.... hopefully this helps someone out. Credit for the idea goes to my wife who thought it up while I was trying to come up with a big complicated guard for the cogs.