I found an awesome 12 volt 5ah battery holder!.



It is made of neoprene, same stuff they make wetsuits out of, hopefully this gives it a little water resistence. At the very least, it provides a pretty cushy feeling, which might convey some impact resistence/padding.

It has a sewn in belt loop on the back, so you could ran a strap through it to attach to a rack. It also has 2 sets of quick release clips. Just using the one set of quick release clips on the back it clips perfectly to my rear RANS rack without needing anything else!

My 5ah 21 volt SLA battery fits snug inside with room at one end... perfect for a little wire and my fuse. It has an added small front pocket that can fit extra fuses and a mini-mag light (i.e. emergency backup bike light).