My scooter is an AC model and so has no battery tray. There is a nice gap where I assume a battery tray is normally fitted. My battery slots into here nicely.

My question, has anyone any ideas of how to fix a battery in place in this slot without welding a battery tray in and preferably without drilling holes.
A long shot I know but some sort of strap arrangement is how I envisage it. I do use the filter housing by the way so there's an outlet and hose on the other side.
Thanks