I took a tip from some of the electric people on securing their battery hatches.

I use the small magnets from Radio Shack to secure the doors, hatches, etc. on my planes. Imbed one (or more depending on the size ) in the door/hatch and one in the framework it sets into. If space for imbedding is at a minimum (such as hatches ) imbed a thin piece of steel in the hatch/door and the magnet (s) into the framework.

I have not had anything secured with the magnets come loose or off during flight, yet they are easy to open when you need access.

I get my magnets at a craft story. They are cheaper and much stronger than the ones at the local Radio Shack. Just get the extra strong ones. They also sell some magnets that will amost support their own weight The small ones even hold the canopy of my E3D during knife edge manovers and such. The canopy is rather large as it is also the battery hatch. Lots of reports of guys loosing their canopys w/ the radio shack magnets.