Def a great idea
I would try to make an enclosure for the battery if you have some materials laying around. Not sure if anything bad would happen, I'm just overly cautious.
Just out of curiosity, did you make the lid, or is that the lid for the tank and you just installed the light?
55gal Beginner FOWLR - 40lb Live Rock, 1 True Percula, 1 Sand Sifting CUC, 1 Scooter Blenny, 1 Sally LF Crab, 2 Turbo Snails, Frag Brain Coral, Tree Coral Frag, Zoanthid Colony