I'm about to finish the new battery box. Just need to
put in restraints/hold-downs, and then epoxy the wood frames.
The three sides and bottom are fiberglass/gelcoat, i.e., part of
the boat. The top, 1/2 inch marine ply, will be epoxy'd also.

My plan is to put a fresh air vent near the bottom of the front
panel of the box, and another vent near the top to exhaust hydrogen
outside the boat. If you're curious, I plan to use panel mounted
cable clams for the two positive leads, the common, and
the battery charger leads.

Since I want to take the whole thing apart, if need be, I don't want
to seal the box up with glass or 5200...but planned to use silicone.
After the discussion re batteries exploding and spraying acid
around, (a bit paranoid now), I'm wondering if silicone will withstand
the acid. Anyone know for sure?

I should point out I'm also using the common plastic battery boxes, but
without the tops (lids?), so I have two boxes contained in a larger
box. Call it belt and suspenders, but the inner boxes should contain
the acid in the event of a split case.
I'm also considering using a couple of those cheapie indoor/outdoor
thermometers to provide a cross-check on battery temps.

Advice appreciated.
Norm B