Ammo box waterproof vents

Hey guys,

On the board i’m currently building i’m using ammo boxes as a top mount enclosure.
Now i hear it’s a good idea to make some vents so that the whole enclosure doesn’t blow up in case of a battery fire.
Usually people that use ammo boxes as lipo storage do remove part of the gasket, but in my case i’d like to keep the whole thing waterproof.
Any idea how to do that ?

I’ve seen these and wondered how they’d fare

Claim decent waterproofing and they have solid models available of all items which is super nice.


Seriously man, i’ve been looking for thing like those for days, with no idea what to call them.
Looks great, not sure they’d be enough to vent a big ass lipo blowing up, but worst case scenario they can still pop out champagne cork style

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I wish you no evil but I would pay to see this :rofl:


You might be able to make a vent that uses this material: Hydrophobic Acoustic Mesh - Allows air to pass, but stops water – Material Sample Shop

I also found this which looks more promising, but didn’t see where you could buy it. The video looked interesting though.


IMO they would do almost nothing to relieve pressure if there was a fire unless the entire thing blew out.

Check out 4:18 and 5:38 into Mario Contino’s video to get an idea of the amount of gas being generated. I’ve seen research papers mention that up to 2 liters of gas per Ah can be created. That is 8 liters of gas just for a single Molicel P42A and a large number of cells can be creating gas.


IMO it wouldn’t allow the gases and smoke to escape fast enough. The gases and smoke would also be at very high temps and there is shrapnel and flames flying around too.

I think even if the mesh survived that it would quickly get clogged. :pensive:
Otherwise I frakkin’ love the idea of using such a material…very cool.

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Have a large hole in the can (facing away from body parts) that you cover with a blow-off panel (hot glued on?) or rubber membrane that would rupture if the pressure built up?

Or maybe something like this? Venting off the side of the can?
(edit) Though I guess water could get splashed up and in…maybe


3D print a lid with a weak point designed to fail, if you want something solid. Otherwise, swap the metal lid for flexible rubber. That’ll definitely pop


Could also have a thin plastic film behind a wire mesh in a printed housing, under most conditions it’s air tight because of the film and shielded from puncture but if there’s a lot of pressure the film bursts and vents the extra gas, one use only but if it blows you already have bigger issues


Well, the lid poping out would mean having the flames right under my nuts. I’d prefer them away from me, at least until I can get out of my bindings.

@Battery_Mooch thanks for the tips. I like the blow off panel idea, I was thinking maybe multiple small holes with rubber caps silicon-glued to them ?
It’s always a pain in the ass making big holes in steel.

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-_- I brought those up like 7 months ago and people told me I was crazy lmao

Verrrry good point!

They’re called gore vents

Your maths doesn’t add up sir :kissing_heart:


I use an ammo can to store my lipo batteries. I drilled a hole in the top an covered it with silicone servo tape. It’s waterproof. If the pressure builds up enough, it’ll burst (hopefully).

Haven’t tested it or even tried to calculate the burst pressure.

LOL, it most surely does not! Corrected to “Ah”…thank you. :smiling_face_with_three_hearts: