battery box vents

[fender1234]

Hi all,

I am in the process of fitting twin batteries and x-eng split charge etc and whilst im cleaning out all the mud from the battery tray im wondering if it is possible to seal it to stop the mud getting in? im using 2 standard batteries so am basically wondering if they need to be vented?

thanks in advance

[western]

if you mean standard as in acid filled wet batteries, then the bay MUST be vented to outside the cab. or you could begin to feel very ill if you breathe in the vapours created.

[Andrew N]

You might feel more than just ill. Lead acid batteries give off hydrogen as they are charged, and unless that's vented away you get a build up of explosive gases. That's why the instructions for battery chargers always tell you to use them in a well-ventilated area.

[FridgeFreezer]

I find the vents block up with silt very easily, my solution was to make more holes in the bottom to let water & mud & fumes out. Sealing the leaks in a LR is like herding cats, best you can ever do is make a hole to let it all get out faster than it can come in.

Also as soon as you go deeper than the seat box in water it will fill up through the cover anyway, so if you seal the bottom your battery box will be like a fishtank.

[landmannnn]

I have put two big rubber grommets in the bottom of the box, the holes are drilled a bit oversized so they come out easily.

In theory if the box fills with water the grommets will pop out, anyway it keeps the worst of the silt out.

If you really wanted you could seal the box and vent it using windscreen washer tubing.

[fender1234]

looks like im just going to have to accept that everything in there will get covered in mud and water. i think i will do as Fridge says and add some drain holes at the bottom or How thick tubing would you need if you used a breather tube and raised it up high?

thanks for the advice so far everone

[landmannnn]

Interesting question. A lead acid battery doesn't generate hydrogen if charged below 14.3v, so in theory you don't need ventilation. In practice as the batteries get older the internal resistance will drive a bit of gas off.

If you charge the batteries with a cheap charger or get an alternator fault then you will be generating up to half a litre per minute....

My estimate - a 10mm ID hose will clear enough gas and be big enough to prevent silting up.