Battery box venting?

[Wade]

I have looked all over for a suitable answer with little luck so I thought I would try here. I am installing 2 trojan T105 for a 12v house bank.  I intend to put them in a box with my starting battery (not pictured). Each Batt is in a plastic batt box and will be secured well. The ply wood box I built is lined with flex seal. I had some and thought what the heck might work. The box is secured on the old engine location under the galley stairs.

My question is to vent? How? Or just leave open. My other batts I realize have been gassing into the engine compartment for 30yrs? I have a hot water (electric) heater and a cold machine compressor back there. I was going to build a lid and use a 2 inch pipe to vent outside near the aft of the boat.  The online literature is adamant about venting but in practice I do not believe many people bother. The other forum conversations all degrade into pissing matches about everything battery except how to actually build the vent.    Any ideas?     Wade 

[gregorygraham]

This is a very good question Wade, and one I am interested in myself.  Unfortunately, I don't have the answer.  Anyone?

[Seadogdave]

I've had my 2 batteries under a berth for the past couple of years.  I didn't think about the venting issue.  Good Question!

[Tim]

In the refit of my Ariel I moved the batteries forward into an area now designated for the head and storage. With a solar vent in the bow any escaping gases will be pulled out.

[matt195583]

My understanding of the whole battery venting issue is that to have an electrical vent pulling the gasses out would create an issue of flammable gasses passing through an electric driven fan. Electric motor + flammable gasses = BANG.

I would probably be inclined to have the solar vent blowing into the battery box with a second duct running up to a mushroom vent or the like. Or an intrinsically safe vent/suction fan ( no spark ).

Personally I use AGM batteries that don't vent unless something is really not right with the batts/charging system.