Venting Battery into vent pipe for holding tank

[Raz]

Originally Posted by mrscottyg

Raz: Is your AGM battery inside your trailer and vented to the outside?

The Optima AGM Spiral Cell battery User Guide states:

Trunk/Interior Mounting - If battery is mounted inside passenger compartment or trunk, it must be vented to outside of vehicle.

I was wondering if a sealed AGM battery that is classified as NONSPILLABLE could be safely located inside a trailer without venting, but it seems this is still not a good idea.

No, my battery is located on the tongue. We just bought a Subaru that has a low tongue weight limit so I toyed with the idea of relocation inside but was able to get my tongue weight down in other ways. Mine is a Lifeliner. Initially they were advertised as requiring no venting but I see Lifeliner has added:
Never install batteries in an unventilated compartment or a sealed compartment or sealed container.
That said they also include this safety statement in regard to using their batteries in rv's, boats and aircraft, which leads me to believe inside placement is a viable option.
Lifeline Batteries - Marine & RV Deep Cycle Batteries
Raz

[MCDenny]

No, they are not the same thing. AGM batteries have the electrolyte inside in paste form while regular batteries, whether sealed or not, have liquid electrolyte (sulphuric acid). The liquid can give off hydrogen gas when charging and even bubble out acid if overcharged, AGMs do not. All lead acid batteries self discharge just sitting there, AGMs do this 10x less than wet batteries. AGMs can sustain high current discharge (and charge) better than wet. Of course there is a downside, AGMs cost 2 to 3x as much as lead acid.

Optima is one brand, Concorde Lifeline is another with a little more capacity per pound of weight or $ of cost. There are other less well known brands as well.

I personally would not want a wet battery in the trailer with me but a sealed wet battery vented to the outside would probably be OK if thats what the budget required.

If you go with a sealed wet battery, do get one with a hose barb that enables a plastic tube to attached that would route any acid discharge overboard.

[Daniel A.]

I use an AGM battery in my diving Hookah totally sealed unit.
The compressor is on top of the battery draws 25 amp hours.
You won't get more sealed than this as the unit is water tight.

The fact is you would be hard pressed even with a vented battery to create enough H2 to be a problem the bigger issue is making sure the vent of the battery is open to allow the gas to escape the battery itself.
Just look under the hood of any car.