Do AGM batteries need to be in a vented space?

[bmonday]

My offroad trailer is still a work in progress and I'm not ready to unveil it yet.

That said, my tongue box is a military surplus medical supply crate. Something like this: http://www.sportsmansguide.com/net/cb/cb.aspx?a=336762

It's largely watertight, and, aside from some mounting holes, airtight too.

I understand AGM batteries don't emit gasses like other batteries. Do I still need to vent this box if I am going to run batteries and a charger in here?

Thanks in advance
BMonday

 

[elcoyote]

My offroad trailer is still a work in progress and I'm not ready to unveil it yet.

That said, my tongue box is a military surplus medical supply crate. Something like this: http://www.sportsmansguide.com/net/cb/cb.aspx?a=336762

It's largely watertight, and, aside from some mounting holes, airtight too.

I understand AGM batteries don't emit gasses like other batteries. Do I still need to vent this box if I am going to run batteries and a charger in here?

Thanks in advance
BMonday

Not all AGM batteries are created equal. Only a "Valve Regulated" AGM will not out-gas. Optimas BTW are NOT Valve Regulated. Some Deka and Lifeline batteries are for example the Deka 8A31DT or the Lifeline GPL-31 MT.

 

[egn]

If the valve-regulated AGM batteries are charged with the right voltage then there is practically no gas going outside.

Charging should be done with temperature compensation in order to avoid overcharging at high temperatures.

 

[Carlyle]

The NSB210FT Energy1 batteries I am using are quoted as the following:

These are known as VRLA (valve regulated lead acid) batteries and will not vent to the atmosphere unless internal case pressure reaches 5psi. This will occur due to a serious overcharge from a run away piece of equipment. In the event that this happens, all of our FT Series batteries have a remote venting feature that will allow you to connect a length of tubing (1/4”) and run the end to an outside vent.

The Outback charger/inverter really should never allow this to happen, but just in case they are in battery boxes and a gas line is run from each battery.
The bottom line, quality AGM's will off gas in catastrophic conditions if they have a pressure valve, otherwise they could be a hazard if not vented.