Quick battery box question

[TheThom]

Hey everyone. I'm rebuilding a pop-up camper from the frame up. The folks on here were kind enough to steer me in the direction of this terrific battery box



My question: it has hole on the top AND the bottom. Do I need both of those? Do I really need to cut a 2" hole in the floor of my camper?!? Can I plug the bottom hole and let the top one be the only vent? I don't think the bottom hole would do much anyway since the battery will sit on it. I think it's just easier for them to manufacture them as one reversible piece.

Thanks (as always) for your input.

[Dale M.]

IF you do not have second hole (in floor) there will be no flow to speak of..... To have ventilation you must have place for "replacement" air to enter and since hydrogen gas is lighter than air you need a make up air source below outlet height for makeup air....

Dale

[Wobbly Wheels]

JMHO, but that vent is ridiculously oversized, even for an 8D at a full boil.
You don't need makeup air in a battery box because it's not convection that vents it - the gas is actually being produced, so you are pressurizing the space. The hydrogen, being lighter, gets 'pushed' out.

It looks like you have to disconnect the hose to open the box ?
Won't that make it cumbersome to check SG and fluid level ?

[grant whipp]

I've been using the sealed gel-cell batteries for the last several years ... no venting needed (though I DO mount them under the floor in a semi-sealed box, and try to keep them in the galley area) ... no problems! Just another possible option ...

CHEERS!

[TheThom]

I inherited a Dual Purpose 12V lead acid battery from the previous owner (I'm rebuilding a pop-up from the frame). I dumping enough money into it, but until this current battery dies, I plan on using it.

My thought was that I needed to let the bad gasses out - not necessarily provide a constant air current over the battery.

Also, the box opens in the middle. That means I can get to the battery without removing the vent. I can just remove the top half of the box.

[Martiangod]

The botton vent lets air in, but if your battery spills over, it provideds drainage 1 1/2 " hole saw, paint exposed cut, bead of sealant, screw box down. Remember that the off gassing is very corrosive, so you want to evacuate it as best as you can
Good idea to screan it also

[S. Heisley]

The botton vent lets air in, but if your battery spills over, it provideds drainage 1 1/2 " hole saw, paint exposed cut, bead of sealant, screw box down. Remember that the off gassing is very corrosive, so you want to evacuate it as best as you can
Good idea to screan it also

Chris (Martiangod) is right. If a lead-acid battery spills over, it needs somewhere 'safe' to spill to. However, I used an AGM (gel) sealed battery, like what is used on a wheelchair. I used the exact same battery box as the one that you plan on using, because the battery would be installed in the sleeping area. What I found was that even with the AGM batteries, there is a bit of gassing-off which could possibly be a problem in a small space like our tiny trailers; so, I installed the top vent to the outside and placed the bottom of the battery box on a raised, secured skeletal platform that allowed the box to sit flat yet intake air from the room. So far, it has worked well; but, remember that this method was for a sealed gel (AGM) wheelchair-style battery, not a lead-acid type. AGM batteries seem to be a tad safer and easier to work with.

[Wobbly Wheels]

FWIW, battery boxes are generally sized so that the bottom portion will capture 100% of the electrolyte in the event of a leak with the rest of the battery's case still in the box. Again though, my own experience is from the marine side of things where you do NOT want a ruptured case to drain...ever...whereas the batteries are rarely enclosed in vehicles. Personally, I'm going to stick with a sealed box so that any potential mess is contained, but that's jmho.

If yours has a hole in the bottom already then you may as well make use of it...

Definitely, AGM batteries are an improvement over sealed lead-acid (flooded) batteries but they do take a different charge curve to get the longevity out of them. Some can be installed on their side or even upside down, giving you lots of mounting options. There's some that I installed in a boat a while back that were about 6" only about 6" wide but were about 12" high and 18" long - I basically built a slideout rack for them and could pack a LOT of amp*hours into the space an 8D came out of. Not cheap though...