Best way to vent a battery box?

[Piersg]

I'm thinking of building my battery storage into the sofa that I'm making and had some questions. If I go with traditional lead acid batteries (i.e. 4 Trojan T105), I will need to seal the box and vent it to the exterior. Do I need to run a fan to extract the air, or is passive venting enough? What about heat, how much space should the batteries have?

If I go with AGM batteries, do I need to seal and vent like I do with the above batteries?

Am I better off building some sort of battery storage/box under the floor?

Decisions decisions!

Thanks

[cadillackid]

its recommended that all batteries be vented in case of over-charge.. somewhere I posted in a thread about information i had with a battery expert on the subject of venting..

with AGM batteries the main issue comes with a "what-if" scenerio in that your charger went off in never-land and overcharged the batteries. AGM batteries will exhaust if over-charged.. regular lead acid batteries are unsealed and exhaust anytime they are charged..

Christopher

[Jolly Roger]

It is better for many reasons safety wise to build and install your batteries outside of the living area.
I have seen RV,s with the batteries in the living area but the entire area under the sofa(for example) was vented to the outside which allowed water/moisture inside which ruined the flooring? The owners blamed it on the water tank next to the batteries?
I pulled the tank,tested it outside on blocks and no leaks? So I pulled the flooring in the area and you could see the water marks from the louvre's/registers leaking but the mold starting to grow around the inside edges of them should have been the sign but at first I was going off of the owners opinion until I had proof. There dime my time at the time. Wasn't my normal job. Just trying to help a neighbor?
Something to think about any open air vent into a conditioned space is sometimes positive pressure which means your losing heat/air and sometimes a negative pressure which means you taking in outside air that your heat and air have to work to over come and for a battery bank it needs to be open all the time so either build a sealed compartment in the bus that is vented or build one under side that can breathe on its own?
Food for thought.
Good luck.

[Piersg]

Thanks, I think I'm going to look into external battery storage.

[Carytowncat]

Hi,

I was fortunate to have space in the battery compartment under the bus so 2 more trojan T105 batteries along side the bus batt.
I drilled three 3" holes with a hole saw at the upper sides (hydrogen is lighter than air and rises )

Good luck!

[milkmania]

Originally Posted by Carytowncat

Hi,

I was fortunate to have space in the battery compartment under the bus so 2 more trojan T105 batteries along side the bus batt.
I drilled three 3" holes with a hole saw at the upper sides (hydrogen is lighter than air and rises )

Good luck!

How would your fumes exit out from under the skirt while sitting?

[TAOLIK]

The Roach motel did a pretty cool inside battery box.

Here's a picture of the roach motels battery box from that page.


I also built my vented battery box inside my bus at the stairwell. Since I am not qualified to tell you if that was a good or bad idea (I don't even have my batteries in there yet), I'll leave that to the judgement of yourself and others. I included a picture below, at Jack's advisal I relocated my computer fan to the other vent so it would push the air through rather than pull (to avoid a spark combusting hydrogen). . In an ideal world my out vent would be above the box, but it's not. There are 3 main reasons I built my battery box here.

1. I want my batteries easy to access, clean and maintain.
2. I want my batteries in a similar climate/temperature as myself.
3. I couldn't figure out where to mount a battery box beneath the bus which would be in accordance of the prior two ideals, nor could I find the skills, courage, or ingenuity to do so.

[roach711]

The external battery vent in the picture came from DyersRV.com but it wasn't long enough to reach my box so I connected it to a piece of sink trap so I could easily unscrew the union to remove the box lid. The vent hose is tilted slightly down so rainwater can't back up into the box. I also coated the inside of the box with fiberglass resin so the acid fumes wouldn't eat the plywood. All plywood seams are well sealed and the top has a closed cell foam gasket to keep battery fumes from eating the electronics in the same closet.

MTS Replacement Battery Box Vent Accessory Kit - Polar White - Batteries Boxes & Accessories - Batteries & Battery Supplies - Electrical

You definitely want easy access to your batteries so you can add water once in a while. The harder you use your battery bank, the more often they will need topped off. We use ours very lightly and I typically need to top them off once a year.

If you camp in cold weather batteries that are warm inside the bus will give you more power than batteries outside in the cold.

[Carytowncat]

Originally Posted by milkmania

How would your fumes exit out from under the skirt while sitting?

good point,
hmmm...

I'll toss a lit match down there every few hours to burn off the hydrogen...

My thinking is that the randown air flow from wind disperses the gas, and when i go to open the battery door i kind of fan the air a little just in case.

now ya got me thinking... I better seal all holes, a tiny bit of hydrogen make considerable BOOM!

[BusFiend]

Originally Posted by Carytowncat

hmmm...

now ya got me thinking... I better seal all holes, a tiny bit of hydrogen make considerable BOOM!

You could always name your skoolie Hindenburg!

[Piersg]

Roach I like your battery box. I stumbled across it awhile ago, but I've read so many build threads that they have blurred together and I couldn't remember where I had seen it. So the two options I'm looking at right now are either building it under part of the sofa in a sealed ventilated (to the outside) box, or buying an under trailer tool box from Northern Tool and mounting it underneath. The one thing I'm worried about in option two is whether or not the tool box can handle the weight of 4 batteries.

[KerryBeth1985]

here comes the but...


but, you guys had some good food for thought in here. i'm wondering how all of your battery box scenarios managed to pan out.

i'm getting ready to install 4 AGM batteries and i had some of the very same difficulties in attempting to mount them under the bus. steel truck boxes very expensive and can't hold the weight. having them built, expensive. mounting, expensive and very complicated, involves welding. welders don't return phone calls, are expensive, and so on and so forth. i never wanted to hear the word battery box again. then i took a deep breath and decided to get over it and put them in the cabin.

from what i'm reading here, sounds like i need to put them into a nice and tight rubbermaid tub that has a good sealing lid and then, just to be safe although they are AGM, i should perhaps put a hole in the top of the lid and run a vent pipe out the top.

so rubber tub, lid, vent pipe. this will all go at the bottom of my electrical cabinet that will contain everything else. charge controller (outback flexmax 60), breakers, and so on. should the battery tub be separated (boxed off with plywood) from the rest of the electrical?
you people rock!

[roach711]

Definitely keep your electronics away from lead-acid batteries. The inevitable fumes will corrode the bejesus out of them.

[KerryBeth1985]

no lead-acid batteries here. only AGM.

[Iceni John]

Technically, AGMs and sealed "gel cells" are also lead acid, just not with liquid acid like in a car or deep-cycle FLA battery. However, some folk on the BCM forum have had their AGMs overheat and/or burst, and they are saying that some AGM manufacturers are now wanting their AGMs to be vented. So, who knows?

It's not that difficult to make slide-out trays for batteries under the floor - I used sealed bearings running on 1" square tube, and my trays can easily support my weight when fully extended and me bouncing on their end. I prefer keeping everything heavy down low to help the bus's CoG, and to free up space inside for Other Stuff (and there's always plenty of that!). And for me with good ol' golfcart batteries, if one ever leaks it will just drip harmlessly onto the ground. No big deal.

John

[Icedog]

Ok, so I’ve read so many things on the subject of venting AGM batteries, it seems “most” people say they don’t need venting, but “just in case”. As there may have been cases where AGMs have “ burst”
So, my question is this:
If I seal my batteries in a let’s use a plastic Rubbermaid bin as an example, it’s sealed, with a vent tube on the top to outside, Where do the wires go from charge controller and inverter? Wouldn’t making another hole, say on the bottom of the box for the wires to enter, defeat the purposes of being “sealed”. Or is the bottom ok because hydrogen gas rises to the highest point, the vent tube. Would some not still get out through the hole in the bottom?

[Doktari]

If I was building the box the conduit holes for the wiring in the battery box would be as low as possible and lower than the vent hole. The vent hole would be as close to the top as possible.
Boats have these venting issues and other engine compartment venting issues. Solar energy users have been using sparkless battery vent fans for a long time. I think they are Coast Guard rated engine room safe fans. Look in the solar energy catalogs. Ive always used passive ventilation with no fan.
The gassing voltage is 14.2 VDC. When equalizing the batteries the lid is open because water level is being checked and the hydrometer is being used. So venting is not a issue. I don’t like to use automatic equalization. I like to be present when equalization is happening.