# Battery Box Ventilation Question?



## Big Dreamer (Aug 6, 2010)

I want to build a battery box or use a nice rack mount enclosure I have with a glass door on it. 

I have seen pictures of some battery boxes but I would like to know what type of a fan or blower to use to get all the gasses out of the box? 

Should the vent go out the roof or could you run it out using a plastic dryer vent hood? I did not know it there is special or preferable blower. 

Would it be better to blow or suck? I think blowing could cause the gasses to escape out gaps that are not tightly sealed but would rather have the opinion of some that are doing this. 

And lastly do you run the fan all the time or have them set to kick on and off at regular intervals? 

Thanks


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## TnAndy (Sep 15, 2005)

I built the one I had before out of plywood, with a hinged top to access the batteries for watering/etc. I made the box longer than the batteries and put a 4" PVC pipe in that top end, and vented it up to the roof. Then I put a couple of those small, round, aluminum vent in the bottom of the other side end of the box. I did not use a fan, figuring the natural "chimney" action of warmer air rising would draw fresh air in the vents, and exhaust it out the PVC "stack" to the roof. ( same as it does for sewer gas on a plumbing stack in a house ). Also, hydrogen, being lighter than air, should also rise.

I think the fan would be overkill, quite honestly, in this design. 

BUT if you have to vent it ( depends on your situation ) out the wall, maybe a small fan, like a tiny computer fan, would be in order. Can't say.


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## 12vman (Feb 17, 2004)

How many batteries do you have? If you don't have a whole lot of them, don't box them in tight. Mine are on an open rack in my bedroom.


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## Big Dreamer (Aug 6, 2010)

Well right now I have one 9C12 Deka and would like to get three more. These will be out in the garage so as far as going out the roof or out the wall it will be easy either way. The roof vent sound like a good way to go. Do you get any rain in the pipe if it is going out the roof or is there a way to prevent that?


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## mightybooboo (Feb 10, 2004)

I do like your battery choice.


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## machinist (Aug 3, 2010)

I have 16 Trojan T105's in the drive-in basement garage area, and never had any concerns about a vent. They sit on an open battery cart made of 3" stainess steel angle with a plywood bottom and 8" casters so I can move them around if necessary. 

The amount of hydrogen they produce is not an issue if the space is great enough. It's a % thing. If the batteries are tightly enclosed in a space with little air, then they could generate enough hydrogen to make an explosive mixture. I am firmly against the idea of ANY sort of enclosure for that reason. It is creating a problem that doesn't need to exist, IMHO.


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## Jim-mi (May 15, 2002)

If you tightly enclose bats you will encounter more terminal corrosion than if you let the gasses dissipate in open air.

The fan would be on a voltage controlled relay so as to only come on when the bat volts are 'up'.


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## Big Dreamer (Aug 6, 2010)

I think you guys are right. This will be in a garage and the door is opened up several times a day and with the small system I have or am going to have it might not be a problem. So I think I will just build a rack or shelf to put them on for now at least. 

Thanks


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## eatmorelk (Dec 23, 2010)

My batteries are on the floor underneath my water tank in one corner of my bedroom.No problems.


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## wind power (Sep 29, 2010)

I have 16 golf cart batteries in a plywood box, and pretty much vented just like TnAndy's setup.
I wanted mine covered because I'm always doing something around them, controller, buss bar, dumploads, etc etc....if a drop a tool and it shorts out between two posts well.. it could get interesting, or a nosy cat gets a bit too close....

Essentially you could leave them in the open, in a large enough and well vetelated area... if you protect the posts well from something shorting them out and dumping DC power like a welder set on a high amp load


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## Jim-mi (May 15, 2002)

Also barriers enough to 'kid proof' the bats


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## machinist (Aug 3, 2010)

I used to work around industrial emergency power setups for security systems, some of them pretty big, with up to 24 of the huge old Gould 2 volt cells, maybe the size of 4 truck batteries each. (MUCH larger than the L16 size, probably 200+ lbs. each.) These setups were installed in major manufacturing plants. 

These were typically arranged on stairstepped racks, built of steel angle and painted with acid proof paint. Interconnection was made with copper buss bars and braided copper cables. Any bolts were stainless steel. The whole works was enclosed in one end of a room with a chain link fence enclosure, and left to vent in the open air. They commonly had some form of plastic trays under the batteries to catch any spilled electrolyte. The cage enclosure was locked, to prevent unauthorized access and did the job very well.


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## ozarkcat (Sep 8, 2004)

I drilled a hole in the back of the (plywood) box & on through the house, popped a square of window screen on the end of a 8" long piece of 1" PVC pipe & popped it through the wall. Simple, and it seems to work okay.


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## WisJim (Jan 14, 2004)

TnAndy has some good points. We use an old computer fan on top of the vent pipe and it is controlled by a relay in our inverter. Works fine.










You can see the pipe at the upper middle back of the battery box. The box has a removable front for loading the batteries, and is lined with milk-house board (plastic/fiberglass).


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