Battery venting

[bohemian]

Here's one for you.
When the battery is venting off gasses do these gasses sink or float?
Should I put a vent at the bottom or the top of my battery enclosure.
And what would be considered the least amount of venting I would need to be safe. I'm using a size 27 battery.
Wayne

[Dale M.]

Batteries when venting produce hydrogen gas (H). Hydrogen has a specific gravity of 0.06960 (air =1) makes it lighter than air...

So it rises in earths "standard " air column.... This is also why it was used as a "Lifting gas" for dirigibles....

I would put in two vents one near top, one near bottom.... "Convection" will do a lot to "vent" tongue box, and keep it fresh and dry....


Dale

[proformance]

IMO......

It is not just an issue of having a hole to vent, you need to evacuate the gasses by having air circulate through the enclosure. I recommend placing two holes in your enclosure, an exit hole near the battery and an entrance hole on the opposing side. Add a computer fan to the inside of the entrance hole so the fan draws fresh air into the enclosure. Optimally, place the entrance hole opposite the battery and high up on the enclosure. Then place the exit hole in the floor opposite side of the battery from the fan so the corrosive gasses exit out the bottom of the enclosure/trailer. But, you can actually place both holes in the bottom, sides, front anywhere you feel are convenient and out of the way as long as they are somewhat across from one another to create a cross-ventilation. Just try to keep in mind that you are trying reduce and/or eliminate the concentration and possible exposure of yourself and other items to the corrosive gasses. Add a nice slotted cover over the outside of the holes to prevent rain from entering. Again, be sure to install the fan so that it draws fresh air in so that the corrosive gasses are not passing through the fan.

Proper control of the fan,

The fan only needs to operate when gassing occurs, which is when the battery is in excess of approx 13.6V., basically when the battery is under charging conditions. To accomplish this in a manner that allows the fan to operate seamlessly (no interaction from you) I recommend installing a batter isolator to control the fan operation in/or about the trailer battery enclosure.

Proper installation of a battery isolator to accomplish this task requires wiring your trailer battery POS to the Battery-A Terminal of the isolator, and the computer fan POS to the Battery-B Terminal of the isolator. Wire all POS charging sources (your tow vehicle and any other battery charging device you may use) to the Alternator Terminal of the isolator. All GND wires need to tie to a common location (Batt-Neg and/or chassis GND). Wiring in this manner will activate the fan only when power is applied to to the Alternator terminal of the battery isolator. Basically preventing your fan from running when not required, and discharging your trailer battery.

[starleen2]

Batteries vent differently. You can't let your Battery’s venting control you or your actions. Here are some tips for battery venting.

1. Simply Walk away and let it vent from whatever is angering your battery.

2. Yell at your battery while it’s venting – it will make you feel so much better too.

3. Instead of venting, meditate with the battery

4. If your battery is prone to venting often – do not let it go too far – it will soon try to destroy thing – over even blow up. While this might relieve the stress on the battery – YOU will be one to pick up the pieces

Really the above posts have excellent ideas

[Steve_Cox]

Batteries vent differently. You can't let your Battery’s venting control you or your actions. Here are some tips for battery venting.

1. Simply Walk away and let it vent from whatever is angering your battery.

2. Yell at your battery while it’s venting – it will make you feel so much better too.

3. Instead of venting, meditate with the battery

4. If your battery is prone to venting often – do not let it go too far – it will soon try to destroy thing – over even blow up. While this might relieve the stress on the battery – YOU will be one to pick up the pieces

Really the above posts have excellent ideas

I think I see a sermon on the horizon...

Accentuate the Positive, it is best to avoid the Negative side that is where most of the venting occurs.

[Shadow Catcher]

Vented battery boxes are available. The battery had better not be venting much or you are boiling the battery. Or you can use n AGM which is recombinent and does not vent much.

[mikeschn]

I've had a battery blow up in my face. That was no fun.

So I'm all for venting, the more the merrier. A vent on the bottom! A vent on the top!

But I really like the AGM batteries!

Mike...

[bohemian]

Mike if you dont mind, what was the cause of the battery blow up.
Wayne

[mikeschn]

The battery was in my car. The car wouldn't start. I put jumper cables on it. The spark caused the explosion.

I was very fortunate in that most of the sharp pieces blew off to the side.

Mike...

[bdosborn]

Ran across this awhile ago but forgot to post it. Dunno if its snake oil but its an interesting read:

http://www.bdbatteries.com/hydrogenventing.php

Bruce

[Larwyn]

My battery venting "scheme" consists of a low mounted vent to allow intake air so the lighter than air hydrogen can float out the "overhead" vent without creating a vacuum. I briefly considered forced air ventilation of the battery compartment but decided against it. Convection seems sufficient and you probably do not want to know the cost and power requirements of "explosion proof" ventilation fans intended for use in a hydrogen environment. Computer fans do not come close to meeting the requirements.

[proformance]

Computer fans do not come close to meeting the requirements.

You have a good point regarding the computer fan. I neglected to cover this. I recommend only using brush-less fan motors.

[Shadow Catcher]

One thing to remember if you were to use a powered fan it would need to be on only when the batteries were actually being charged.
There are a number of sealed battery boxes with a small vent hose that meet NHRA standards i.e. http://batteries.batterymart.com/noco-d ... oLow--list
Realistically, if it is sealed and has a vent and no spark source how likely is there to be a problem.

[bohemian]

I looked at the sealed Aluminum boxes. and the first thing that came to mind is the vent tube is rather small.
Is that small vent all that is needed?
I decided to go with a 3" vent hole in the floor on the right side of the battery and 3" hole at the top of the enclosure on the left side of the battery.
Also I'm going with a AGM battery.
I think this would be a safe route to take.
Thanks everyone, Your information has been a great help.
Wayne

[Tumbleweed_Tex]

Dog and I were having this very same conversation last week, and he brought up some really interesting points.

In all the discussions and technical explanations we read, it seems to be an accepted fact that because hydrogen is much lighter than air, the hydrogen will rise. While this is true in the case of hydrogen contained in something like a balloon or a dirigible…Dog says the key is that it is contained, or separated from the air.

When hydrogen is released INTO the air, mixing occurs. If it didn’t occur, the released hydrogen and the oxygen in the air would never get together in a way to cause a fire or explosion. This means the “stuffâ€