Dual Battery Venting

[vanhack]

Hi folks, my first post here.

I am in the process of installing a dual battery system, I have chosen a Optima yellow top, which is classed as a Spill proof AGM sealed battery. Optima themselves recommend that the battery be vented to the outside. Reading the interweb, one can see recommendations from the boat community that it produces hydrogen when over charged, which only occur if the DBS failed. The battery would or should have a pressure relief valve for the hydrogen gas to release into the atmosphere.

BUT I don't see many people providing vents for their battery boxes if placed in the cargo/trunk area...just wondering if anyone has come across this.

My battery may reside in the engine bay, If I can move a couple of things around, or under the chassis if enough protection can be fabricated, I did consider the cargo area next to the fridge and power all my aux requirements in the rear of the patrol, but am scared that a vent can not be made for hydrogen to escape to outside the cab.

 

[Joe917]

Many here will argue AGMs do not need to be vented.
Here is a good explanation of how to correctly vent a battery box: http://www.bdbatteries.com/hydrogenventing.php
I would follow the battery manufacturer's directions, not anecdotal forum advice.

 

[dwh]

This has been covered a few times in the 12v section of this forum.

Sealed lead-acid batteries (such as AGM) only vent when overcharged.

If your DBS failed (with the solenoid engaged) and left the aux battery tied to the engine battery full-time - driving around like that will no more overcharge your aux battery than it would overcharge your engine battery.

Boats are different. They might run their engines non-stop for days on end. That could end up overcharging and forcing the battery to vent. The mostly likely scenario though would be failure of a shore power charger on a boat that is connected to shore power for weeks or months at a time. So on a boat - yea, always vent the battery space. Also, always vent the engine space. Also, always vent the bilge. Also, always....meh...boats...

But even if you did actually overcharge the battery and force it to vent - it won't vent much and not all that fast. Hydrogen buildup takes a while to become dangerous. Find a way to run a 1" vent to the outside and it'll be fine in the one in a million chance that the battery actually vents. Make sure you vent from the top of the space, as hydrogen rises, unlike propane which sinks and needs a vent at the bottom of the space.

Battery manufactures are corporations and corporations phear the lawsuitz and recommend that you never do anything which might put your eye out. You should always wear safety glasses when operating a BB gun.

 

[Paul B.]

This has been covered a few times in the 12v section of this forum

Where exactly is that? I took a quick look, couldn't find it. It's easy to get lost in here reading all the cool info.

 

[Ducky's Dad]

The house battery on my truck has been mounted under the cab on the frame rail for close to ten years. First one was an Optima, then replaced with an Odyssey. Never a lick of trouble with the mounting location, but I did fabricate a HD battery box/mount out of welded steel to protect the battery from impacts. Putting in a second house battery right now, next to the old one. Have two Optima Blue dual purpose batteries going in there, maybe even this week. I can't see a good reason to give up interior space to batteries if you have alternatives.

 

[rayra]

Optimas are 100% sealed and can be mounted in any orientation. Not that venting is a concern of any significance with a 'sealed' battery anyway. Besides, if your concern is flammable gases, the last thing you want to do is concentrate them in a sealed box.

 

[rayra]

Many here will argue AGMs do not need to be vented.
Here is a good explanation of how to correctly vent a battery box: http://www.bdbatteries.com/hydrogenventing.php
I would follow the battery manufacturer's directions, not anecdotal forum advice.

Speaking of "anecdotal forum advice" -

http://www.optimabatteries.com/en-us/technology/agm-batteries

" Sealed AGM batteries do not sulfate or degrade like flooded batteries do, since they are not vented to the atmosphere. [emphasis added]"

http://www.optimabatteries.com/en-us/products/yellowtop

"Spillproof, mountable in virtually any position"

 

[vanhack]

Actually, spillproof yes, but they do create hydrogen when over charged, but only if over charged. If you see their website, it does say to provide ventilation.