Safety question about battery located under the bed

[bkahler]

I was browsing Fred's Airstream Archives (awesome site by the way!) looking for information about my 20' Argosy motorhome when I ran across this picture.

The battery in the picture is sitting right next to the generator compartment. The whole compartment in the picture is underneath the bed/couch. It's pretty obvious that there is no isolation, seal, or whatever you want to call it between that compartment and the inside of the coach.

What I'm wondering is just how safe is it to have a battery sitting in a location like that. I would think that when charging the battery is going to off gas possibly putting fumes inside the coach itself.

Is this a safe situation or am I over reacting? I'm looking for a new location for one of the batteries and this location would be ideal but the safety aspect really concerns me.

Any thoughts?

Thanks,

Brad

[wayneskid]

The coach/house batteries (2) in my Interstate are located under one of the beds. BUT, they are enclosed in a heavy metal, sealed battery box that is vented to the outside. I assume this is standard practice in cases where the battery(s) are in the living space.

Wayne

[idroba]

I am not sure anyone will say it is safe and without problems. Hydrogen gas is produced when batteries are charged and discharged, and, given the right conditions could build up and be ignited.

So, inherently a problem, but..... how much will never be able to be determined. I am sure lots and lots of batteries are placed like yours is now, and have worked without exploding..

So, although never a great situation, the actual danger is hard to tell. What risk are you willing to take? No one can decide that for you, nor should they.

[bkahler]

Originally Posted by wayneskid

The coach/house batteries (2) in my Interstate are located under one of the beds. BUT, they are enclosed in a heavy metal, sealed battery box that is vented to the outside. I assume this is standard practice in cases where the battery(s) are in the living space.

Wayne

Thanks Wayne. Your description pretty much confirms what I was thinking. It shouldn't be hard for me to get an enclosed battery box back there that I can vent to the outside. There is enough room I might be able to get two batteries back there. The Argosy 20' mh only came with one coach battery and two would be so much nicer.

Thanks,

Brad

[bkahler]

Originally Posted by idroba

I am not sure anyone will say it is safe and without problems. Hydrogen gas is produced when batteries are charged and discharged, and, given the right conditions could build up and be ignited.

So, inherently a problem, but..... how much will never be able to be determined. I am sure lots and lots of batteries are placed like yours is now, and have worked without exploding.

With my luck that's not necessarily guaranteed

So, although never a great situation, the actual danger is hard to tell. What risk are you willing to take? No one can decide that for you, nor should they.

When I can I prefer to minimize potential dangerous situations. Doesn't mean I haven't taken changes it just means I've been lucky so far

Luck won't last for ever so if I do place them back there I'll do something like Wayne describes above.

Thanks!

Brad

[92landyacht]

I wouldn't without a properly vented to the outside sealed battery case. Something about oxygen/hydrogen and an ignition source (Water pump motor and switch contacts) under my bed concerns me.

[ddruker]

In lead acid batteries, excessive charging electrolyzes some of the water, emitting hydrogen and oxygen. This process is known as "gassing". Wet cells have open vents to release any gas produced, and sealed batteries rely on valves fitted to each cell. Wet cells come with catalytic caps to recombine any emitted hydrogen. A sealed cell normally recombines any hydrogen and oxygen produced inside the cell, but malfunction or overheating may cause gas to build up. If this happens (for example, on overcharging) the valve vents the gas and normalizes the pressure, producing a characteristic acid smell. Valves can sometimes fail however, if dirt and debris accumulate, allowing pressure to build up.

If the accumulated hydrogen and oxygen within either a sealed or wet cell is ignited, an explosion can result. The force can burst the plastic casing or blow the top off the battery, spraying acid and casing shrapnel. An explosion in one cell may ignite the combustible gas mixture in remaining cells.

It is also possible for lead acid batteries to give off a small amount of hydrogen sulfide gas, which while probably not dangerous doesn't smell very nice.

The moral of the story is that it's a good idea to vent lead acid batteries to outside air. This all falls within the realm of relative risk - are you sure to die a horrible death if you put a lead acid battering in a sealed compartment with an ignition source nearby - nope. But you would be better off venting to the outside.

Also, because they have a lot of mass, it's also important to make sure batteries are securely attached to the trailer - or they can turn into an 80 pound missile that's also full of sulfuric acid...

[JamuJoe]

I can't see the full battery to determine type. A flooded lead acid battery would not be desirable in an interior compartment without sealing and effective external ventilation, due to the gassing during mentioned in #3. AGM batteries would be safer, but still should have exterior ventilation in case of accidental overcharging.

[bkahler]

Pretty much what I suspected, a sealed battery compartment is the only way to go. Buying or making a battery box is no problem, finding the right vent might make this more interesting. I wonder if venting into the generator compartment would be appropriate or if this would turn into a potential source of ignition somehow?

Thanks,

Brad

[wayneskid]

"There is enough room I might be able to get two batteries back there. The Argosy 20' mh only came with one coach battery and two would be so much nicer."

Brad, when you're shopping for a battery box, you might think about going to 6v batteries, some of which are a little taller than a similar 12v. For my van I replaced the original 2 84Ah 12v AGMs (parallel wired) with 2 120Ah 6v FLAs (series wired). This increased my capacity from 164 Ah to 240 Ah. See this post:http://www.airforums.com/forums/f240...ies-91911.html

[bkahler]

Originally Posted by wayneskid

"There is enough room I might be able to get two batteries back there. The Argosy 20' mh only came with one coach battery and two would be so much nicer."

Brad, when you're shopping for a battery box, you might think about going to 6v batteries, some of which are a little taller than a similar 12v. For my van I replaced the original 2 84Ah 12v AGMs (parallel wired) with 2 120Ah 6v FLAs (series wired). This increased my capacity from 164 Ah to 240 Ah. See this post:http://www.airforums.com/forums/f240...ies-91911.html

Wayne,

I'll look into the 6-volt possibilities. Do you happen to have any pictures of your battery box that you could post? I would also like to see a picture of the vent from the outside if you have the chance.

Thanks!

Brad

[DKB_SATX]

Originally Posted by bkahler

Pretty much what I suspected, a sealed battery compartment is the only way to go. Buying or making a battery box is no problem, finding the right vent might make this more interesting. I wonder if venting into the generator compartment would be appropriate or if this would turn into a potential source of ignition somehow?

Thanks,

Brad

Sealed lead-acid or AGM batteries are set up to have very little off-gassing. They're more expensive per amp-hour and I suspect their slightly longer lives don't balance the cost completely, but it would be a quick solution to your problem.

I use an AGM inside the trailer to run my CPAP via an inverter. Once it was all done I was probably close to the price of a 12v CPAP, but I already had 2 machines and the inverter has other potential uses, so I went that route. I chose an AGM so I wouldn't be worried about it being tipped over or off-gassing a bunch of hydrogen while being charged.

[wayneskid]

Brad,
Here's a pic of the batt box with the original 12v AGMs. Sorry it's dark and doesn't show the vent very well.


Here's another:

The vent is at the top in both pictures; it exits out toward the side of the van then down through the floor. The vent hose is 3" heavy vinyl flex hose; similar to dryer vent hose but heavier.

[bkahler]

Originally Posted by wayneskid

Brad,
Here's a pic of the batt box with the original 12v AGMs. Sorry it's dark and doesn't show the vent very well.
Attachment 170402

Here's another: Attachment 170403

The vent is at the top in both pictures; it exits out toward the side of the van then down through the floor. The vent hose is 3" heavy vinyl flex hose; similar to dryer vent hose but heavier.

Great! Thanks for the pictures. When you mentioned venting what immediately came to mind was a hole out the side of the shell, venting through the floor makes so much more sense. In my situation that would be easy for me to accomplish as well.

It shouldn't be difficult to fabricate an aluminum or steel box to hold one or two batteries. Dang, one more thing to add to the list

Thanks!

Brad

[idroba]

But hydrogen is lighter than air and will not vent down properly so floor venting is not going to work right.

[bkahler]

Originally Posted by idroba

But hydrogen is lighter than air and will not vent down properly so floor venting is not going to work right.

I wonder if anyone told Airstream that? If I'm not mistaken Wayne's installation was by Airstream.

That raises other questions then. Maybe the solution is to have an upper and lower vent to allow for better breathing.

[idroba]

All vintage AS trailers I have had used a vent tube which sloped upwards from the battery cap vent tube system located inside, as delivered from the factory, or they used a sealed from the inside battery box directly vented to the outside. My 310 motorhome had it's batteries in one of the exterior compartments, on the curved side, under the rig, and outside the living compartment. The box shown in the photos is one I have never seen, so can't comment on how it works.

[bkahler]

So what it boils down to is I need to make sure I have a vent that travels upwards to vent the hydrogen gases.

Do you recall what diameter the vent pipe is?

[dadstoy]

Yes, the vent must be higher then the battery.

[bkahler]

Ok, I think my plan will be as follows:

1) build or buy a sealed battery box that will fit the area next to the genset compartment
2) if one battery it will be 12v (duh!), if two batteries I'll use 6v
3) vent the box from the top or top edge into the genset compartment
4) live happily ever after

Thanks all!

Brad