Safety question about battery located under the bed

[DKB_SATX]

Remember that the original batteries in wayneskid's Interstate were AGMs. Airstream may have chosen those because it was challenging to seal/vent the battery box well enough for cheaper flooded-cell batteries.

[idroba]

Originally Posted by 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

3.5) some vent holes at the bottom of the new battery box so air can get in.

Otherwise, excellent plan.

[Wazbro]

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

This is stated wrong, I checked the specs for the batteries you used and they are each 6V 240AH in series for 12V 240AH.

[bkahler]

Originally Posted by idroba

3.5) some vent holes at the bottom of the new battery box so air can get in.

Otherwise, excellent plan.

That I can do

[wayneskid]

Originally Posted by Wazbro

This is stated wrong, I checked the specs for the batteries you used and they are each 6V 240AH in series for 12V 240AH.

Nice catch You are correct; the new 6v batts are 240Ah each (20 hour rating); wired in series gives 12v/240Ah. My bad

Thanks,
Wayne

[ddruker]

You asked about the size of the vent - it does not need to be very large. 1/4" or 3/8" inside diameter tubing should be plenty big enough. You are not talking a high volume of gas being generated at one time.

[Chuckles]

In all honesty if you have batteries in the living quarters, Gell is the only way to go. However the charging system must match the Gell battery charge rates.

All other types will need venting not only from the battery vent but the compartment as well, hence why most battery locations are outside.

I made up a battery tray to the chassis, so it is open, but at the same time has some insulation around them for freezing conditions.

[Protagonist]

Originally Posted by idroba

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.

To help you manage the risk… Lower explosive limit for hydrogen gas is 4%; upper explosive limit is 75%, according to Material Safety Data Sheets (MSDS) for hydrogen, as published by AirGas, Air Liquide, and other companies that produce hydrogen commercially.

So, if the concentration of hydrogen in the air is less than 4% of the total volume of air, it won't ignite. In more practical terms, for every 100 cubic feet of interior volume in your Airstream, you would need 4 cubic feet of hydrogen gas for it to ignite. Most batteries, even traditional wet-cells, won't offgas that much hydrogen.

There is a bigger risk in a sealed but unvented battery box, because it's a much smaller volume, and you only need 4% hydrogen in the box to make it ignite if there's a spark or it gets too hot. So, if the battery box is not vented properly, you could turn the battery box into a bomb; but you wouldn't turn your whole Airstream into a bomb.

Still better to go with AGM batteries, though. Even if your Airstream won't explode, hydrogen gas is still classed as an asphyxiant; it will not do your lungs any favors if you breathe the stuff, even in small concentrations.

With regard to venting, the vent hole in the top need not be large, but needs to be at the very top of the box, and the vent hose should not dip or level out at all; it should go up all the way from the box end to the open end. You don't want the vent hose to trap hydrogen, either. The vent holes at the bottom should be larger than the vent holes at the top, or there should be more of them. In addition to allowing air in to replace the off-gassed hydrogen, they serve as drains for condensation.

[crazeevw]

Brad,
Check out this DIY Network YouTube video series. Somewhere there are instructions as to how the installed the 12V coach battery underneath the bed, and vented it outside as well.
Honestly, I started at video #1-01 and watched all the way through, very interesteing to be honest.
Good luck, Derek

Airstream Restoration - 01-1 Introduction - YouTube

[bkahler]

Derek,

Interesting restoration series, although I don't know that I would call it "restoration" it's more like a sprucing up than anything. Leaving behind the old carpet under the bed just seems tacky to me

The battery video isn't bad although I take exception to the fact that they used a cheap white plastic louver on the outside of the nice aluminum shell. Also they will have mud daubers inside the trailer in no time since they didn't put a screen over the opening. Mud daubers will fly in that opening, into the battery box and out the openings in the battery box into the under bed area. Not fun

Here's the battery installation video.

Airstream Restore DIY 09-4 Batteries - YouTube

Thanks for pointing this series out to me, I'll have to start watching them in my spare time.

Brad

[idroba]

It is a nice battery box. If anyone ever finds a source for it, I would like to know.

[bkahler]

Originally Posted by idroba

It is a nice battery box. If anyone ever finds a source for it, I would like to know.

I believe this is the box. Still haven't found the vent hose kit but I'm sure it's out there somewhere. It is 14-1/2" tall. Now I need to measure the compartment under the couch/bed and see if it will fit.

Dual GC2 battery box

Brad

[Protagonist]

Originally Posted by bkahler

I believe this is the box. Still haven't found the vent hose kit but I'm sure it's out there somewhere. It is 14-1/2" tall. Now I need to measure the compartment under the couch/bed and see if it will fit.

Dual GC2 battery box

Brad

Looks like the one in the video, all right. Another possibility might be Battery Boxes from BD Batteries

Looks like they used a QuickCable "QuickBox" brand vent kit, or similar. Actually two kits, one for the inlet, one for the exhaust. The QuickBox kit can be found at Quick Cable: Battery Box Vent Kit. It's worth checking out the "how-to" video at the web site, even if you buy a kit from sonewhere else. It shows more of the nuts-and-bolts end of the installation than the Airstream restoration video does.

[mefly2]

IIRC hydrogen sulfide gas is given off when charging batteries ... in your respiratory system - remember those HS chem classes years ago - the hydrogen sulfide recombines with oxygen, O2, + water, H2O, and forms weak sulfuric acid, H2SO4 (or, outdoors - acid rain). Stay away from those fumes ... they are corrosive to metal and very bad for the lungs in any concentration. AGM for inside batt locations.

[idroba]

Thanks for the help on locating the battery box. Much appreciated.

[Protagonist]

Originally Posted by mefly2

IIRC hydrogen sulfide gas is given off when charging batteries ... in your respiratory system - remember those HS chem classes years ago - the hydrogen sulfide recombines with oxygen, O2, + water, H2O, and forms weak sulfuric acid, H2SO4 (or, outdoors - acid rain). Stay away from those fumes ... they are corrosive to metal and very bad for the lungs in any concentration. AGM for inside batt locations.

Off-gassing is why battery boxes are vented to outside, and sealed otherwise. You're not the first to point out that AGM is preferable for batteries located inside the living quarters; we're all pretty much in agreement on that score.

When charging wet-cell batteries, if you're charging a good battery it releases hydrogen gas. If you're charging a bad battery (damaged plates, or low on electrolyte) it can release hydrogen sulfide gas. Neither gas is good to breathe.

[bkahler]

Originally Posted by Protagonist

Off-gassing is why battery boxes are vented to outside, and sealed otherwise. You're not the first to point out that AGM is preferable for batteries located inside the living quarters; we're all pretty much in agreement on that score.

When charging wet-cell batteries, if you're charging a good battery it releases hydrogen gas. If you're charging a bad battery (damaged plates, or low on electrolyte) it can release hydrogen sulfide gas. Neither gas is good to breathe.

I may or may not be deviating from why I originally started this thread but should I decide to switch to AGM batteries how does a person decide what size to get? Previously for our 310 we just bought two 12 volt deep cycle batteries and called it good and never really paid attention to what amp rating they were. Of course the last time I bought batteries like that was while sitting in a Wal-Mart parking lot with dead batteries

So for a small 20' Argosy motorhome what size AGM battery(s) would be appropriate? I'd like two batteries but am not yet convinced I can fit two in the space. I might have the space available question answered this weekend.

Thanks,

Brad

[92landyacht]

My general rule for coach batteries is to get the largest amp/hr battery I can fit/afford. More really is better in this case. More Amp/Hr means more run time. I hate to run out of juice.

[K4TCJ]

A few notes on installing batteries,
1. All lead acid batteries give off both gas AND heat, do not seal them in boxes where they hold the charging heat.
2. In our marine installations we ONLY use AGM batteries from LifeLine. These have proven over the years to be by far the best battery available at any price. No they are not cheap but installed and charged right we are getting 6 years plus service, sometime up to 10 years.
There are many ways to do any job, each installation will be different.
We also use the AGM batteries from emergency communication set ups where the batteries may sit for 6 months or more between charges.
Hope this helps......

[Protagonist]

Originally Posted by K4TCJ

1. All lead acid batteries give off both gas AND heat, do not seal them in boxes where they hold the charging heat.

All battery boxes should be vented to the outside of your unit, and be large enough to allow at least an inch of air space all around each battery. A vented box is not sealed and will not trap heat or fumes.

They should only be "sealed" to the extent that there's a gasket around the lid to make sure all fumes go outside through the vent, and not inside around the edges of the lid.