Securing batteries under bed

[Paprika]

Like a number of Airstream owners, I've upgraded my 27FB's electrical system to include batteries mounted under the front bed. What I haven't figured out is a good way to secure them.

The two batteries weigh 73 pounds apiece. The bed doesn't seem sturdy enough to be used as a basis for straps or brackets, and putting a few screws into the thin plywood floor doesn't sound very robust.

Ideally, I'd put threaded rods all the way through the floor to the underside of the rig, and use those to secure a hold-down bar across the tops of the batteries. But I'm nervous about drilling through the floor, since I don't know what's in there.

How have other owners solved this problem? Having a hundred fifty pounds of batteries restrained by nothing more than a plywood box that keeps them from sliding around, which is my current setup, isn't a good solution. I need to strap them down securely somehow.

Suggestions?

[TheGreatleys]

Originally Posted by Paprika

Like a number of Airstream owners, I've upgraded my 27FB's electrical system to include batteries mounted under the front bed. What I haven't figured out is a good way to secure them.

The two batteries weigh 73 pounds apiece. The bed doesn't seem sturdy enough to be used as a basis for straps or brackets, and putting a few screws into the thin plywood floor doesn't sound very robust.

Ideally, I'd put threaded rods all the way through the floor to the underside of the rig, and use those to secure a hold-down bar across the tops of the batteries. But I'm nervous about drilling through the floor, since I don't know what's in there.

How have other owners solved this problem? Having a hundred fifty pounds of batteries restrained by nothing more than a plywood box that keeps them from sliding around, which is my current setup, isn't a good solution. I need to strap them down securely somehow.

Suggestions?

I suggest purchasing battery trays that match the form factor of your batteries and screwing the trays to the floor.

https://www.amazon.com/gp/aw/s/ref=is_s?k=battery+tray

[prairieschooner]

& covering at least the Positive Terminals.

[Paprika]

Thanks for the suggestions! The battery tray idea is a good one, but I can't find any that would fit. These are Victron 160 Ah 12 V LiFePO4 batteries, and they're 12.5” x 9” x 13.2” high. That's wider and taller than a group 31XT, and I have yet to find a tray that will fit.

As for covering the battery terminals--I generally do, but these batteries are covered by a wooden lid (not shown) as well as the bed platform itself. However, I've ordered a set of PVC terminal covers and will see whether I can get them to fit over the large, metric terminals. There's always the dropped-wrench scenario to worry about, so better safe than sorry.

Meanwhile, I'm still looking for ways to secure these batteries. Any other ideas?

[perryg114]

The box you have is plenty sturdy. Just put some sort of foam padding in there to take up the space to keep them from shifting. Not sure if the batteries out gas and what the failure mode is if one shorts. Are fumes flammable or toxic. Is there a way for them to vent outside. I have seen lead acid batteries explode before and it is pretty common for out gassed Hydrogen to cause an explosion hazard.



https://www.ntsb.gov/news/events/Doc...1d-Doughty.pdf


https://en.wikipedia.org/wiki/Lithiu...sphate_battery


Perry

[eganwh]

I utilized the existing battery tray from the front box and screwed a piece of aluminum angle to hold the tray against the back bed frame wall. Also used a piece of aluminum square tubing to divide the batteries. Realizing no battery tray exactly fits your bats, you could use multiple angle brackets on several sides screwed to the floor, or build a base from plywood to match the battery outline.

My bed frame is fairly secure, so I drilled holes on both sides of the center lower bed frame and used a strap with S-hooks through the holes to hold down the batteries. The bats seem really secure with this setup, but I have not road tested yet.

Blog here: http://www.airforums.com/forums/blog...shing-up-2972/

Originally Posted by Paprika

Meanwhile, I'm still looking for ways to secure these batteries. Any other ideas?

[Paprika]

Thanks for the links, Perry. The Doughty white paper refers to lithium polymer batteries, which are vulnerable to thermal runaway, among other failure modes. Lithium iron phosphate (LiFePO4) batteries used in RVs like mine have a different chemical makeup and as far as I can determine, have no fire problems. And unlike lead-acid batteries, neither lithium battery type emits any gasses.

I already have the batteries blocked in place by wooden spacers, so shifting is not a concern in normal circumstances. I want to secure them against vertical motion, such as might occur on rough roads or in an accident.

[Pencilpusher]

I recently moved 3 Battle Born lithium batteries under the bed of my 27 FB. I built a new tray by taking 1/2" plywood to put on top of the floor. I then cut 1" X 2" strips to mold around where the batteries would sit on the tray. I then glued the 1x2 strips to the plywood and further secured them by using wood screws into the 1 x2's from underneath the piece of 1/2 " plywood.

I then used long strips of Velcro attached by wood screws to the 1x2's to run across the batteries. They seem very secure to me and I do not foresee a problem.

Eric

[Hicks3456]

Originally Posted by perryg114

The box you have is plenty sturdy. Just put some sort of foam padding in there to take up the space to keep them from shifting. Not sure if the batteries out gas and what the failure mode is if one shorts. Are fumes flammable or toxic. Is there a way for them to vent outside. I have seen lead acid batteries explode before and it is pretty common for out gassed Hydrogen to cause an explosion hazard.



https://www.ntsb.gov/news/events/Doc...1d-Doughty.pdf


https://en.wikipedia.org/wiki/Lithiu...sphate_battery


Perry

I agree - batteries can catch fire - I certainly would not want them under my bed

[Life is a Highway]

With respect this seems a accident waiting to happen.

I do not understand why someone wants sulfuric acid batteries that when charged vent fumes into a living area? Or can leak.

Any of us whom have seen a battery explode can relate. Terminal ends exposed to any possible metal causing a short.

They should be in spill proof battery boxes and vented to outside air

Safer to relocate outside in my humble opinion.Although I get it with the wants and needs for boondock electric power

Be safe!
Merry Christmas All

[75Bob]

I not only moved my battery from the rear to the front (behind the propane tanks), but also added a battery in parallel on the inside in the front under the dinning seat. When I had it installed I was told that it was a LAW that any interior batteries be Vented! I believe that you are playing with fire and should stop, and get more info about this before you continue. Please check this out further.

[Paprika]

"batteries can catch fire - I certainly would not want them under my bed"

As I explained, LiFePO4 batteries don't catch fire, spill, or emit gases. Yes, if the terminals were shorted together by a wrench, you'd have a dangerous situation with any battery type. But with the batteries properly secured and covered - which is the topic of this thread - that isn't going to happen.

Moving the batteries inside has many advantages: it reduces tongue weight, protects batteries from freezing temperatures, and shortens cables, reducing voltage drop. It also allows the use of larger batteries than will fit in the standard tongue-mounted battery box. For these reasons, it's pretty much standard practice in upgrades that use AGM or LiFePO4 batteries, which don't require venting.

"I do not understand why someone wants sulfuric acid batteries that when charged vent fumes into a living area?"

I appreciate your concern for my safety, but it's misplaced. We are not talking about flooded-cell lead-acid batteries here. Mounting AGM or LiFePO4 batteries under the bed or in other interior spaces is accepted and safe practice, and there is no law against it. Talk to the respected installers AM Solar or Rivet Master "Lewster" in these forums if you have any doubts on that score.

[paul10r]

If you are using Lithium batteries, it is true that they do not off gas and can be safely placed in a non-vented location, although for me personally, I am not too excited to have batteries of any kind directly beneath my bed.

AGM batteries are a different matter (http://rvnerds.com/2017/11/01/electr...-need-venting/).

[Life is a Highway]

Point well taken, My reading has the jury still out on venting etc.

This is from the solar industry in homes. Technology is advancing very fast, Im waiting for the RV version a all in one suitcase battery pack like a Tesla’s battery wall.

Those batteries are still in a trailer bouncing down the road. Like you idea of securing and covering them terminals.

As you mentioned if your spouse or you or a repair tech or a playing grandchild drops a metal conductor - anything across those exposed terminals you can quickly become the classic "BY THE POWER OF HE MAN” as it melts and burns even if it might not blow up.

Ask the young inexperienced tech who's gold wedding ring touching a chrome wrench that hit the positive starter nut and vehicle frame. Found out pretty quick Gold melts rather quickly into the skin. How would I know that?

Nuff said.

[waninae39]

This is what i did and works fine

1/4" ply with 1/2 wood strips glues around the edge of the base of the battery- these prevent the battery from sliding
i then use std metal ac strapping . this is bent over the battery to form the shape and screwed to the 1/4 plywood- this prevents the battery from tipping- only need on the long side

i then screw the plywood under the bed.

Each winter, i undo one screw and lift the LiON batteries out for winter storage