Building a Battery Tray

[expozen]

I need a proper place to secure my new battery bank. The locker I want to build in has been painted. My plan is to remove as much paint off the inside of the hull as I can by using a wire wheel attached to a drill, then use AquaStrip, then probably some more wire wheel, then clean with acetone, then sand a little with 50 grit for tooth, then clean with acetone. I've attached a drawing of what I'm thinking of building. Any tips or recommendations would be much appreciated. It's my first time building something like this on my boat, and I'd like it to go smoother than some of the other things I've attempted recently.

[coopec43]

Why not make a f/g tray ?

Or buy one?

https://www.ebay.com.au/sch/i.html?_...+tray&_sacat=0

[stormalong]

1) Don't use aluminum, as copec43 said use fiberglass. Aluminum will corrode badly from battery acid fumes. But do not use an open tray - See #3.

2) Don't raise the bottom of the tray any higher than is necessary for the fiberglass buildup. You may want taller batteries in the future.

3) Make it liquid tight to a height over the batteries. This is to contain the acid if a battery springs a leak.

4) Plan in some ventilation on the top so that hydrogen gas has a place to go. You do not want it captured in the battery box.

[expozen]

Originally Posted by stormalong

1) Don't use aluminum, as copec43 said use fiberglass. Aluminum will corrode badly from battery acid fumes. But do not use an open tray - See #3.

2) Don't raise the bottom of the tray any higher than is necessary for the fiberglass buildup. You may want taller batteries in the future.

3) Make it liquid tight to a height over the batteries. This is to contain the acid if a battery springs a leak.

4) Plan in some ventilation on the top so that hydrogen gas has a place to go. You do not want it captured in the battery box.

It's an LFP bank. Sorry I didn't state that. I was more concerned about the structural details. Like would the tray distribute the weight of the batteries over enough area of the hull? Does it even need fiberglass tabbing, or would filleting alone be sufficient. Or maybe it should have more layers of fiberglass for tabbing? Would it be easier to first bed the stringers (is that what they would be called here?) in 5200 rather than thickened epoxy?

[Boatyarddog]

Originally Posted by expozen

It's an LFP bank. Sorry I didn't state that. I was more concerned about the structural details. Like would the tray distribute the weight of the batteries over enough area of the hull? Does it even need fiberglass tabbing, or would filleting alone be sufficient. Or maybe it should have more layers of fiberglass for tabbing? Would it be easier to first bed the stringers (is that what they would be called here?) in 5200 rather than thickened epoxy?

I built mine in a locker.
4 T-105 Trojan 6 vt. cells(about 250lbs)
I had to cut the pieces of 3/4" plywood first and fit them together outside the locker, as the opening was to small to assemble and place in the area.
I then glassed all pieces inside and out with mat.
Be sure to coat the wood with thinned resin( I used poly resin), before glassing.
After coating and glassing, I then sanded all surfaces with 50 grit for "tooth", but just the area needed to glass over the seams and tabbing to the Hull and wall.

Then began assembling in the locker with SS Wood screws, and glassed over the seams on the outside of the box, the supports to the floor and Hull, and any area that would not be accessible once the tabbing, (YES, TO TABBING), you don't want this to be sliding around.
After assembling in the locker and glassing to the Hull,I then finished the interior of the locker with glass at the seams.
Coat it all with resin and it's finished!
Do be sure to vent the area to the outside, I placed a top on half of the locker and made the other half mobile so you can seal the top and remove as nessessary
Takes a little time but it's a custom project, very sturdy.
Cheers,
SV Cloud Duster

[guyrj33]

I made a battery box for 2 6v GC batteries using 1/4" plywood, bi-ax glass and epoxy resin. Box includes a shelf for a 400 map fuse and holder, also shunt.
I'm sure it's more than strong enough.

Is a conductive battery box a good idea? I can imagine some bad things happening.
I can also think of some times when it would be nice to have Li batteries contained in a flameproof box.

Is epoxy resin more flame resistant than polyester resin? I know epoxy is stringer and i've seen polyester resin burn, it's scary.

[wayne.b]

Originally Posted by expozen

It's an LFP bank. Sorry I didn't state that. I was more concerned about the structural details. Like would the tray distribute the weight of the batteries over enough area of the hull? Does it even need fiberglass tabbing, or would filleting alone be sufficient. Or maybe it should have more layers of fiberglass for tabbing? Would it be easier to first bed the stringers (is that what they would be called here?) in 5200 rather than thickened epoxy?

===


The panels absolutely have to be tabbed. Filleting has little or no structural strength by itself. This is a critical assembly for a number of reasons so I'd suggest getting some professional help who is experienced with building structural fiberglass components.

[expozen]

Sounds like I should beef it up! I made a few changes and attached as pdf drawing. Wish me luck! And thanks for all the help!

[slowpoker]

After you finish whatever battery box you made, buy a remnant of shower and tub vinyl liner sheet sold at Home Depot or Lowes where they keep the bathtubs, etc. and in one piece, without cutting, fold and fit it inside as to line the full inside , even up the sides.
It is a gray color, thick, flexible and durable sheet of vinyl that is impervious to acids, water, fumes, even UV resistance and will not crack or tear or puncture to retain and protect the inside of the battery box. Easy to clean and remove also.
You can use the leftover material of that gray vinyl shower pan liner to cover the batteries connections and wiring because it is an excellent isolating material, leaving spaces for the Hydrogen gasses to be vented where required.
It cuts and folds easily to fit anywhere and can even be used to make gaskets or isolating material for electrical stuff or a vibration absorbing chafe protector, a perfect mast boot, non-slip galley counter protector, rain and sun covers for equipment in the cockpit, rain catcher, a foredeck protector when anchoring, it has a million uses. Not expensive for the left over remnants. Slowpoker.