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Can spray foam secure LFP batteries in a box?

1039 Views 9 Replies 7 Participants Last post by  jdege, 
J
Hi All, our last offshore race had 18 to 21 knot winds and very big seas, and we took on a lot of water. I decided my battery was not protected in it's plywood box, so I bought an IP67 rated box to put them in. Pictures below.

You can see there is space around the cells. The big space will be filled by a stained 2x4 that I will mount the BMS and terminals on. Cables will come into the box through IP68 wire glands.

I'm trying to figure out how to fill the smaller spaces on the other three sides. I'm thinking about spray foam. If you have tried spray foam for something like this, did it work? Is the spray foam conductive?

Other suggestions would be appreciated as well.

Thanks!


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R
Spray foam is also an insulator. I think that may be a bad thing to encapsulate them in foam. They might overheat. Not good for a battery. I would maybe make some shims out of some other material that doesn't create a completely sealed blanket.

I like your idea mechanically. That space looks about perfect for some 1/2 inch pink closed cell foamboard jammed in around the top. That might give you the same effect without encapsulating it completely. Allowing a little "breathing room".

This is just my opinion. I am not an expert on this topic. However, I do know that you need to use closed cell foam. The open cell (lighter/fluffier stuff) soaks up water.
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OntarioTheLake
Yeah, I'd use something else, maybe wood even before I'd use foam. Spray foam makes a mess, and is way more than what you need; just block the batteries in there.

What's with the skinny wiring? Are those direct-wired devices?
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J
OntarioTheLake said:
Yeah, I'd use something else, maybe wood even before I'd use foam. Spray foam makes a mess, and is way more than what you need; just block the batteries in there.

What's with the skinny wiring? Are those direct-wired devices?
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The skinny wiring are the voltage sense / balance leads.
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J
Others have said that the closed cell spray foam is an insulator as well. On the other hand, LFP batteries don't make much heat, and the BMS does have temp sense. But I do see the point. Maybe some wood strips.
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tempest
I might buy a few squares of interlocking drainage flooring squares and cut them to size. They would not insulate the box like foam.

Something like this --> NoTrax® Modular Lok-Tyle™ Drainage Mat Interlocking Tile 12" x 12" Black (globalindustrial.com)

It wouldn't be messy and you can remove them easily.
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J
tempest said:
I might buy a few squares of interlocking drainage flooring squares and cut them to size. They would not insulate the box like foam.

Something like this --> NoTrax® Modular Lok-Tyle™ Drainage Mat Interlocking Tile 12" x 12" Black (globalindustrial.com)

It wouldn't be messy and you can remove them easily.
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Love that suggestion, thanks! I can use those on top of the cells to fill to space above as well.
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marcjsmith
could you strap the batteries to the inside of the box. right to left across the top of the top of the batt between the terminals. down about half way and attach your straps to the inside of the box..
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paulk
As Marc suggests, ORC regulations call for batteries to be strapped down so they don't move, even if the boat pitchpoles. Wedging them in place with wood is not going to comply.
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jdege
The case itself will need to be strapped down...
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