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diy solar

Fire proof battery box?

I'm going to use one of these:
Truck Tool Box


Not sure how much I need it for LiFePO4 batteries, but I like the idea of using it.

I was going to mount the charge controller and inverter on the wall above it, but not I'm leaning toward spraying the inside of lid with some truck bed liner and just mounting the equipment to it. Then, remove the batteries, close the lid, and the whole thing is mobile... sorta.
 
Many people coming out in favor of fireproof boxes. I would bet 80%+ of builds have not done this. I did not use one and I won’t take one apart to make it fireproof.

It’s interesting to look at the “up in smoke” section of the forum to see how many of those containers were flammable vs non flammable containers and draw your own conclusions.

I feel if this already built, may not be worth the time to rebuild it. If it’s not built, if it’s not a cost or time restraint may be worth the effort.

I looked at cement board which some may find easy to work with, but not me. I also did not find fire retardant paint locally.

I used unpainted plywood for mounting most things except the batteries. For batteries I used spray painted the plywood.

I am mentioning this because a lot of these projects become both money pits and time pits and you need to draw the line somewhere.
 
Ampster said:
Don't forget about the need for some of that equipment to need air circulation for cooling.
Click to expand...
Right. I was only planning on closing the lid for transport, or when I want to leave it shut down and secured in the shed. The thing I like about this box is that it allows for opening and closing the lid while the back of the box is pushed up against the wall. A handy feature if I decide to bolt it down to the floor.
 
I lined my 2p16s battery with 1/2inch concrete board, here's a picture before the lid went over the cells. The lid is made of 3/4 plywood lined with 1/2 concrete board .
 

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I'm contemplating some of these same concerns. I'd like to build a central battery backup system for my home. The idea location is in my basement near the main 200A breaker panel. My basement is unfinished and as such has concrete floors and cinderblock walls so the main vulunrability to a fire is the wooden floor joists above. My current thinking is to build a small room with steel studs and fire rated drywall and a steel door. The room will have a layer of ceramic fiber insulation on all sides (except the floor). This is the same insulation that is used to line kilns and forges and can withstand up to 2300 degrees F. The room would be just big enough for a server rack and the inverter. Outsie the room would be all the AC conduits and subpanel for my backed-up circuits. Obviously, I would need to ensure there's ventilation in the room to avoid it getting to warm during charging but the basement already stays pretty cool (but above freezing) year round.

Thoughts?
-Matt
 
armstrom said:
Thoughts?
Click to expand...
If you are using LFP batteries I would spend resources on a robust battery management system with temperature sensors that would trigger the BMS to disconnect the pack from any loads or charging sources. That would be more cost effective than trying to construct a fireproof room.
It is always a good idea to cover floor joists with 5/8 inch drywall to provide a one hour rating to that ceiling regardless of whether you have batteries there. Electrical fires from overloaded circuits are the typical risks. Smoke and heat detectors would also warn the occupants of a fire from any source.
If you are using LFP, research will tell you that the risk of LFP is significantly less than other Lithium chemistries.
 
Drywall is cheap. Several inches would be my choice. And some way to vent the smoke?

There is a limited amount of fuel for a LiFePo4 fire. Would need some calculation.
 
Ampster said:
If you are using LFP batteries I would spend resources on a robust battery management system with temperature sensors that would trigger the BMS to disconnect the pack from any loads or charging sources. That would be more cost effective than trying to construct a fireproof room.
It is always a good idea to cover floor joists with 5/8 inch drywall to provide a one hour rating to that ceiling regardless of whether you have batteries there. Electrical fires from overloaded circuits are the typical risks. Smoke and heat detectors would also warn the occupants of a fire from any source.
If you are using LFP, research will tell you that the risk of LFP is significantly less than other Lithium chemistries.
Click to expand...
Yeah, I actually have about 20kWh of brand new 18650 cells that I decided against using due to fire hazard with regular lithium ion cells. LFP does seem much safer but yet I still see reports of fires on this forum. Regarding just covering floor joists with drywall, that's actually very tough to do in a basement while keeping the house code compliant. Unless a basement is already finished most of the time there are a lot of junction boxes and plumbing disconnects simply mounted to the joists. It is against code to enclose those boxes behind drywall. That's why you see so many people install drop ceilings when they finish a basement, it allows you to keep all your existing wiring and plumbing as-is since it's all still accessible by just lifting up the ceiling panel. I'll continue to weigh my options. Thanks for the feedback!
-Matt
 
I used a 16 ga. Electrical cabinet lined with 1/4 inch cement board covered with 1/16 inch silicone sheet. I can sleep well with it under the bed.
 

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I am a Professional fire man for 20+ years.

Do not put batteries in a metal enclosure. Use drywall. that is what is used for firewall and fire protection in gun safes. When a battery overheats, we get H2 production. THat needs to be oxidized pronto, molecules at a time! When a cabinet full of it decides to deflarate... ya, know.

so, ventilation, and heat dissipation. cement board is not your friend. drywall will be a fire barrier, but not for an interior source like a big battery.

I am new to the big battery world, but I do know what I am paid to do.
 
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