Fire Proof Containment

The Kilowatt Challenge

The Kilowatt Challenge

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Nov 20, 2019
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It's great to see the hive mind in action in here, as a community we're collectively pioneering this hobby and making it safer every day.

I'm wondering where we're up to with fire safety, specifically fire proof cabinets, enclosures, containers etc for our battery packs. Is there a common direction that we seem to be heading in or is anybody documenting / trailblazing some experiments around this topic?

Cheers everyone

Darren @TheKilowattChallenge
 
And I do both. I have it in an outdoor shed that is insulated. Then the batteries are stored in a filing cabinet. The metal enclosure keeps the battery isolated and contained. It's is not sealed and has vents. The idea is to make sure the batteries do not ejecct of it and to contain the fire. I'm sure my shed will be burning as well. I thought about having a sprinkler head over the shed roof as well and since it's outdoors I would make sure the pipes are filled with air until it reaches the inside so the water doesn't freeze during the winters. Again the sprinklers are there only to contain the fire and not to extinguish the fire.
 
Yeah I absolutely hear what you're both saying regarding storing them outside and I'm considering doing the same. Living in Sweden I have the cold weather sub zero charging problem to consider which I'll do a series on videos on I'm sure but I'm really curious if anyone has come up a good solution for a larger battery array and how to mitigate the fire risks. I agree Mike and there's a few discussion around the venting the poisonous gasses emitted during combustion and how to vent them in the worst case as well. I've seen some smaller solutions using insulation, fireproof plaster board, 2mm+ steel etc and they all look good but without "data" behind the designs, I'm still looking for something to really start getting my teeth into.
I'll be building 2 x 14s200p to start with so there's quite a few cells in there and it will take up quite a lot of space no doubt. I'm wondering what industrial solutions there are and if anybody is pursuing that?
 
Here's a good read on an incident involving a battery fire. The one thing to note in the pdf report is on page 33. As long as the flames are contained, all you have left is to contain the thermal runaway. It was surprising to see the two racks besides it were untouched. I've also seen some videos on how a tesla powerpack was tested with a thermal runaway.

Equipment failure at McMicken Battery Facility

An investigation with APS, first-responder representatives and third-party engineering and safety experts is underway into April 19 equipment failure at McMicken battery facility in Surprise.
www.aps.com www.aps.com

 
Yeah that's a really interesting report. You're right about the cabinets either side, that's fascinating and we can all learn from that. It's interesting to read that they concluded that the thermal runaway traveled vertically only because of the containment and that the gasses didn't burn because the was no open flame. I'll take a proper look at that on a PC screen rather than on my phone.
 
It's 2020 and they have to send someone out to verify a fire?
What's the cost of a camera onsite? vs 43 minute delay to confirmation.
Even if it is not online all the time.
They already have a connection for monitoring.

I guess firemen though it was safe after 3 hrs to open the doors :(
I probably would have though so too if the flames were out.

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Hello!

In my opinion it is essential to choose the cells someone uses, carefully.

I do not use 0 V cells, damaged, or low voltage cells.
Also drawing high current from used cells I dont.
All my cells have a fuse and the packs will shut down if temperature goes to high.

It is unlikly to have a fire then. But as precaution the packs are stored in a fireproof insulated cabinet.

I cannot store my packs outside the house, but I feel confident no fire will happen.

Sometimes you find people who do not have any idea what they are doing. Knowledge is power and avoids accidents.

Brgds
 
Rumburak said:
Hello!

In my opinion it is essential to choose the cells someone uses, carefully.

I do not use 0 V cells, damaged, or low voltage cells.
Also drawing high current from used cells I dont.
All my cells have a fuse and the packs will shut down if temperature goes to high.

It is unlikly to have a fire then. But as precaution the packs are stored in a fireproof insulated cabinet.

I cannot store my packs outside the house, but I feel confident no fire will happen.

Sometimes you find people who do not have any idea what they are doing. Knowledge is power and avoids accidents.

Brgds
Click to expand...
Like you - I don't have a reasonable option to have my battery bank out from under the house - and there are 8000 cells and counting. I do think about fire - and the battery bank is in a 'fire resistant' alcove. Its cinder blocks on the wall, concrete at the floor, and corrugated metal on top.. but... it's open on the side pointing out to a metal desk / computer area. If a fireworks type fire started - it would surely catch the house on fire.

On the other hand the battery bank...
- operates between 4.0v hi and 3.5v low - modest
- charges / discharges in the 100-300ma range - modest
- lives in an ambient temp of 50F/10C low and 75F/24C hi - modest
- never gets warm, no measurable heat in the cells - good
- is BMS'ed by Batrium w/shunt-trip - excellent
- is not showing any balance issues or loss of capacity issues - good.

For now, after 2 years of daily operation, I'm confident the cells will remain 'safe' as long as the continue to be controlled / used in a modest way. However....

Down the road, after 6,000? cycles and the batteries are down to 70% or 60% original capacity... I have no idea what the risks might be. Maybe the cells will start diverging, some turn in to heaters,... but hopefully Batrium monitoring will show pack degredation and aggressive maintenance will mitigate this. Time will tell :)
 
Hello!

Actually very cost efficient:

Thin Metal cabinet, with Rock Wool and Fire Resistant Drywall on the inside. Rock Wool is good against 1000°C ( ~1830F).
Both combined will prevent a fire from exiting the storage.

I also plan to add a pressure release on the top, maybe with a metal chimney pipe.

So far my ( not my original idea) is better then the governmental regulations for such batteries here in Germany.

Sandwiched it would be Iron/steel wall ; Rock-Wool ; Dry Wall (Quality F90 (Glas-Fiber) in Germany means safe for 90 min against Fire 1000°C).



Cheers

Christoph
 
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I have my Chevy volt batteries inside the house. It’s bothered me since I installed them there. I stay away from max charge, follow c-rates, and use a bms to monitor disconnect charge and load. Balancing isn’t needed yet. Cells are perfectly balanced. These things made me atleast able to sleep at night. But still didn’t feel safe. I was going to build this box inside but then I’d still have to worry about poisonous gases if there ever was a fire. Also insurance companies could give me a hard time if the batteries actually started the fire. So I had to move them outside.

This is what I came up with. To make the 3ft long x 2ft wide x 1ft deep box I used a 4x10 sheet of metal used for hvac. I bent it by hand. It is to thick for my aluminum break. Had metal studs laying around to strengthen up the walls and bottom of the box. I actually bent the main duct for my central heat and air the same way so this was easy. Atm it will hold 12.4kwh of chevy volt. I made it big enough to hold 2 more batteries, so it can hold 18.6kwh. The insulation is fireproof up to 2600 degrees. It’s used in kilns and in my wood boiler. This stuff really is fireproof. But for my application (since batteries are outside) I’m more concerned about keeping the batteries warm in the winter. It only gets down to roughly 20 degrees in western Tennessee. I put a lighter torch on one side of the insulation and I could not feel the heat on the other side after a min of constant flame. good insulation! I purchased a seed incubator pad heater. It’s 3”x 20”. It only uses 5w at 120v. Heater will be connected to a bestek thermostat relay (Same one I use for the wood boiler). I figure I only want to keep the batteries above freezing (probably 40f). So the little heater should work for the small area. I got the seams sealed up with metal tape.

I’ll add some pics once the batteries are in the box. I’ll have to wait for 18pin connectors from China to arrive for the bms so I can add the bms leads to the batteries. But I’m going to get the batteries installed outside and hooked back up to get things running again.
Other things in the pics are weather tight connector for 1 1/2” flex and aluminum power distribution blocks for positive and negatives so all batteries have the same length wires. ;)
 

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nz, if your asking me. The lid fits on snug but it’s not 100% airtight. It will not build up much pressure. I will use putty in the flex conduit to prevent gases from entering the house
 
Everything’s put back together. Batteries in their new home. Waiting on connectors to finish bms install.
 

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Killowatt, thanks for starting this thread.
I am still processing by cells, but plan on putting things together in February or so (dang it takes a long time to process a couple of thousand cells with just two Opus--MegaCell chargers on the way, I hope).
I too have no other option but to have the powerwall inside my house--simply no way to even do it in the garage that I can see right now; although I am still working on that.
I have not seen news reports of a serious problem with DIY powerwalls catching on fire, but of course I know it is possible. I plan to fuse each cell with a 1 amp quick blow fuse (with a 160 P system, I will never be calling for 160 amps--heck I probably could fuse them with 0.5 A fuses).
I will watch this tread for ideas, possible cabinets that will make things safer.
If I think of any thing (HA!), I will pass it on.
 
Dr Dickie: The fuses on the cell should be 4x your current per cell based on main fuse. Do you want to swap 160 fuses or 1?
So if your max is 1A per cell your cell level fuse should be 4A. Its still well below what a cell can push.

Best thing is outdoors in each own cabinet FAR away from any building. Just like Tesla do among others.
 
Mmm, okay, based on 4X I will go with 2A fuses, as pushing 80 Amps at 48V would probably be what I consider to be the max (close to 4 kWs). Probably a 2 or 3kW inverter would be the max (then consider 2X for pulse--which I would never want to hit).

I know that outside is best, just do not think it is possible as of right now. BUT, the more I think about it, the more I am going to work on a way of getting it into the garage--though, since the garage is attached to the house, it really does not seem to be that much of a difference. Since I still have about a thousand cells let to process, and waiting a month for self-discharge after capacity testing the last batch, I got a couple of months to work on getting it into the garage:LOL:
Thanks daromer
 
Remember that its not about fusing the current from the individual cell but rather the current from the rest of pack trying to flow thru a cell that has turned into a short. Any significant pack will generate a lot of amps - so fuse or fuse wire need not be so precise as long as the rest of the pack has sufficient amps (when shorted) that it to blow or melt.
 
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