DIY firesafe casing - Test

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drbacke

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Joined
Apr 3, 2019
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60
Hey guys,
as I mentioned in another Thread before, I did a test of my diy casing for the lithium packs.
I build a small version and ignited6 and 12 Lithium Batteries inside the small casing.
It was a serious test, but I'd be lying if I said we didn't have fun.
I hope you don't think I'm crazy now. But the test actually calmed me down a lot because I trust the case more.

Here is the result,I found it very promising:

Here is the big version of my box, the packs above the the lithium packs tiny hollow glas balls escpecially madefor metal fire. They should fall down in case of heat and withdrawthe termal energy for melting:

image_jsjiqp.jpg
 
What are your "Brandschutzplatten" exactly ? "Gipskartonplatten" or someting special ?

I admit in the beginning i didnt recognize the value of the firetests you wanted to perform, but having seen this result i stand corrected:
Good work and really interesting result.

(All Germans in one thread ?)
 
Nope not all germans in this thread(-: also dutchies...

Clever findings, i was also planning to insulate with rockwool and "gipskartonplatten".(drywall sheets plaster)
Thanks for this info and video.

I trow some heaters in the fire outside and get a similar result, big flames even a bang or two.
Is it a idea to put some on a electric heating plate, those plates warm up to 460 degrees celsius max.

Thanks

What was the fire starter in you're first test btw, gunpowder or just match heads grinded up?
 
It looks like it takes a fair bit of energy to get cells to burn.
Even after cells burned, it took the heat gun to make more burn.

Do you have any idea what temperature the box was when the cells started to burn?
 
Theory says 130 degrees make the cells run away. The separator fails at that temp.
 
I think there was a little bit more temperature in that "chamber" than 130

That's why i suggested and hoping for a test with a electric heating plate.
You can figure out the temp on those things.

Speaking frankly......I hope he will do the test, I was planning to do it but it will save me some time.

For a temp sensor for those kind of temps, look for furnas build(force, melting oven ect)....I have two...cant remember the name...german make btw.
You can order cheap sensors for temps between 800 and 2500 degrees celsius.
Or go to a lower temp and use a oven thermometer(max 400), or for lead casting stuff(400 to 900 degrees celsius)

My 2 cents.
 
Oz18650 said:
It looks like it takes a fair bit of energy to get cells to burn.
Even after cells burned, it took the heat gun to make more burn.

Do you have any idea what temperature the box was when the cells started to burn?
Click to expand...

The first reactions came after a relatively short time (1-2min). Usually a "Plop" and then is the cellside wall burst or the overpressure valve. After that the cells only smoke until they run out. That the cells really burned, occurred only very rarely.
In "Electrical safety of commercial Li-ion cells based on NMC and NCA technology compared to LFP technology - Brand et. al." is a more precise measurement of the termal runawaytemperatures. But no cell in their tests exploded or burned. The CID or the overpressure valve prevented that very safely.
But measuring the termal runaway temperaturewas not my goal, I just wanted to see, wether the casing material can stand the extremetemperatures or not.
And it was no problem at all for the material.
 
drbacke, well done. I'm planning a similar design for my box, but a few more boxes. I'm pleased to see that your material hold up rather easy. I am planning to use fiber cement board, and my concern was that a possible explosion could break the box and leak to the next. All in all, with big vents, it seems like the chance for a group pressurized explosion to break the box is rather low. Possible not impossible, but low. I'm also investigating some silicone to join the array of boxes, which is fire proof. Also, the nice bit it that if all that goes bad, does not go bad for too long, you would not have a fire for a long duration. Now there is still the plastic burning for a period of time, and plastic, can burn for some time. I'm planning in using HDPE for the holders.

Nice work.
 
Regalo said:
drbacke, well done. I'm planning a similar design for my box, but a few more boxes. I'm pleased to see that your material hold up rather easy. I am planning to use fiber cement board, and my concern was that a possible explosion could break the box and leak to the next. All in all, with big vents, it seems like the chance for a group pressurized explosion to break the box is rather low. Possible not impossible, but low. I'm also investigating some silicone to join the array of boxes, which is fire proof. Also, the nice bit it that if all that goes bad, does not go bad for too long, you would not have a fire for a long duration. Now there is still the plastic burning for a period of time, and plastic, can burn for some time. I'm planning in using HDPE for the holders.

Nice work.
Click to expand...

This sounds like a very interesting project, which kind of battery do you plan to use?
In my experience the "explosion" of genuine 18650 is not really powerfull and in most cases there is no explosion. Maybe generic "china" cells are more dangerous if the overpressure valve is not designed well. Also the cells doesn't burn at once, the spread is a slow but insidious process

If it will all burn: No one can tell you what happens. But with a well designed casing, you'll have a greater chance of a safe course.
Of course the important thing is not to let it get that far.
 
Nice test. I was also thinking of using drywall pieces between cell groups. There's fire-resistance drywall as well, it's got a pink wrapper, instead of the green seen on your video. Green ones are for humid places, actually. I have an important question, though: What kind of cells were you using? Were they end-of-life cells? I believe everything would be much more violent if you were to use new, high-capacity, fully-charged cells.
 
Please dont use hdpe, if that burns, it will be very hard to put out.
It smokes like rubber.
 
100kwh-hunter said:
HDPE.....DONT USE....FREAKING DON'T USE

DON'T YOU DARE
Click to expand...


Please elaborate as to why. Other than "It's plastic"
 
DrBacke, I'll be using the 18650's. Bit busy going through them. What a tedious winter job.

100Kw, the burning plastic is a concern, yes. I'll burn a piece, and see if I can find less burnable plastics, but as Korishan suggests, I think my luck will be out.
 
Quick thought:
I think a plastic named pp or pe will suit your needs, i thought it only melted by very hot temps and its difficult to make it burn.

I am planning to make for every pack a brick "room" like a wasp nest, or with vermiculite board.
Vermiculite board is just like wood to work with.
I am going to use some drywall sheet, for every cell there will be a hole on both side's with i put a cap in it.
The goal i would like to achieve is, if one cell goes bad, the sparkles wont go/reach to the rest of the pack and only pops the cap.
That li ion gas, is like a firecracker broke in half when it ignites, a very hot greenish blueish color, might burn hotter than a acetylene gas torch
When a cell ignites it will burn for a ~10-15 seconds, i think this is enough time to set dry wood on fire.

So packs are fireinsulated from each other and if a cell goes bad the flamewon't reach other cells.
Its costing enough time and money already, so this extra mile is a small step
Did you ever thought about epoxy resin to combine? It will extend the fireproof time long enough.

Those were my little thoughts
Thanks for sharing, best
 
Daromer did some very interesting experiments, it is a good guide line for me to protect the other cells for if one goes awol.
When i am ready to make some protection, i will share some pictures of course.

Best
 
Has anyone thought about the flame retardant coatings that are available? There are coatings rated Class A. An intumescent paint is actually supposed to create a foam fire retardant when heated to a certain temperature.Certainly might be of interest for at least a battery that is made to be portable in some way .... or maybe even a solution to what this whole thread is about if the net result of any material is to slow the fire down. Here is Youtube video on one manufacturer's paint ...I think the later segment at around 2:29 is the more relative to our concerns about containing a battery fire.

 
Someone built their packs in PC cases (eg cheap steel boxes)
Maybe these could be lined with cement board.
Regular drywall might not be so good as surfaces are only thick paper (burns) & centre only chalk (physically weak)?
 
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