Aluminum Box for 18650s - Fireproof?

OffGridInTheCity

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Hey Folks
I was just watching @jehugarcia building an aluminum 'box' for 18650s... -

Do you think the kind of box shown in the youtube would actually 'contain' a cascading fire event? or would it just melt thru the aluminum? or would fire melt/shoot thru the wire holes? Does anyone know how thick the metal must be?

My powerwall is exposed on 1 side (you can see it in my user id icon to the left) and I was thinking that it's in my skill set to buy aluminum sheets and angle brackets and screw them together to form boxes. Its 7000 cells, a heck of a fire if it started cascading. The 4/0 + batrium wires need to penetrate thru holes. I just don't have a sense of how thick the metal needs to be or how 'tight' the box has to be to avoid fire melting the metal or seeping out the edges or holes. If I build one, I'd like to think it could actually do the job :)
 
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not2bme

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Probably not aluminum. The melting point of aluminum is pretty low. Figure it'll burn through if hot enough. I use a horizontal/lateral filing cabinet for mine. Fits nicely and made of steel. Cheap and easy to find on craigslist.
 

hbpowerwall

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It would slow it down - I guess that's a bonus. If i have learnt anything in the past 24 hours it's that I don't do enough to keep my random cells safe..
 

floydR

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LG RESU's are composed of (5mm-6mm) aluminum sides and heavy sheetmetal /plastic tops and bottoms.
Later floyd
 

kc8adu

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you also want to vent it outside in such a way that if there is a catastrophic failure the resultant blowtorch possible at the end of the vent wont ignite anything.
tight enclosure=bomb.
 

OffGridInTheCity

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I think the 48" may allow for a 14S battery (though that will be very close).
Yes. My packs have 6AWG busbars (sticking out on each side) and sitting 14s side-by-side on a 48" long shelfs. They aren't crammed in, a little loose and they fit nicely in 48".
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Dr. Dickie

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Yes. My packs have 6AWG busbars (sticking out on each side) and sitting 14s side-by-side on a 48" long shelfs. They aren't crammed in, a little loose and they fit nicely in 48".
View attachment 23101
View attachment 23102

Thanks OffGridinTheCity, I have my 14 160P packs (currently without cells except at the corners sitting on the floor and that was what my measurements gave me. It always makes me feel much better when I get verification (as I have been know to do some really stupid stuff).
Most cabinets come with 36" across--which would have caused me a lot of problems.
NOW to try to find the room in the garage next to the service panel.
 

daromer

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The importance on a cabinet is that ventilation is directed to an open area.
If using alu you need decent thickness and even one hightemp graded one i suspect. The cheaper ones melt rather quickly. With that said 5mm as example need quite some heat and alu is good heat carrier.
 

anton_voltx

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Measured flame temperatures as high as 1069 °C for single cells [8] and 1500 °C for a battery module [9] have been reported.
An experimental study on thermal runaway characteristics of lithium-ion batteries with high specific energy and prediction of heat release rate
Link

For starters make sure the casing can contain over 1500 °C.

Here is a list of common metal melting points. Link
  • Aluminum: 660 °C
  • Stainless Steel 1510 °C
Melting point does not mean catastrophic failure or that the casing can not contain the spread of fire -- but it is the beginning of those processes.

If you really want to be full-proof you could to introduce an extinguishing agent like they use on airplanes.
 

Dr. Dickie

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I am currently sitting at home, waiting for the text to tell me of delivery of:
It will go into my plastic shed.
When I get it in, I will decide whether or not I can squeeze 14 packs across the back safely.
Then, I am going to finally decide on whether to do a 160P in 4 x 40 configuration or 8 x 20 configuration.
 

OffGridInTheCity

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I am currently sitting at home, waiting for the text to tell me of delivery of:
It will go into my plastic shed.
When I get it in, I will decide whether or not I can squeeze 14 packs across the back safely.
Then, I am going to finally decide on whether to do a 160P in 4 x 40 configuration or 8 x 20 configuration.
NICE! I wish I had room, it looks perfect dimensions for 14s packs. As far as stopping a cascading fire... I think @daromer (or someone with experience) commented that 'venting' is a key component of the fire containment strategy. Do you plan to vent the cabinet somehow?
 

floydR

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If you really want to be full-proof you could to introduce an extinguishing agent like they use on airplanes.
theses systems work to exinguish the fire but Not the reignition of the fire for this you need a cooling agent, water is used to cool the components until they no longer reignite. Unless something new has been invented that can actually extinguish the fire.
 

anton_voltx

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theses systems work to exinguish the fire but Not the reignition of the fire for this you need a cooling agent, water is used to cool the components until they no longer reignite. Unless something new has been invented that can actually extinguish the fire.
That's interesting thanks. I don't know the details but I do know many flights now carry a small metal box with an extinguishing agent or a containment bag to extinguish small lithium-ion fires. The halon gas in the cargo hold can also suppress the fires, but it's complicated and has to do a lot with thermal runaway and how many cells are on the flight and so on if it's going to be effective. I have heard of cases where they suppressed the fire with gas and then landed to extinguish it with more traditional means (most likely a lot of water).
 

Dr. Dickie

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NICE! I wish I had room, it looks perfect dimensions for 14s packs. As far as stopping a cascading fire... I think @daromer (or someone with experience) commented that 'venting' is a key component of the fire containment strategy. Do you plan to vent the cabinet somehow?
Yes. I will have to vent it to allow cooling (fans) during summer.
I have to get it, and then I can start laying everything out.

Okay, it came. Now I need to get the time to put it together. Oh boy, more stuff to do.
 
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