Fire Safe Cabinet


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2weiund2wanzig

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Jun 21, 2020
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I found an old, very sturdy, steel metal cabinet on ebay. Sanded off some rustand put some nice finish on it.
It is big enough to keep my planned small powerwall (only for excess power) of about 1kwheasylyin it.
I think the steel is somewhere between 0.5m an 1mmthick (will measure it later), defenitly thicker than the modern electrical house fuse cabinets (however thats called in english :)).
Now i am thinking about if i should add some fireproof material like dry wallconstruction sheetson the inside or if i should leave it and only put some coating in it to prevent electrical shorts to the cabinet.

The cabinet with the powerwall will be in the basement (washmashine and heating) room of my brick built house and there are nearly no burnable things inside that room.

What would youdo? Leave the metal cabinet or add fireprove material on the inside?
 

floydR

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Add drywall or better yet concrete backerboard (tile backer). I have seen Charging boxes made from 19 mm drywall joined together with drywall dust and white glue. I made a small box for charging the 3s lipo battery I have for my welder. if I can find the link with the details on how to make the charging box I will post it here.
Charge it only while you are there. From what I read that is how the RC community recommends charging is done. BMS required unless you use a balance charger.

Later floyd
 

2weiund2wanzig

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floydR said:
[..]concrete backerboard (tile backer).[..]

Im not sure if we have something like this here because we don't usually have wood frame constructed houses here.

And hmmm. charging only when i am there wouldn't be an option on a powerwall :huh:
 

Jim Jr.

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floydR said:
Add drywall or better yet concrete backerboard (tile backer). I have seen Charging boxes made from 19 mm drywall joined together with drywall dust and white glue. I made a small box for charging the 3s lipo battery I have for my welder. if I can find the link with the details on how to make the charging box I will post it here.
Charge it only while you are there. From what I read that is how the RC community recommends charging is done. BMS required unless you use a balance charger.

Later floyd
Possibility of a fire proof file cabinet they have one hour rating and are sealed ? I have one 4 drawer I use for my LTO's

JimJr
 

floydR

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1 kWh could be a portable generator. Here is a 3.5 kWh solar generator made.
later floyd
 
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ajw22

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Nov 16, 2018
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JimJr. said:
Possibility of a fire proof file cabinet they have one hour rating and are sealed ? I have one 4 drawer I use for my LTO's

I think fully sealed containers areusually not a good idea when storingvolatile stuff, because fire/heat will increase the insidepressure until something bursts open violently. You'll probably want something thatsafely vents out.
 

Jim Jr.

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ajw22 said:
JimJr. said:
Possibility of a fire proof file cabinet they have one hour rating and are sealed ? I have one 4 drawer I use for my LTO's

I think fully sealed containers areusually not a good idea when storingvolatile stuff, because fire/heat will increase the insidepressure until something bursts open violently. You'll probably want something thatsafely vents out.

Apparently, you never have seen one , the file cabinet variety only have a labyrinth seal of non burnable material , no pressure buildup

Jim jr
 

gauss163

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Jun 28, 2020
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In addition to the fire and explosion risks, it deserves to be much better known that Li-ion fires produce large amounts of toxic gases (which is why firefighters useSCBA = self contained breathing apparatus). In particular, even a single cell fire already produces unsafe levels of HF (hydroflouric acid), so imagine what hundreds of burning cells can do. Even a small amount of HF inhalation can lead toserious and long-lasting health problems. So you don't want to be anywhere near a burning huge pack like a powerwall. These risks are quite real (not simply liabilitymotivated FUD).

If you peruse the above CDC link you'llsee that one particularlynasty aspect of HF inhalation is the possibly delayed onset of symptoms, e.g. it may take a few days forpulmonary edema (fluid in lungs) to rear its ugly head, and this may in turnlead to chronic lung disease. So if you are ever exposed to gases from a Li-ion fire always seek medical treatment immediately, even if initially you don't notice any problems.

There are many studies showing these risks, e.g. one from last year:park et al, Risk assessment of lithium-ion battery explosion: chemical leakages, Journal of Toxicology and Environmental Health, Part B, 1-12, (2019). Below is an excerpt of the abstract:

Use of lithium-ion batteries has raised safety issues owing to chemical leakages, overcharging, external heating, or explosions. A risk assessment was conducted for hydrofluoric acid (HF) and lithium hydroxide (LiOH) which potential might leak from lithium-ion batteries. The inhalation no-observed-adverse-effect-level (NOAEL) for HF was 0.75 mg/kg/d. When a lithium-ion battery explodes in a limited space, HF emissions amount to 10100 ppm. Assuming the worst-case scenario, the conversion rate was calculated to be 81.8 mg/m3, and the average daily dose (ADD) was 19.5 mg/kg/d. Consequently, the margin of exposure (MOE = NOAEL/ADD) was 0.034, a value which constitutes an unsafe inhalation exposure for HF.
 

Jim Jr.

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Jun 3, 2018
Messages
65
gauss163 said:
In addition to the fire and explosion risks, it deserves to be much better known that Li-ion fires produce large amounts of toxic gases (which is why firefighters useSCBA = self contained breathing apparatus). In particular, even a single cell fire already produces unsafe levels of HF (hydroflouric acid), so imagine what hundreds of burning cells can do. Even a small amount of HF inhalation can lead toserious and long-lasting health problems. So you don't want to be anywhere near a burning huge pack like a powerwall. These risks are quite real (not simply liabilitymotivated FUD).

If you peruse the above CDC link you'llsee that one particularlynasty aspect of HF inhalation is the possibly delayed onset of symptoms, e.g. it may take a few days forpulmonary edema (fluid in lungs) to rear its ugly head, and this may in turnlead to chronic lung disease. So if you are ever exposed to gases from a Li-ion fire always seek medical treatment immediately, even if initially you don't notice any problems.

There are many studies showing these risks, e.g. one from last year:park et al, Risk assessment of lithium-ion battery explosion: chemical leakages, Journal of Toxicology and Environmental Health, Part B, 1-12, (2019). Below is an excerpt of the abstract:

Use of lithium-ion batteries has raised safety issues owing to chemical leakages, overcharging, external heating, or explosions. A risk assessment was conducted for hydrofluoric acid (HF) and lithium hydroxide (LiOH) which potential might leak from lithium-ion batteries. The inhalation no-observed-adverse-effect-level (NOAEL) for HF was 0.75 mg/kg/d. When a lithium-ion battery explodes in a limited space, HF emissions amount to 10100 ppm. Assuming the worst-case scenario, the conversion rate was calculated to be 81.8 mg/m3, and the average daily dose (ADD) was 19.5 mg/kg/d. Consequently, the margin of exposure (MOE = NOAEL/ADD) was 0.034, a value which constitutes an unsafe inhalation exposure for HF.

The fire proof cabinet can be vented to the outside with stainless steel double wall furnace pipe . With silicon sealer to prevent backing up into the inside room.The sealer will also prevent any additional oxygen imput to the fire :idea:

Jimjr
 

gauss163

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camthecam said:
Just vent into neighbours house.

Yes, choose carefullywhere you aim the vent. Li-ion fires generate huge amounts of flammable gases, so it may amount to a monster flamethrower that would make Elon's Musk's look like a toy. For some numbers, here it is claimed that they produce 330L/kWh of flammable gas (p. 57), and it is recommended to have aforced ventilation rate of 0.32 cfm/kWh (p.48).

For example, a 2019 Li-ion fire in a battery substation in Surprise, AZ generated a flame 75 feet long by 25 feet high that threw a firefighter 75 feet.
 

Jim Jr.

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gauss163 said:
camthecam said:
Just vent into neighbours house.

Yes, choose carefullywhere you aim the vent. Li-ion fires generate huge amounts of flammable gases, so it may amount to a monster flamethrower that would make Elon's Musk's look like a toy. For some numbers, here it is claimed that they produce 330L/kWh of flammable gas (p. 57), and it is recommended to have aforced ventilation rate of 0.32 cfm/kWh (p.48).
Read the pdf. The container sized fire storage looks like a hell on earth occurrence :D . Maybe they should adopt the fireworks

storage with high earthen walls to prevent fire radiating to adjacent containers.

jimjr
 

gauss163

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JimJr. said:
Read the pdf. The container sized fire storage looks like a hell on earth occurrence :D . Maybe they should adopt the fireworks storage with high earthen walls to prevent fire radiating to adjacent containers.

Large pack(powerwall)fires needn't be so bad if the pack is properly designed, e.g. see here for a test on a g2 Tesla powerpack. But that's using state-of-the-art tech to improve safety(mostof which - alas - is currentlyimpossible to emulate inDIY powerwalls, e.g. tweaks to cell chemistry, separators, highly customized BMS, etc).
 

Jim Jr.

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gauss163 said:
JimJr. said:
Read the pdf. The container sized fire storage looks like a hell on earth occurrence :D . Maybe they should adopt the fireworks storage with high earthen walls to prevent fire radiating to adjacent containers.

Large pack(powerwall)fires needn't be so bad if the pack is properly designed, e.g. see here for a test on a g2 Tesla powerpack. But that's using state-of-the-art tech to improve safety(mostof which - alas - is currentlyimpossible to emulate inDIY powerwalls, e.g. tweaks to cell chemistry, separators, highly customized BMS, etc).
I was referring to my partner in the magic smoke department , John Murphy ------- Murphy's Law :D :D :D :D :D


Jim jr
 

100kwh-hunter

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Mar 2, 2019
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Promatec or vermiculite sheets.
From both sheets you can easy make a chimney to the outside.
Both materials are very fire proof and very good insulating.
As mentioned before: a proper designed power wall is very safe--->fuses on each level.
If i remember correctly, Korisan made a topic about this, from cell level fusing up to your solar panels or generator.
For cell level i strongly recommend glass fusses!
Best, Igor
 

Stefanseiner

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Apr 16, 2020
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I just finished my fire safe cabinet a few days ago.

It's an old metal box too. I sanded and painted it new

image_hnhzth.jpg


then some works for thermal care.

image_gltdej.jpg


I dont want the box to be 100% airtight, but I want to keep the fire into the box if there will be one, so I don't want to use an open ventilation system.

image_jormmw.jpg


Using some computer cpu cooler (Intel boxed cooler) at the inside...

image_xankjd.jpg


...and some 100 x 100 x 18mm passive radiators...

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...with thermal paste...

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...at the outside

image_pklgtu.jpg


will be tight fitting for the 14s60p system

image_ppwunz.jpg


fermacell at the boddom and 40mm mineral wool WLG032 (fireproof 1.000C +) at the walls

image_vkspgz.jpg


getting even tighter but fits

image_ryqjzo.jpg


7 packs in parallel...

image_aoxcgm.jpg


...intermediate floor with fermacell...

image_ntsygb.jpg


...and 7 more packs

image_vmspuo.jpg


all packs are separated with fermacell separators with 12cm in high = 2cm more then the packs to ensure ventilation.
In front some space left for cables and connectors

image_ascccz.jpg


BMS / active balancer, 100A DC circuit breaker, voltmeter and fan controller (not on this picture, now it's mounted at the left of the bms)

image_upcewv.jpg


another 40mm of mineral wool on top

image_ljbjlb.jpg



image_khoyje.jpg



image_xmhxhy.jpg



image_lnlhdv.jpg



image_odqmin.jpg


now I am running some tests to evaluate the thermal developement.

image_hexzmy.jpg


But as far as I can say at this time, the temps inside the box are OK and stay below 30C at a maximum discharge current of 30 ams = 0,5A per cell

image_vxwasa.jpg


the load test is not done yet and I will try to load twice of the current = 60A / 1A per cell so that the powerwall can easily fully charged in one day
 

2weiund2wanzig

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Jun 21, 2020
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Hey, it seems like you made a lot of thoughts about this before you built it.
The only thing i wouldnt like is not t o be able to see the cells quickly, especially the lower story/floor of your box.

Which BMS is that?
 

Stefanseiner

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Apr 16, 2020
Messages
136
2weiund2wanzig said:
The only thing i wouldnt like is not t o be able to see the cells quickly, especially the lower story/floor of your box.

Yes I already noticed this disadvantage too.
But the main goal of this powerwall for me is to learn and figure out some weak points of construction and in the building process.
It's my first test-build before I go to the bigger 14s240p system which will be into a bigger fire proof metal cabinet where I canmaintance each pack more easily then with this box.


2weiund2wanzig said:
Which BMS is that?

You will find it on Aliexpress with keywords "active balancer bms 24s" for example here ->IC GOGOGO Store
On eBay too but mostly much more expensive.

There are a few different versions with 0,6A balancing current, 1A and 2A, and each version with different charge/discharge currents. All versions are usable for 13s to 24s systems.
I am using the 2A / 150A version, costs about 140USD
 

Stefanseiner

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