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Stefanseiner

Member
Joined
Apr 16, 2020
Messages
128
You may have a look at this Topic: Fire Safe Cabinet
image_vmspuo.jpg
I am using three of this metal boxes with fireproof inlay. Just fitting for a 18650 14s60p system.



And as an alternative to the expensive cabinets on Amazon which Dr.Dickie posted I can recommend a locker. The older ones are build with stable metal and cheap, in my region they cost about 30USD for a triple-locker

actually I am moving my growing powerwall from the box above into such a locker
fire safe locker for diy 18650 powerwall (1).jpg

rockwool (fireproof > 1.000°C) on the outer walls
fire safe locker for diy 18650 powerwall (2).jpg

welding some more metal shelfs
fire safe locker for diy 18650 powerwall (3).jpg

fire safe locker for diy 18650 powerwall (4).jpg

10mm fermacell (fireproof > 1.000°C) on all metal and...
fire safe locker for diy 18650 powerwall (5).jpg

...as separator between all packs. Not on picture but the lower bank now has a fermacell plate on top so fire can't jump from one pack to another
fire safe locker for diy 18650 powerwall (6).jpg

fire safe locker for diy 18650 powerwall (7).jpg

fits very tight, this are 2 independent systems 14s60p.
The door will get a rockwool too. Oh, and now it's sanded and newly painted
fire safe locker for diy 18650 powerwall (8).jpg

The top compartment (the original shelf) is free for the BMSs, cables, switches and so on. This will be my work today and at the weekend
fire safe locker for diy 18650 powerwall (9).jpg
 

100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
Or make dry wall casings per pack? how long does a li ion cell burns?
Put the "explosion lid" on the top and the rest of your pack's wont catch fire or will heat up.
Fuses will blow and the pack is electronically insulated?
Rockwool has a insulation bonus..go with 5 cm or two inch, this will save you a lot of heat loss, probably even no need for extra heating..depends on where you are located ofcourse...north pole or the Sahara,,small difference?

To put out a lithium fire you will need to choke it, now halon gas is not allowed anymore but his replacement, i thought it was hs500 or something was a very good alternative, you can create a sprinkler system on top of it with a small pressure tank and a container with that ?hs500? stuff, heat above 60 or 80c (depends on your sprinkler) and your system will empty itself and stops heat spreading, contain the fire, with undamaged cells that did not catch fire or over heated..once i tried to do a group buy here to reduce the cost.
The firm was i thought based in the Netherlands(or a reseller..)

Hope this helps, my two cents.

With best regards
 

100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
Or make dry wall casings per pack? how long does a li ion cell burns?
Put the "explosion lid" on the top and the rest of your pack wont catch fire or will heat up.
Fuses will blow and the pack is electronically insulated?

So 0C is 0C no charging and no discharging? for li ion?
 

100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
ps do NOT charge or discharge them above 45 C this i know for sure that i will cost you cycle life.
Above 55C they will vent and can couse fire
above 65C...enjoy the fire
 

Redpacket

Member
Joined
Feb 28, 2018
Messages
1,302
It's good to keep in mind that when a cell burns, it is actually releasing a fixed amount stored energy "fast".
Like you can see in youtube videos, once this has happened, there's not much left apart from a bit of plastic or two that keeps burning.
IE it's a bit like a firecracker, a short hot burst of heat, then little.
It's not likely to burn for hours.

So IMHO, fire management could be best focused on
a) containing a short intense burn (maybe with suitable venting, maybe allowing for a few "bursts of heat" as close cells burn)
b) separation to stop it spreading to adjacent packs/cells
c) not igniting nearby materials
 

100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
@Redpacket
Exactly my thought, but English is not my native language (sorry) and i refuse to use google translate...
But i have a experiment in my mind, to burn/blow up/over charge a 20p pack in between some empty cases..
I have a suspicion when i "isolate" with the drywall and add a "blasting cap", the other cells will not find any extra heating or short circuit or sparks etc.

BUT (yes the everlasting pain in the ass: the but) when your wall is growing bigger and your dis and charge are around a 250mah per cell or even lower i dont think you need those kind of protection...but this is just an educated guess.

What do you need to let a cell ignite, some over charge..
One cell, 6v 12 hour waiting time and/or a 5a drawing when it become a heater or a self discharger...
By this time a fuse would have done its job....especially when you have a big power wall and fused your cells with one A or less..
I had a total of 106 kwh power wall fussed on cell level base with 0.5a per fuse(not going to do that again..)
I could abuse the powerwall with a pike with a max with everting on....... incl whole kitchen and airco ect a whooping 0.075A per cell....crush your number would be in order and adjust that to your fuses.

Oke for a start up the first 10-20-30 heck even 40 kwh powerwall go with protect at cell level.
In the long run they will get weaker and might be an sd...i will not take my chance..
If one cell goes awall it can take your whole powerwall and thus your house down.
Test your cells...
Even in that event, i would like to just replace one pack of cells, per 10 or per 200...its one pack...one cell was the trouble maker...
Isolate it with a fuse so others can not "dump" there load into that cell and isolate that pack of the rest so it can not heat up the rest in those 5 minutes...
On the other hand there are people that have 200!!!!!kwh!!!!!li ion!!!18650!!!! powerwalls running for 10 years and still expanding and testing there cells(oke at pack level after a year) and all is oke, but they have safety build in, and must replace a cell or pack frequently.
I think dry wall sheet is perfect to maintain and control a fire(explosion lid example) to preserve other loaded packs to catch fire.
It is what.... burning for max 10 minutes....it is not even able to boil my egg...
But prevent is better....

Test your cells at 1 to 2A in one hour...charge discharge and do it again....find those heaters and self dischargers after 2 to 4 weeks for v drop
How you test is the first safety you will get, how you built your packs is second, how you charge and discharge is probably the most important after your fuses...

I would like to have my powerwall in 50 cell sections with fusses (5a for 10 cells) in one separate chamber...there is one man here that test his cells better than me(as far as i know)...i also use IR.
Some use "survival of the fittest" but have fuses in the right places....
Its your house, your insurance company, your electric bill, what does a dry wall sheet cost? 244cm by 122cm in my country not even 10Euro...
Make a cactus rack(any carpenter can shim in please).....

Sorry for the jibberjat and story, i geuss i was in my "writing seat again"
My two cents, with best regards Igor
 

OffGridInTheCity

Active member
Joined
Dec 15, 2018
Messages
1,738
My question is about gracefully aging cells -> dendrites? --> fire???

My powerwall is working fine, low charge/discharge amps, moderate operating range, moderate ambient temps, cell level fusing, Batrium BMS/shunt-trip, and constant monitoring. NO WAY will this thing go up in smoke due to overcharge or charge/discharge abuse - way less risk than driving the car.

However, I just don't understand the risk of dendrites. In particular, if a pack has degraded to <60% of original capacity is it more dangerous than when its at 90%? What about 40% etc. Could the pack be OK but 1 cell in the pack go up due to dendrites? I'd like to understand this aspect of risk better :)
 

Redpacket

Member
Joined
Feb 28, 2018
Messages
1,302
It does seem power wall use is pretty mild, eg compared to power tool, RC, vaping or spot welding packs!
Spontaneous short circuits would seem to be the main risk source.
eg from a dent, careful builders discard any, but maybe accidental damage by handling a pack (but you're close by then)
or metal shaving/solder bead, etc in cap end, eg Sony laptop fires issue or fuse wire short (ironic right?)
or dendrites, supposed to be worse if low volt cells are "recovered" eg with pulse/burp kick starts, etc

Another material for fireproofing might be cement board (various names, eg hardiplank, villaboard, etc here in Australia)
Mine are in steel cases in shed separate from house but they are LiFePo4 not Li-ion so less risk there.

Edit: added:
re dendrites - my understanding is when the cells are under approx 2V for a bit, the metal electrodes in the cell partially dissolve. When that cell is recharged, the dissolved metals will plate back out, but some may form into crystals with sharp points which can puncture the thin insulator membrane.
It can short to the other side electrode, shorting the cell = fireworks/heating.
 
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100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
My question is about gracefully aging cells -> dendrites? --> fire???
Yes and no, as far as my knowledge reaches, if a cell ages gracefully it will consume itself.
To the point there is nothing left, in this case if that cell is "suicidal" your fusses must kick in.
A cell that will "self destruct" will consume a lot of power from his connecting cells in that pack up to the point of your fuse.
Thats why there is a "cell level fuse".....some use 5a fusses, some like to use 0.250a or even smaller fusses per cell
Some use a 5A fuse at 10 cells...( i am going to use 5a fuse at 10 cells at 2700mah a cell, i did 0.250A even 0.100a fuse per cell, still working)
Depending on the size of your power wall you must adjust your fuses to your feed and use and check them(cells/packs) once in a while.
Retest them.
Or a cell will not store more than 20% of its original capacity, you will find out when your bms is telling you there is something wrong.
Or after a year and you test the pack there is not much of the original capacity left....

However, I just don't understand the risk of dendrites. In particular, if a pack has degraded to <60% of original capacity is it more dangerous than when its at 90%? What about 40% etc. Could the pack be OK but 1 cell in the pack go up due to dendrites? I'd like to understand this aspect of risk better

Dendrites will cause the internal resistance to go up and thus the amount of power needed to charge a cell is also going up, the same for discharge.
You want to look at this as if it is a coffee filter(old fashion paper type(the best coffee btw)) if the smallest holes will clog the bigger holes will eventually do also, but you will taste it as your coffee is getting bitter..
So reusing a coffee filter is a no go for me because i would like to have no bitterness in my coffee...
(the best coffee btw is to boil 2 to 5 min!) it and let it sink, boil it AGAIN let it sink again, turn off the heat imminently after the water reaches the boiling point, stir in between and scope the edges))

Same as your cells, i like my coffee, thank you batrium.
Dendrites are just those small particals that are clogging up your filter, they dont allow movement between the anode and he cathode anymore, the filter is full and the resistance is gaining to get some charge into that cell.
Thus making them into heaters or very slow chargers or discharges, batrium will tell you if there is something going on.
But when they consume to much(cell level) the fuse will blow...

Spontaneous short circuits would seem to be the main risk source.
eg from a dent, careful builders discard any, but maybe accidental damage by handling a pack (but you're close by then)
or metal shaving/solder bead, etc in cap end, eg Sony laptop fires issue or fuse wire short (ironic right?)
Main origin of this problem is indeed careless builders.
THROW AWAY your dented cells OR heaters OR cells that wont take more/less than 1amp an hour when testing...
My testing is a fall out race
I test for Self dischargers
Heaters.
Time, they must take a certain amount of a in a certain amount of time.
IR
ect ect
I will rewrite a old topic soon, i have more good feelings for a fall out race(earn your place in the marine corps, my boy...)....than a survival of the fittest race

Spontaneity shortcut....(Johnny no5)
Spider, fly, leaking roof, rust on your cells not even(will get back to that one) branches what ever event...short circuit is YOUR FAULT...PERIOD...
Keep it clean no dust, no moister, no dogs/kids on the lose with saliva...make sure youre welds or your soldering are in good order....

Keep them(cells) in a good room, possible air tight, with a dehumidifier in it below 40% RH, you will be fine...even the ones that started rusting allready, but this i am not sure: no more moister...rust will not grow or eat further..again on this one i am not sure...
If rusted concrete iron bares are poured in and after 6 months you need to destruct it they are clean as the just came out of the oven.....oxygen did not reach the bars, rust did consume itself.
If there is some freezing over steel/iron will not rust because there is no moister/ thus the rust that was there will not gain in size or depth...but those are for steel concrete castings, but the rusted walls where CLEAN after 4 months of -10C...and lower temps...ake no moister.

Another material for fireproofing might be cement board (various names, eg hardiplank, villaboard, etc here in Australia)
Mine are in steel cases in shed separate from house but they are LiFePo4 not Li-ion so less risk there.
Those materials are very good but more expensive, in the NL DE and Pl i know for sure. dry wall will do the same for one hour if it is 1cm/half an inch thick.

Lifepo4 i would even stack them under my bed and go to sleep every night drunk without worrie's to not waking up....load one full...short circit him, shoot a bullet to him...hack with an ex if you want....with normal use and a bms on it(even the cheap ones) you have to do very difficult to let them catch a fire...put a stick of tnt in it or napalm or....i would even let my babies sleep on them....lifepo4 is very safe....sleep tight tonight.


Li ion on the other hand...well read carefully what i was typing and how offgrid was testing....(like most of us are testing minimum!!)

With best regards Igor,
My two cents(my 2 dollars or perhaps 2 coins)
Comments are always welcome, chime in if you think to know more, learn me please, correct me please
 

100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
So IMHO, fire management could be best focused on
a) containing a short intense burn (maybe with suitable venting, maybe allowing for a few "bursts of heat" as close cells burn)
b) separation to stop it spreading to adjacent packs/cells
c) not igniting nearby materials
All 3 to protect the rest of you ess!
Go with a...a simple cheap cap/lid/what ever you can get your hands on that prevents explosion/pressure building up and prevents the other to burn...
 

100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
But to all...ask your self why all those big powerwall owners have still there 100-200-300kwh powerwalls still running safely after 10 years....test the good the bad and the ugly.
And you dont hear those small quick powerwall owners youtubers anymore about there testing.....where are they anyway?!?!?!
Test properly please and be safe, enjoy and save money..EV, electric furnace, electric heating, light what ever, start small build it up, extend to even 500kwh, dont stop, even if you can put 1kwh a year in your wall.... but test your packs after a year, and wright everything down on your cells and pack before put them into use...better safe than sorry.
 

100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
I was talking in my work with a fire expert (for sure it was no "fresh from school boy"...)about li ion fire's
First off i made a mistake, i was stating the it was fn500 but apparently it is fm200.
Apparently the EU want to get rid of it.
So any alternatives?
Yes:
argonite
and
novec 1230

When i have more time i will give a proper reply after some "study".

With best regards
 

100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
Just a example of what i was referring about, to make it fire proof and a "bomb" hatch.
It is designed for a standing powerwall, oke it is down on his back on the working bench, but it is the idea..
20210912_160650.jpg
To give an impression with two "cells" with closed hedges...
Again this design is for a vertical powerwall...
20210912_160803.jpg
Oke a fire is breaking out, despite your fuses, the top dry wall piece will flap onto a other one(duck tape was all i had atm) and will thanks to gravity flap/flip back, the other ones will stay secure.
20210912_160917.jpg\
This is how simple it can be, tape for a hinge to protect the rest from 20 cells that are going a wall.
Yes to fill those gaps between the drywall, you will have to get a bag of gold or red band..
Btw any tape will do...
What do you care if one pack catches fire but the rest is still good and you only have to reinstall that one pack? incl some fire redundant chemicals....like novec....Yes i am busy with it, i will test some and let you know some results..I hope more people will test my idea...

Thanks for reading, with best regards Igor.
 

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100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
btw it is one layer it is 30 min fire proof just 1 cm thick drywall, to close those gaps, just use mp75 or what ever red/gold or what ever band of knauf...or simulair
 

OffGridInTheCity

Active member
Joined
Dec 15, 2018
Messages
1,738
I'm not quite understanding. What triggers the 'flap of drywall' to cover the pack in case of fire? OR is it just hanging there - and you're saying you can lift it up to access the pack? OR ....
 

100kwh-hunter

Member
Joined
Mar 2, 2019
Messages
760
I'm not quite understanding. What triggers the 'flap of drywall' to cover the pack in case of fire? OR is it just hanging there - and you're saying you can lift it up to access the pack? OR ....
If a pack will catch fire, it will blow/lift that "flap" up and the rest of the flaps are protecting the other cells/packs from the sparks and fire of that one

Edit:
And access for maintenance.
 
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Hanssing

New member
Joined
Jun 6, 2017
Messages
23
In general based on large industrial scale test, a NCA / NCM battery burns at 100h^-1 x its rated kWh-capacity
Ie. a 100kWh peaks at 10MW of burn power - if you have not seen these videos, they are worth watching.
If you get an LiFePo ignited it also burns but at roughly half the power compared to NCA, and its harder to ignite.

View: https://youtu.be/Fc-eJFIT-bo

View: https://youtu.be/aspF-GFOqHo

View: https://youtu.be/yIH9ED0j5dQ


Search for 'ESS fire test' on youtube and watch away - I cant guarantee that you will sleep well with 30kWh of dubious batteries in your basement......
 

Wolf

Active member
Joined
Sep 25, 2018
Messages
1,578
I cant guarantee that you will sleep well with 30kWh of dubious batteries in your basement......
Dubious..... definition
1: unsettled in opinion : DOUBTFUL I was dubious about the plan.
2: giving rise to uncertainty: such as
a: of doubtful promise or outcome, dubious plan
b: questionable or suspect as to true nature or quality the practice is of dubious legality.

@Hanssing While showing videos of purposefully set fires show the dangers of a lithium based battery fire I don't think any of us here plan to do that. I have several gasoline cans in my shed and I certainly wouldn't put heaters under them.
Now the word dubious comes in to play. I have been a staunch advocate of proper cell testing and that you should know every cell intimately.
It has a number as a name and all the testing results are attached to that name. In my case probably overkill but when I test my cells and record 16 parameters for each and every cell I get to know them. My whole data collection which includes everything (manufacturer, part number, build date, capacity, manufacturer IR, etc) is 28 datapoints. Some of these tests are repeated through time such as IR and Voltage and before final assembly the IR and Voltage is once again checked.
From salvage to final pack building I handle each and every battery at least 5 times. So as far as I am concerned there are no "dubious" cells/batteries in my build. As far as I am concerned the "salvaged" cells that make it through my testing have had the fire test so to speak. First they made it in the product that they were designed for without catching fire and then survived my stringent examination. I feel I run more non destructive tests on these cells than the manufacturer.
I cannot claim others have done the same as I, but if they do they can sleep quite good knowing that their cells are the best possible cells to put into a battery. I would not recommend putting them in your basement and the same goes with a gasoline can. There is always a certain risk you take living life. There is always a chance something might happen. According to the National Weather Service, a person has a 1-in-15,300 chance of getting struck by lightning in their lifetime. What are the chances that I will have a lithium fire? I don't know, but it is statistically improbable especially with monitoring your batteries and investigating any anomalies. Our choice to build our own batteries out of recycled items brings along a certain degree of responsibility and that is not to be taken lightly. Know your batteries.
PS
I sleep very well knowing I have close to 40kW of storage in my shed next to my house, knowing especially in the winter, if the power goes out I can flip a couple of switches and the lights are on again.
PPS Soon to be with an ATS so I don't have to get out of bed. :)
Wolf
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