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Fine dry sand as a fail-safe smothering agent for battery fires
#21
(03-04-2017, 07:41 AM)daromer Wrote: [Image: kzxXt4.jpg]

I was going to post the EXACT same design last night!!
My only addition would be to make the lid 2x the depth of battery box, to insure that it could completely fill the battery box.
The potential weakness I see is that a small hole could develop from a cell igniting that only allows a small trickle of sand through. I think it would probably be ok though because as any fire gets bigger, so would the hole, dropping more sand.
Last night I was working (in my mind) out a way to film this with a GoPro type camera in the box.
Also thinking of a way to provide access to batteries without lifting 100 pounds of sand...maybe drawer slides or sand box lid has legs with casters.
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#22
My concern with this design is that sand is quite heavy and over time, the integrity of the plastic may deteriate and start leaking sand into the battery compartment. I wonder if something other than sand could be used. Maybe baking soda or cornstarch? 

Has anyone considered a small halon fire extinguisher with a thermal button? If the extinguisher hose was directed into the battery box, it really wouldn't require very much halon gas to extinguish any flames.
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#23
(03-04-2017, 04:22 PM)JustJim Wrote: My concern with this design is that sand is quite heavy and over time, the integrity of the plastic may deteriate and start leaking sand into the battery compartment. I wonder if something other than sand could be used. Maybe baking soda or cornstarch? 

The only problem with baking soda or cornstarch is that it is very hygroscopic. So you would really need to make sure it was absolutely sealed from moisture. Otherwise, it wouldn't fall very far; or if it did, it'd be in clumps.    Sad Confused
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#24
Korishan: Yes but at same time you dont have to have them stadning.. The sand should shut the fire out even though not stadning. But if you do it standing it should put it out faster.

JustJim: Yes the design idea is perhaps not for long-term use Smile Its merely for testing.

APD: No i wouldnt say that the sand need to be bigger. It only need to cover gaps + 2cm above the batteries if you ask me. If you choose sand like blaster sand or something that easily fills all holes it should be fine. The amount of sand needed is something you need to calculate/test.
Dont forget that the appartment below do contain batteries that fill it up

The only thing i can think of is if the batteries blows up like a bomb. Then you need more sand to cover.

Did not have any time today to prepare it... And tonight/tomorrow morning im going to edit next video hmm...
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#25
(03-04-2017, 05:57 PM)daromer Wrote: APD: No i wouldnt say that the sand need to be bigger. It only need to cover gaps + 2cm above the batteries if you ask me. If you choose sand like blaster sand or something that easily fills all holes it should be fine.  The amount of sand needed is something you need to calculate/test.
Dont forget that the appartment below do contain batteries that fill it up

The only thing i can think of is if the batteries blows up like a bomb. Then you need more sand to cover.

Did not have any time today to prepare it... And tonight/tomorrow morning im going to edit next video hmm...

I have a sand blasting cabinet..... And the reason I suggest 2x volume of sand is because sand doesn't always fall. It gets stuck. If you've ever watched an hourglass, sometimes they just stop before all the sand has fallen.
The idea is to have a fail-safe system. We have no idea how large the hole will be when it forms, and every fire would be different.
Having more sand above means it will come down with more force and less likely to stop flowing.

I would much rather clean up sand than ashes!

Yeah it certainly needs testing.
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#26
One test is worth a thousand opinions.

That being said, my opinion is you dump enough sand on top of a burning lithium cell and it's not going to melt the Sahara desert.

I appreciate daromer taking his time to do independent testing and I look forward to his results. I've been having vehicle issues, driving a vintage car has its rewards but low maintenance isn't one of them.
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#27
Smile

Regarding blasting sand you are correct. Some of them doesn't fall well at all while others would lay flat.

I think i need to spend some more days thinking. Nevertheless my day is already jammed full
Follow me! >> YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcomming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#28
(02-22-2017, 01:51 AM)Elmo Wrote: I haven't really been considering stationary lithium batteries much until just lately but the idea came to me a few years ago when building ebike batteries to use fine dry sand held back by a plastic dam or  dams arranged so that  if the dam or dams melt the sand floods the battery space. I don't think I've seen the idea anywhere else and this seems like the ideal forum to share it on.

That's about it, choice of plastic, thickness and configuration of the dams, arrangement of the sand reservoir, the battery space and so on to be determined.

I've seen a small lithium battery fire, a big one could be catastrophic, I'm sure thinking about doing this with my upcoming setup.

I think this is a pretty good idea. 

You are not going to be able to smother a cell that has already lit off, but this will like keep the fire from spreading laterally to other battery banks, and perhaps downward.  Sand is a fairly good insulator, is a pretty good heat sink, and blocks the radiant heat.  You will have plumes of hot gasses bubbling up, but the gas will be cooled off pretty quickly as it flows through the sand.

I hope somebody tests this idea.  It has a lot of potential to be effective, simple, and cheap

(03-05-2017, 08:10 AM)daromer Wrote: Smile

Regarding blasting sand you are correct. Some of them doesn't fall well at all while others would lay flat.

I think i need to spend some more days thinking. Nevertheless my day is already jammed full

Beach sand, or sand from sand dunes, have rounded grains that makes the sand flow easily.

Sand blasting sand, or the sand for concrete, has sharp corners that prevents it from flowing well.
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#29
Oil? Ass insulation?
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#30
(07-30-2017, 09:07 PM)Joost2 Wrote: Oil? Ass insulation?

Oil is a good insulator, but also a good combustible, don't think this would stop any battery fire.

What about putting sand everywhere around of the batteries upfront?

The idea is some metal box with say 5 cm of sand on the bottom, then a battery pack, and 5 cm of sand on the sides and on top of the pack. The box should have a closed lid but not sealed so that fumes can get out to avoid building up pressure and making the box explode.

Would that be able to contain a fire and stop it from spreading?

Admittedly this would be a bit heavy for a mobile application but for a powerwall type of installation weight is less of a concern. Of course there would be sand everywhere between the batteries but that does not seem a big concern to me. Removing the sand when maintenance to the pack is required is a question of emptying the box over a bucket.
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