Containing a battery pack meltdown.

[Bluedog225]

If sand is non-conductive, why not cover the cells with sand after build? That is, no need for a fancy release system, just embed the whole deal in sand from the outset. It would have a dampening effect on the whole arrangement.

 

[Short_Shot]

If sand is non-conductive, why not cover the cells with sand after build? That is, no need for a fancy release system, just embed the whole deal in sand from the outset. It would have a dampening effect on the whole arrangement.

Heat I would imagine. Lithium cells can get pretty warm and thermal runaway is an issue. Insulating them would be a big problem.

 

[OffGridInTheCity]

Heat I would imagine. Lithium cells can get pretty warm and thermal runaway is an issue. Insulating them would be a big problem.

My 18650 cells average charge/discharge is <200ma/cell and they don't get warm at all.

If sand is non-conductive, why not cover the cells with sand after build? That is, no need for a fancy release system, just embed the whole deal in sand from the outset. It would have a dampening effect on the whole arrangement.

This might be one of those ideas either so obviously wrong ( because no one has done it that I know of ) OR maybe so brilliant because its outside the box for sure.

Thinking out loud a bit... Sand would block access to the cells... and I do occasionally need to do maintenance on my DIY 18650 packs. For and EV the weight would be a no go. The sand might gather moisture? and result in some rust or conductivity?. Maybe something sand like but not sand? - interesting idea.

 

[Short_Shot]

My 18650 cells average charge/discharge is <200ma/cell and they don't get warm at all.


This might be one of those ideas either so obviously wrong ( because no one has done it that I know of ) OR maybe so brilliant because its outside the box for sure.

Thinking out load a bit... Sand would block access to the cells... and I do occasionally need to do maintenance on my DIY 18650 packs. For and EV the weight would be a no go. The sand might gather moisture? and result in some rust or conductivity?. Maybe something sand like but not sand? - interesting idea.

It's heat.

Yours don't get hot maybe but with high c rates they do, can, and will runaway.

Moisture wouldn't be an issue in a dry environment but might in a damp basement.

 

[thegoogler]

Oh gawd please don't use water. Lithium + water = chemical reaction + hydrogen gas. You don't really want to mix the two.

dropping lithium into water - Google Search

www.google.com

 

[newbostonconst]

Oh gawd please don't use water. Lithium + water = chemical reaction + hydrogen gas. You don't really want to mix the two.

dropping lithium into water - Google Search

www.google.com

In a thermal event water is your friend....

 

[thegoogler]

In a thermal event water is your friend....

Sort of. Water is your friend if you have a lot of it available to drown the pack and dilute the lithium-to-water ratio. To the OPs original question I wouldn't try to drown a lithium battery fire with a (melting plastic) gallon of water. Water will cool the pack but will react to lithium so you need enough water to counteract that reaction. You also need to vent the gas or you risk that exploding.

Personally if concerned about a meltdown scenario I'd look for a way to monitor and alert you as soon as the temp spikes and then a way to safely control it

• bags of sand would be cheap. If you're suspending them above the battery use plastic bags, which will melt easily but are otherwise sturdy. That's apparently how some self-contained charging stations work.
• fire suppression designed to deal with lithium chemistries would be better.

That said according to the article below in LFP batteries (not LI) the amount of lithium is fairly low and water probably will work OK, but a dry or CO2 (or a class D even better) extinguisher would be preferable. This short article below is absolutely worth a read for all DIYers

http://robotsforroboticists.com/lithium-ion-battery-safety/

 

[Flygaff]

If sand is non-conductive, why not cover the cells with sand after build? That is, no need for a fancy release system, just embed the whole deal in sand from the outset. It would have a dampening effect on the whole arrangement.

I saw the other day an ad that was using tiny glass balls to put out battery fires, seemed expensive/heavy. However what they had to compare it with was perlite. I’m considering encapsulating my packs with perlite, does anyone an issue with that?

 

[gotbeans]

Any thoughts on something like this:

15kwh 14s 18650 battery pack,
Put it at the bottom of a 55 gallon steel drum
put a couple 32 packs of water bottles inside the barrel above the batteries.
Cut a hole in the lid and install a cooling fan.

If all the other safety measures failed for some reason,
Battery catches on fire, melts the plastic water bottles and gets doused in water.

In theory all the energy goes toward making steam instead of burning down my garage.

Does burning an 18650 release more energy than fully discharging it?

15kwh is 54 mega joules, or enough energy to boil only about 5 liters of water.

And if you are wondering about just the steel barrel without the water,
It would only take about 2.5 mega joules to melt the lid on a steel drum.

Water in a fire cuts oxygen
the 4 in LiFePO4 is next to oxygen.. which means there's 4 of them
the chemistry can burn under water.

I recommend just building your batteries inside of a concrete box (which is what I do) obviously have it moveable / able to be serviced
sand also will work just by blocking the fire from going anywhere, it'll still burn until it decides it's done.

There's a reason firefighters just make sure nobody goes near when a car catches fire and then stand around and wait.

I saw the other day an ad that was using tiny glass balls to put out battery fires, seemed expensive/heavy. However what they had to compare it with was perlite. I’m considering encapsulating my packs with perlite, does anyone an issue with that?

welcome to the forum
perlite should work, interesting idea

 

[Flygaff]

Water in a fire cuts oxygen
the 4 in LiFePO4 is next to oxygen.. which means there's 4 of them
the chemistry can burn under water.

I recommend just building your batteries inside of a concrete box (which is what I do) obviously have it moveable / able to be serviced
sand also will work just by blocking the fire from going anywhere, it'll still burn until it decides it's done.

There's a reason firefighters just make sure nobody goes near when a car catches fire and then stand around and wait.


welcome to the forum
perlite should work, interesting idea

Thank you. Long time lurker, who’s getting serious now. I’d like to thank the forum for the infinite wisdom.

Here’s the video, the product they are attempting to sell looks very similar to perlite.

 

[400bird]

Water in a fire cuts oxygen
the 4 in LiFePO4 is next to oxygen.. which means there's 4 of them
the chemistry can burn under water.

In this case, the water is to cool down the area so the neighboring cells are less likely to catch fire.
You can't stop the already on fire cells, but you can try to stop it from spreading.

I'm pretty sure cooling and depriving oxygen is purpose of water on most fires, but I'm not a firefighter.

 

[gotbeans]

Thank you. Long time lurker, who’s getting serious now. I’d like to thank the forum for the infinite wisdom.

Here’s the video, the product they are attempting to sell looks very similar to perlite.

The first one they dump I was gonna say that's totally vermiculite (and then I saw it literally says that on the bottle LOL)
it's better for holding moisture.
Perlite better for adding air to your dirt..

Their stuff does look like perlite, there are tons of better videos on it.
It's some glass stuff but in the end is probably pretty similar to perlite in the ways it puts out fire.

I doubt their perfect circle shape does that much of a difference, that's the only main difference I see vs perlite