Short_Shot
Solar Addict
- Joined
- Jul 13, 2021
- Messages
- 1,823
Also a valid point.Exploded cell will leak enough electrolytes to make distilled water conductive.
Also a valid point.Exploded cell will leak enough electrolytes to make distilled water conductive.
You can run 150 thousand volts through a chain of toddlers with nothing more than their hair standing on end too, under the right circumstances of course.
I've eaten 480 hand to hand once and lived. Not sure how. I suspect the cabinet paint saved me, offering up just a bit more resistance.It's very hard to be killed by 120V AC if you skin is dry. I was many time zapped by 220V and couple times I was stupid enough to accidentally touch one 220V wire by one hand and another wire by another hand. Still alive
There is some misunderstanding of basic V=IR here.I am a little late to this love fest but I want to point out one thing.... at 54.4 volts my 20kw (400 A/h) battery bank give me a shock through the skin of my hands if I present a ground to it. I found that out when I was building it... something my AGM 600 A/H battery bank never did. the lithium batteries being able to dump their current at a much higher rate makes and prior data about DC volts vs amps and danger something that needs to be looked at again. It literally shocked some sense into me.
While it was only a tingling feeling (which my dumb ass (due to surprise) turned around and tested by touching the terminals and it was enough to make my finger twitch and jerk off the terminal) so we are in the realm of danger.
I had the discussion with someone here about DC power, danger etc. and at that time I was probably kind of ambivalent about it, well I was wrong... it can zap you, at least with LiFePo4 batteries.
1. As already mentioned you would need to devise some other mechanism to trigger the water dousing.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,
1. 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.
2. 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.
LOL..Mineral oil is not conductive
Heat I would imagine. Lithium cells can get pretty warm and thermal runaway is an issue. Insulating them would be a big problem.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.
My 18650 cells average charge/discharge is <200ma/cell and they don't get warm at all.Heat I would imagine. Lithium cells can get pretty warm and thermal runaway is an issue. Insulating them would be a big problem.
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.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.
It's heat.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.
In a thermal event water is your friend....Oh gawd please don't use water. Lithium + water = chemical reaction + hydrogen gas. You don't really want to mix the two.
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.In a thermal event water is your friend....
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?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.
Water in a fire cuts oxygenAny 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.
welcome to the forumI 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?
Thank you. Long time lurker, who’s getting serious now. I’d like to thank the forum for the infinite wisdom.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