I'm working with my department's fire marshal and she said 60ft, I'm assuming that's good? I'm guessing she's more worried about the fragments shooting around.
um... she sounds... idk how to say it. But an arbitrary 60ft doesn't account for wind or elevation. I think a video demonstration might be better for the sake of health and liability.
just be careful. you won't always get to control or predict how it moves. I spent a long time in front of fires to know that it can usually hit all 360 degrees eventually given enough time, or sometimes suddenly.
I'm gonna try setting up a pneumatic cylinder to pierce a phone or tablet battery to demonstrate tampering and what that reaction would look like, charged and dead
The way I did it…for testing and educational purposes ONLY:
I used a clamp to anchor an 18650 lithium ion cell to the ground in case it went flying.
Then, I took an axe and hit the cell after fully charging it.
But, don’t hit so hard that it cuts all the way through! Basically make a big cut in the side about halfway through.
Result: Thermal runaway
Hope that helps!
Shorting shouldn't do anything if it is a decent cylindrical cell. The PTC will choke off the current.
What cells were you thinking of? Many of the "AA sized" li-ions out there are actually LiFePO4 for solar lights and they are nearly impossible to catch fire.
I was looking to modify the battery packs and take the PTC and any other safety features out. And interesting, good to know. Would those be clearly labeled as Lithium iron phosphate or could I accidentally buy those? For reference, I'm just looking to recreate a FSRI or UL demonstration of the ignition of a battery pack. My initial thought was to build my own pack using individual cells but now I'm starting to think it'll be easier to buy and modify a pack.
As part of the class I'll also tamper with a pouch-style phone or tablet battery and pierce it. Just to observe the off gassing. Most fire calls we go on involving lithium ion batteries are because of someone tampering or cutting these types of cells.
You can't really take the PTC out. Its not part of the pack. Its built into cylindrical cells. You'd have to un-crimp the cell and disassemble the top and re-crimp it. All in an oxygen-free environment or you risk the battery burning up during the modification.
It is possible to buy cells without the PTC but they are not easy to find. Tesla is infamous for using cells without PTCs.
Yes LFP cells are clearly labeled.
Pouch cells are *very* easy to set off. There is a video floating around of someone who started a fire by biting a pouch cell.
Wow that you very much, that's good to know. Do you know how I would even begin looking for cells without? Or if I use a battery pack (maybe a big 12v) made of multiple cylindrical cells, would it only have 1 PTC for the whole pack instead of in each individual cell?
Asking the same question different ways won't get you a different answer. You'll just get the same answers back.
Like I said: Tesla cells usually don't have them. Don't want a PTC? Try to find some recovered Tesla cells.
Like I said: its a cell-level thing. You won't find a pack with a PTC instead. The pack should have a thermister for the BMS but that is completely different.
>Pouch cells are very easy to set off. There is a video floating around of someone who started a fire by biting a pouch cell.
Our dog did that one Christmas day: got ahold of a small pouch cell from a new drone, pulled it off the charger and carried it to her dog bed to chew on. We found out when the top of the bed caught on fire.
Wrong. Datasheets for 18650s have a safety testing section. Part of that section is that the cell can withstand a continuous direct short without fire or explosion.
If it is a namebrand cell then shorting is "safe."
What about 18650s that were extracted from battery packs? such as laptops and power tools? Could they not have added likelihood of going ablaze since they were never intended for individual use outside of their housing?
There's plenty of fake amazon milwaukee packs that might have less than to-standard batteries inside.
Actually, while we're on that subject, what about lithium packs? like those rolled-up ones found in non standard shapes and sizes used in children's toys and vibrators and such? Even better, old counterfeit samsung galaxy S3 and older battery packs. those should do it. I've had plenty that poofed up on me in the past. classic sign of having an affinity to fire starting.
The original testing for thermal runaway was digging a big hole and wrapping the pack in ni chrome wire, and just dumping current into it until it caught on fire. Might override the safety caps on modern cells, might not. Have blown a few cylindrical cells myself with thermal runaway but the safety cap stopped any further issues. (Was not intentionally setting them off btw, old cells can be finicky)
Depends on the resistance of the ni chrome and the power supply. There should be some wiki articles on how to get an approximate temperature based on power and resistance. For reference, thermal runaway happens somewhere near 150F so I’d calculate to get a 450 F temp just to be overkill
Your best bet is to heat it up till it goes. You can also control how spicy the event is by how much you charge it before setting it off (50% usually has good flames without being too sketchy). I wouldn’t overcharge unless you’re set up to contain the shrapnel
Fully charge a pouch cell. A single 1000mAh cell should be enough. Drill a hole in a board and place a nail through hole. Place board over battery. wearing a face shield, give that nail a god solid hit and step back
Or drop a cell onto a hot plate. You should have plenty of time to step back.
shallow saltwater in a robust and fireproof contaner. shallower than the battery is wide, but enough to cause the short, not too much to make heating difficult. The thing with those news story worthy tesla fires and such is that they're tons and tons of 21700s. sheer scale creates the fire. one cell is kinda hard. and it won't look spectacular even as its burning up.
Crowbar to the side? I've had plenty of cells start getting hot and then burn just from prying them out of packs where they were hot glued together. If you watch some YouTube videos of dissecting 18650 cells, you can see they are a lot of concentric layers. So a good solid dent is going to short across all those internally.
I can show ya pics of my burns after my vape mod blew up in my pocket from a thermal runaway... Just get an efest and leave it on the charger it'll over charge and runaway... Twas what mine did.
Nail? steak knife? Vise?
Note that the fumes from the battery are highly toxic.
I'm working with my department's fire marshal and she said 60ft, I'm assuming that's good? I'm guessing she's more worried about the fragments shooting around.
um... she sounds... idk how to say it. But an arbitrary 60ft doesn't account for wind or elevation. I think a video demonstration might be better for the sake of health and liability.
Obviously we aren't going to stand down wind
just be careful. you won't always get to control or predict how it moves. I spent a long time in front of fires to know that it can usually hit all 360 degrees eventually given enough time, or sometimes suddenly.
[удалено]
I'm gonna try setting up a pneumatic cylinder to pierce a phone or tablet battery to demonstrate tampering and what that reaction would look like, charged and dead
You have the video? I'm interested in the results.
Vice, nailgun, remote trigger and a sheet of lexan? I watched a lot of Mythbusters growing up.
The way I did it…for testing and educational purposes ONLY: I used a clamp to anchor an 18650 lithium ion cell to the ground in case it went flying. Then, I took an axe and hit the cell after fully charging it. But, don’t hit so hard that it cuts all the way through! Basically make a big cut in the side about halfway through. Result: Thermal runaway Hope that helps!
Shorting shouldn't do anything if it is a decent cylindrical cell. The PTC will choke off the current. What cells were you thinking of? Many of the "AA sized" li-ions out there are actually LiFePO4 for solar lights and they are nearly impossible to catch fire.
I was looking to modify the battery packs and take the PTC and any other safety features out. And interesting, good to know. Would those be clearly labeled as Lithium iron phosphate or could I accidentally buy those? For reference, I'm just looking to recreate a FSRI or UL demonstration of the ignition of a battery pack. My initial thought was to build my own pack using individual cells but now I'm starting to think it'll be easier to buy and modify a pack. As part of the class I'll also tamper with a pouch-style phone or tablet battery and pierce it. Just to observe the off gassing. Most fire calls we go on involving lithium ion batteries are because of someone tampering or cutting these types of cells.
You can't really take the PTC out. Its not part of the pack. Its built into cylindrical cells. You'd have to un-crimp the cell and disassemble the top and re-crimp it. All in an oxygen-free environment or you risk the battery burning up during the modification. It is possible to buy cells without the PTC but they are not easy to find. Tesla is infamous for using cells without PTCs. Yes LFP cells are clearly labeled. Pouch cells are *very* easy to set off. There is a video floating around of someone who started a fire by biting a pouch cell.
Wow that you very much, that's good to know. Do you know how I would even begin looking for cells without? Or if I use a battery pack (maybe a big 12v) made of multiple cylindrical cells, would it only have 1 PTC for the whole pack instead of in each individual cell?
Asking the same question different ways won't get you a different answer. You'll just get the same answers back. Like I said: Tesla cells usually don't have them. Don't want a PTC? Try to find some recovered Tesla cells. Like I said: its a cell-level thing. You won't find a pack with a PTC instead. The pack should have a thermister for the BMS but that is completely different.
You just said above that Teslas do^ thanks anyway though
>Pouch cells are very easy to set off. There is a video floating around of someone who started a fire by biting a pouch cell. Our dog did that one Christmas day: got ahold of a small pouch cell from a new drone, pulled it off the charger and carried it to her dog bed to chew on. We found out when the top of the bed caught on fire.
your good ole 18650 from anything is gonna do it. fully charge and then short. it's easy peazy.
Wrong. Datasheets for 18650s have a safety testing section. Part of that section is that the cell can withstand a continuous direct short without fire or explosion. If it is a namebrand cell then shorting is "safe."
What about 18650s that were extracted from battery packs? such as laptops and power tools? Could they not have added likelihood of going ablaze since they were never intended for individual use outside of their housing? There's plenty of fake amazon milwaukee packs that might have less than to-standard batteries inside. Actually, while we're on that subject, what about lithium packs? like those rolled-up ones found in non standard shapes and sizes used in children's toys and vibrators and such? Even better, old counterfeit samsung galaxy S3 and older battery packs. those should do it. I've had plenty that poofed up on me in the past. classic sign of having an affinity to fire starting.
Why not just create an Infinity Circuit? that will make it runaway almost instantly.
The original testing for thermal runaway was digging a big hole and wrapping the pack in ni chrome wire, and just dumping current into it until it caught on fire. Might override the safety caps on modern cells, might not. Have blown a few cylindrical cells myself with thermal runaway but the safety cap stopped any further issues. (Was not intentionally setting them off btw, old cells can be finicky)
What did you use for the current?
Depends on the resistance of the ni chrome and the power supply. There should be some wiki articles on how to get an approximate temperature based on power and resistance. For reference, thermal runaway happens somewhere near 150F so I’d calculate to get a 450 F temp just to be overkill
https://www.youtube.com/watch?v=qJ8BzvbeRXQ
Your best bet is to heat it up till it goes. You can also control how spicy the event is by how much you charge it before setting it off (50% usually has good flames without being too sketchy). I wouldn’t overcharge unless you’re set up to contain the shrapnel
Fully charge a pouch cell. A single 1000mAh cell should be enough. Drill a hole in a board and place a nail through hole. Place board over battery. wearing a face shield, give that nail a god solid hit and step back Or drop a cell onto a hot plate. You should have plenty of time to step back.
shallow saltwater in a robust and fireproof contaner. shallower than the battery is wide, but enough to cause the short, not too much to make heating difficult. The thing with those news story worthy tesla fires and such is that they're tons and tons of 21700s. sheer scale creates the fire. one cell is kinda hard. and it won't look spectacular even as its burning up.
A: Put it in a Tesla.
Crowbar to the side? I've had plenty of cells start getting hot and then burn just from prying them out of packs where they were hot glued together. If you watch some YouTube videos of dissecting 18650 cells, you can see they are a lot of concentric layers. So a good solid dent is going to short across all those internally.
I can show ya pics of my burns after my vape mod blew up in my pocket from a thermal runaway... Just get an efest and leave it on the charger it'll over charge and runaway... Twas what mine did.