Watch what happens when you shoot a lithium-ion battery with a nail gun

Originally published at: Watch what happens when you shoot a lithium-ion battery with a nail gun | Boing Boing

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I should put my bike battery out on the balcony.

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yeah, they say in the video “you won’t run into a battery like this” - but ebikes, scooters, batteries for home solar, electric cars… all seem like they have batteries at least that big

( and apparently teslas run into things all the time :cat2: )

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Not an expert, but as I understand it lithium ignites on contact with air. Expose it to air, it ignites at room temperature. You can only stop the fire by taking away the air. The fire extinguishers are used to stop the furniture and buildings from burning, not the battery.

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Lithium-ion batteries are at highest risk of fire during charging. Once charged, they’re stable (unless something happens to them.)

They are safest when nearly empty, but never drain them completely or you will damage them. Chemically the ideal long term storage charge level is 50-60% (roughly half full is fine.)

Never pierce them, of course. Also, don’t dead short them. Those actions can lead directly to fire.

They are very temperature sensitive. They are safe between -4F and 140F (-20C - 60C), but they should be stored between 32F and 104F (0-40C), as they develop chemical damage outside of that range. And they should be between 40-114F (5-45C) during charging, with charging current kept lower at the lower temperatures.

The ideal temperature for lithium ion batteries is 59F (15C).

For longest battery life, slow charging is better than rapid charging. For overnight phone charging, if you have a choice between a charging cable and a wireless charger, the wireless will almost always be the better choice.

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To add onto that - going below 32F is less damaging than going above 104F - you really should never leave a lithium-ion battery in a hot car - while the battery is (usually) safe in a ‘won’t blow up’ kind of way - you will cause the battery to boil off some of it’s capacity forever - and that’s the best case scenario.

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Watch what happens when you shoot a lithium-ion battery with a nail gun

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I wouldn’t have thought discharging the battery would make such a big difference in reactivity.

There’s one thing I’ve never been entirely clear on: if a battery has already gone pillow-shaped, is there significant danger in puncturing it? Obviously you wouldn’t want to take a deep breath of the vapors inside and you probably wouldn’t want to wave it around an open flame (kind of like most things), but it’s not likely to explode at that point, is it?

There are various videos, of course.

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Puncturing the cell can pierce the membrane separating the anode from the cathode. This can cause a short circuit in the presence of the flammable electrolyte. If the cell has a low charge it may not have the energy to spark or heat the short circuit to the flash point of the electrolyte.

But once a cell starts on fire, the membrane will melt and fail throughout the cell, which will allow more areas of the anode and cathode to short circuit, which could speed up the amount/area of flashpoints. And the more places it ignites simultaneously, the hotter and faster it will burn.

The main risk I’ve seen with “spicy pillows” is that they force the package outward into places in the case where it wasn’t designed to go. I had one in a badly designed clock pushing hard against some soldered pins on the back of a PCB, leaving two rows of little spiky indentations in the pillow. It was a cheap no-name cell, so I have no idea if the cell even had a pressure release vent built in. Had the battery pressure increased, or if it was forced around a sharp corner of a PCB, or along a sharp slit, it might have cut the envelope, releasing the gas and electrolyte, possibly damaging the membrane and/or starting a fire.

One of my Dell laptops seems to have been designed for battery failure, as the spicy pillows forced the keyboard to bulge up and out, instead of squeezing the battery into higher pressures in places it shouldn’t go. While it wrecked the laptop’s keyboard, it did not start my house on fire. So I consider that a safety design win.

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