Fireworks from generic powertools pack.

[hermitdave]

Today I opened one of the two power tools battery pack I salvaged yesterday.. the Makita and a no name.. No name had YLE 18650E cells which aren't shrink wrapped rather wrapped in thick brown paper. Found 8 of 10 cells viable though whilst trying to undo spot welding, sparks flew and paper caught fire.. took it straight to garden.

After a few mins there, I cut the joining strips and realised that the first 2 cells got hot and vented.. blimey.. sealed those two cells with electrical tape.. need to create a discharger so that I can safely discharge cells like these..

Apparently 30A continuous and had lot of juice in them. In two minds about keeping them inside the house with other cells

 

[Korishan]

I would imagine they got shorted somehow. Maybe when "sparks flew" a piece of metal got stuck between the Pos raised portion and the Neg shell.

 

[hermitdave]

I would imagine they got shorted somehow. Maybe when "sparks flew" a piece of metal got stuck between the Pos raised portion and the Neg shell.

The nickel coated copper sheet was large and not far from negative side.. not sure was the ring is made of ., suspect paper which might have burned away

 

[Korishan]

Yeah, they are usually just a felt paper. Doesn't take much to light them. But, a spark alone won't do it. Must be sustained heat. So, if you were prying, it's possible a piece of strip stuck through the ring and made contact with the shell. At this point, because of the sparks, you yanked the prying device out but didn't notice there was still metal touching metal.

Just guessing, of course

Glad it didn't blow up, tho. That's partly why we don't do "prying" like that on the cells. Most usually just snip and then pry "away" from the cell. Some roll, some just pull away. Others just snip as close as possible to the cell and leave the remaining piece in place.

 

[hermitdave]

Yeah, they are usually just a felt paper. Doesn't take much to light them. But, a spark alone won't do it. Must be sustained heat. So, if you were prying, it's possible a piece of strip stuck through the ring and made contact with the shell. At this point, because of the sparks, you yanked the prying device out but didn't notice there was still metal touching metal.

Just guessing, of course

Glad it didn't blow up, tho. That's partly why we don't do "prying" like that on the cells. Most usually just snip and then pry "away" from the cell. Some roll, some just pull away. Others just snip as close as possible to the cell and leave the remaining piece in place.

Yes need to start splitting the pairs before doing anything else.

 

[hbpowerwall]

I keep bucket of salt water next to me when i'm shucking cells

 

[hermitdave]

I keep bucket of salt water next to me when i'm shucking cells

I shall put the cells that vented in a bowl of salt water when I get home.

 

[Korishan]

I keep bucket of salt water next to me when i'm shucking cells

Hahaha, I got the thrashings for suggestion such a thing last week.

I shall put the cells that vented in a bowl of salt water when I get home.

No, no, no. A bucket. Not a bowl. If those things start jetting around, you want them contained

 

[hermitdave]

I keep bucket of salt water next to me when i'm shucking cells

Hahaha, I got the thrashings for suggestion such a thing last week.

I shall put the cells that vented in a bowl of salt water when I get home.

No, no, no. A bucket. Not a bowl. If those things start jetting around, you want them contained

I thought i read something along those lines.. just couldn't find it.. oh well.. i have it in a bowl.. prepped a bucket..

Lot of bubbles.. not sure if i should dunk the bowl in the bucket

 

[Korishan]

bubbles are due to electrolysis. This is what's really pulling the voltage down on the cells. And it'll pull them all the way down, too.

Salt is generally bad to metal. But if you are going to be tossing the cells anyways, it doesn't matter.

I'd put the cells in the bucket with the buck 1/2 full of salt water. Forget the cup altogether.

btw, you don't need much salt, about 2Tbs or so in the bucket. You could also use baking soda.

 

[hermitdave]

So the salt is acting as a catalyst. We have H2 + O2 being bubbled.. nice
Done

 

[BlueSwordM]

Yeah never do this inside.

Unless you want to end up like my plastic bottle back in 6th grade.

 

[Korishan]

Oh yeah, the other is you have explosive gases. Another reason to do the bucket and not the cup. They are diffused more. You don't want a spark near the open end. About the most you'll get is a ringing in the ears and maybe some singed hairs. Unless enough has built up (in a room, for example). Outside is plenty of breeze.

Yeah, a plastic bottle would become mince meat relatively easily

 

[BlueSwordM]

Yep. That was an experiment in science class that I did.

I put some veggies+fruit cuts, closed the bottle for about 1 month, then opened it up with the approval of my science teacher, and then she lit a it with a lighter.

What happened afterwards was an extremely loud bang

Methane is no joke. Hydrogen is even worse. Also, the problem with lithium ion cells is that their rapid chemical degradation under heat is a self-sustaining reaction because of the presence of dioxygen in the reaction, which is rather problematic

 

[Korishan]

True. Only if the cell gets hot enough to break down the components make the O2 release. Good thing the water cools it down rather quickly

Sooo, i suppose don't do this throw it in a bucket trick with boiling water

 

[hermitdave]

True. Only if the cell gets hot enough to break down the components make the O2 release. Good thing the water cools it down rather quickly

Sooo, i suppose don't do this throw it in a bucket trick with boiling water

In this instance the actual contents of electrolysis are small in volume unless you chuck in a whole lot of cells. H2 makes its escape rather quickly. Saw some cells content diffusion as well.. will get a large v resistor tomorrow.. got a few 17670 cells to discharge and throw.