Recycled Lithium 18650 - DIY power banks

[TerraHertz]

As battery energy density increases, so do the consequences of damage. 18650s, even banks of them, probably have a fairly low 'blast radius'. A larger blast radius is illustrated in this online comic. Just for fun:

  https://tapas.io/episode/1009477

You'd have to go back a few strips for the context. To at least here: https://tapas.io/episode/954357
Anyway, the electric hover cycle was damaged, and a while later blew up.

[Inverted18650]

probably have a fairly low 'blast radius'.

They "vent" and then act like small jet engines. I've never had one catastrophically fail on its own, but I did force a handful to fail for testing. They all flew around the plexi-glass box with the majority of the energy staying contained inside the cylinder and blowing out of one end.

[DenzilPenberthy]

Hmm, the cute animated intro shows a mix of batteries (different colors), but his power wall uses a large number of all-identical cells. So I don't think those are recycled.

He saves the purple ones and puts them on the outside so they look nice. They are recycled.

[paulca]

Also, my experience with old crusty laptops is that their batteries are completely shot. "Hooray, I have some 18650s with 400 mAh capacity! Winner!"

Actually laptops use rubbish BMSes.  These are incapable of balancing the cells properly.  So when one cell gets tired the imbalance slowly increases until the BMS cut offs give you about 10% battery capacity.

When you dismantle them you very often find that one cell pair is completely broken and the others are fine.

I wouldn't through out 18650s or any lithium batteries, even when completely useless.  The copper sheets in them are steadily rising in price year on year.

[KD0CAC John]

What's with all the chicken littles [ false paranoid worry warts ] .
Sure anything can go bad , if we all used the lowest common denominator thinking , we would do nothing .
Life is hazardous - ban it
I am just starting to collect used 18650's , 100's of them , mostly from laptops .
Depending but with most all packs being given to me because they no longer work , I disassemble , go through a series of tests , then at least a couple of charge discharge cycles , then find the milli amp hour rating , and classify them to about 10% of each other to make packs for future use .
With many out there doing the same , and making large home power supplies , like DIY Tesla power walls .
Like any other tech. you need to learn to do correctly , all kinds of nit-wits do stupid stuff .
To think / say and or use nit-wits as an example and never do anything that is not store bought , well - that just lets there be more for me  

[paulca]

Not sure if it's been mentioned, but you will find a lot of power walls interconnect the cells with 5A fuse wire.  In theory no single cell should deliver or have more than 5A flowing across it, so the fuse wire protects things from catastrophic melt down.  Of course the whole wall itself can delivery many times 5A.