This video is just a demonstration of how salvaged lithium cells can be put to good use for either decorative or functional lighting with minimum circuitry.
It also shows a way to test whether a small cell has active protection.
Note that the short-circuit test resistors get hot quickly if there is no protection circuitry or the cell is rated for very high current. They should only be applied very briefly.

It's quite a neat way to add a bit of extra self-contained decorative lighting to your workshop or home that will stay lit in the event of power failure. If the battery is made waterproof with a plastic bag or other cover then this technique can also be used to add lighting to small plants/trees outdoors.

As always with lithium cells, make sure they are protected from physical damage and don't show signs of previous damage like significant sharp dents or puncturing.
The best way to render a lithium cell safe is to discharge it to 3V or less when there is little energy left to cause fiery incidents.
The charging modules shown are intended for traditional lithium ion cells with an upper voltage of around 4.2V (average voltage 3.7V) and are not suitable for LiFePO4 type cells that have an upper voltage of 3.6V (average voltage 3.3V) unless they have their own protection circuitry to cut off the charge at full capacity.

The lithium content calculation was based on roughly 0.3g of lithium per 1000mAh original capacity of a rechargeable cell. An equivalent non-rechargeable cell uses more lithium than one that can be recharged hundreds of times, but crams about four times the capacity in the same space.

In hindsight, maybe the title of this video should be "Inventing ways to use my stash of lithium cells."

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