This light is a direct descendant of one of the earliest styles of USB rechargeable LED keychain lights.

I took one of these apart 10 years ago and was hoping the circuitry would have been upgraded with a proper charge control chip, but instead they've made a vague attempt at a crude charger with a voltage divider and diode, and then botched it. This means that if left charging for a very long time there is a risk of the small lithium cell inside being charged to significantly more than 4.2V.

The lithium cell has no protection PCB. Sometimes I wonder if the small size of the lithium cells in some products is used as justification for disregarding proper charging control in the belief that they're too small to be dangerous.

I don't really recommend buying this, as it is nowhere near as good as the more modern multi-mode keychain lights. But here's a non affiliate link if you have a use for the case:-
https://www.aliexpress.com/item/1005009376819736.html




If you enjoy my videos and would like to support me with a dollar or two for coffee, cookies and gadgets to take apart, you can do so by supporting me on Patreon. I release videos without adverts for critique and feedback on Patreon as soon as they have been made. I also release Patreon-only backstage videos when I'm working on shows.

https://www.patreon.com/bigclive

Alternatively, for a single coffee contribution you can use PayPal:-
https://www.paypal.com/paypalme/bigclive


#ElectronicsCreators
...
https://www.youtube.com/watch?v=HvX4zRKSvrk