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The most interesting things about this rechargeable light are its physical construction and very low component count.

The charging circuitry is similar to some solar lights and shavers I've looked at, so I'm guessing it may be actual dedicated charge circuitry built into a microcontroller, or perhaps just implemented in software.

https://youtu.be/H3wuflr-RFY

Files

eBay 98kW LED flashlight (slightly exaggerated) with schematic

Another of the many products on eBay where the sellers try to outdo each other with very ambitious ratings. Far too ambitious in this instance. The construction of the light is interesting because it has been optimised for fast manufacture. The circuitry is ultra minimalist, including the USB charging circuitry that doesn't inspire a lot of confidence. Don't leave one of these on continuous charge. Other than that, it does work, the beam focus feature works well and it doesn't have too many useless modes. The cell capacity tests at a very ungenerous 160mAh and the charge circuit does keep trickle charging the cell after the LED has stopped flashing, and when I monitored it for a while it peaked at a slightly uncomfortable 4.27V then suddenly settled back down to 4.21V, making me wonder if it had energised the load briefly when I wasn't there as part of its charge control. If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- https://www.bigclive.com/coffee.htm This also keeps the channel independent of YouTube's algorithm quirks, allowing it to be a bit more dangerous and naughty. #ElectronicsCreators

Comments

Andreas Schuderer

Isn’t a lot of faith put into the uC here regarding the charging circuit? I‘m an electronics beginner, but the pullup R in the base of the transistor in emitter follower configuration would mean athat if the uC is dead, we get USB‘s full 5V on the lithium ion battery. I am probably overlooking something but would be interested in whether that’s true or not

bigclive

Yes. I'm not a fan of microcontrollers controlling charging. I'm not sure if the chip has a fixed shunt device on that pin to cap base voltage relevant to the lithium cell voltage present at its emitter.

John Harrison

I was in Spain last week and saw this green lamp have a quick look how simple it was made it was 5 euro - the first few images at the top. Ignore the frozen snack in the freezer https://photos.app.goo.gl/HNrlzJlEWwOdld0h2

bigclive

That's a very retro tungsten-style. I bet it flickers in use due to contact issues.