These seem very common on sites like AliExpress, and are distinctive for their use of a traditional cylindrical lithium cell. In keeping with the rest of the design, they have used a really cheap and low capacity 14500 cell that clocked in at just 200mAh, so a valid upgrade could be putting in a proper 800mAh one. Note that the leads are soldered directly to the cell, which is less ideal with high capacity ones stuffed to the brim with chemistry. If using a high capacity cell a tabbed cell may be a good choice.

This flashlight / torch may be ideal for a street-lithium upgrade with a 500mAh cell salvaged from a "disposable" vapour device.

It should be straightforward to swap in an LED with a colour of your choice, but only gallium nitride style LEDs as a pure red one will have a lower voltage and may pass too much current.

The circuitry is ultra minimal. The microcontroller pin impedance is limiting the current to the side LEDs and the transistor for the main spotlight LED is acting as a current limiter too.

The USB-C charge circuitry lacks the two simple resistors needed to signal to a smart charger that it is a load, so you may have to use a traditional USB-A to USB-C lead to charge the unit.

The charge circuitry is very similar to that found in many cheap products like shavers and solar lights, and uses a simple transistor and base resistor arrangement to allow the microcontroller to monitor and control charging. Charge current starts at around 250mA and then drops rapidly to less than 100mA.

The lithium cell is protected from over discharge by voltage monitoring in the microcontroller.
During use the battery charge status LEDs indicate the following:-
The green LED is lit between 3.2V to 4.2V.
The red LED lights between 2.9V to 3.2V.
The red LED flashes between 2.6V to 2.9V.
The unit shuts down below 2.6V - roughly the same level as a DW01 protection chip.

The current passing through the LEDs was tested with the lithium cell connected and also with a fixed 4V from the power supply. The current was the same, so the cell isn't limiting current.
As the voltage falls during use the current and intensity will reduce too.

Spotlight:-
Full intensity = 188mA
Low intensity = 45mA
Strobing = 100mA

Side lights:-
White = 63mA
UV = 72mA
Red/blue flashing about 20mA.

This light cost about £2 plus UK government tax. It came from AliExpress (not a sponsor):-
https://vi.aliexpress.com/item/1005006262447877.html



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