Question: I've had [a cheap 18650 flashlight](https://de.aliexpress.com/item/4000396427849.html) for some time now - when turning it off and on, it cycles through five modes - full power, medium power, low power, strobe, SOS signal.

I'd like to disable that feature and just use it in full power mode whenever I turn it on.

[![enter image description here](https://i.stack.imgur.com/KnxtV.jpg)](https://i.stack.imgur.com/KnxtV.jpg)
[![enter image description here](https://i.stack.imgur.com/c4xUu.jpg)](https://i.stack.imgur.com/c4xUu.jpg)

I assume the "HL6S2" component controls those modes, but I couldn't find any useful information on that.

Positive power comes through the via near the red lead.
Ground is on the perimeter of the chip.
The flashlight is turned on and off via a switch on its back, which connects the case to the battery ground, so the IC seems to have some sort of memory to retain its information for prolonged periods of time.

I assume the IC switches the left leg (connected to the blue lead via two 500 Ohms resistors in parallel) to ground, which is on its middle leg.
Does anyone have a datasheet for this chip? Searching for the markings wasn't very helpful.

To mod it, I'd remove the IC and solder a bridge from the left to the middle port - does that sound reasonable?

Answer: 
Here’s the problem. You need to actually see the data sheet of that ASIC to see **what else** it does.

I polo mean, obviously, what annoys you is the multiple modes, and that’s what you want to change. But that target focus is making you and several others here to create a false narrative, *that the annoying mode select is the only thing that chip does*.

That is highly improbable.

After qaffgw. all, we’re dealing with a lights made in tens of millions quantity. T here are several other tasks that need to be done in a flashlight like this,and here are two:

* battery protection for the LiPo
* current limiting for the LED so it can be driven at peak performance.

That little 3-pin chip is in a good location to do both those things. Given that these chips are made in million quantity, it would be completely insane to *not* include those functions in that chip (thus forcing flashlight builders to use 2 chips).

You need to find this stuff out.

And the problem with niche ASICS like this is, there *may not exist* well-detailed documentation on these chips. Why would there need to be, everyone in Shenzhen who makes cheap flashlights *knows each other*... and all they need to know is”follow the schematic”.

To the extent they do document, it’ll be in Chinese, and they’re not going to do an English translation for something this niche.

I get where there’s ”fun trying”, but that is a very time-expensive way to learn electronics. You’re not learning much, and it’s bad lessons.
Since you are on this site, curious and inquisitive, I assume you'd much rather modify the design, rather than work 2 hours in a menial job to buy a different flashlight.

So what you could do is use the push button to switch it on (100% was the first mode in the cycle?), and for switching OFF you could solder a second "normally closed" push button to cut off power from the battery. This would work if the flashlight powers up in OFF.

Should it power up in ON, then you'd have to use a normal toggle button in replacement of the current one.

But if it doesn't start with 100%, then you'd have to replace the whole control unit with a resistor to set the current, or use a regulated current source.

The resultant joy and satisfaction from making your own mod can never be supplanted by any amount of cleaning or burger flipping.

I also think this is the reason whay many of us are here, so you are in good company.