>>1933466Whatever you want. It might blow it up. I have had cheap LED strip lights from HF (the free blue ones) and the way they’re built, I believe they rely on the dogshit 3x AA batteries as a current limiting device. So even while technically the 3x AA is 4.5V and the 1x 18650 is ~4.0V, the lithium cell puts way more power through those LEDs and they don’t last long. But I believe this is mostly a result of HF being cheap as fuck and trying to make the lights for the least amount of money possible.
I’m no electronics surgeon guy, I just messed around with a few lights in my garage. Read an article about how lithium cells work. They’re all ~3.7V, so if you have a device that runs off 2 or 3 1.5V alkaline cells, they will likely run off a lithium cell. But you need a protection board because lithium cells need to be charged a certain way and need a cutoff when they’re discharged, otherwise you will destroy the cell if you had it directly hooked up to a flashlight and left it on in your backpack for days.
You can buy 18650s with protection built in. Lots of flashlights use them, some cells even have a small USB charging port built into the actual cell.
What headlamp is it? Is the lithium battery inside going dead or something?
