FW3A Turns On and Becomes Stuck When Tail and Head Tightened

Huh, need to check what i messed up

Where can I get the tail switch?

Thank you!

Well, mine is mainly a shelf queen, due to the fact the button way-too-easily activates when pocket carried. But, after reading this discussion, I’m going to make it a shelf queen-on-a-metal-lid. I suppose I could take the battery out, but I prefer to keep cells in all my lights or I’d never use them.

The FW3A has a hair-trigger switch. To avoid accidents you can:
a- Lock it out. Turning the head ¼ turn does not really mechanically lock it out since there a two parallel electrical circuits. To make that happen you have to unscrew the head so far it almost comes of.
b- Electronically lock it out. But you still can drain the light accidentally because in lockout the switch provides you with a momentary moon mode.
c- Do what I have done HERE. The light is “alive” but it will take a miracle before you accidentally can press the switch.

As for the rest of it: on receiving a new light I always take it apart as far as possible. Look for coarse threads, foreign particles and debris, and lube various threads and rings before I put in a battery. And please do remember, this light was designed to accommodate an UNprotected flat top battery. Like the 30Q.

Lumintop Victor Zou

Thank you!

Hey there, thanks for the info. Mine are 3 prongs. That angle just makes it look like a 4 prong. Watch from this point: FW3A Flashlight Stays on When Tightened - YouTube


Those still don’t look correct. The prongs are way too big. Look at my picture and the spacing between the prongs, then look at yours. Or post an up close still picture

edit… looks you have a button top cell there. These FW3A’s require flat tops for spacing purposes. Button tops will add a few extra mm to the length of the cell. I’d bet that light will work just fine with a flat top 30Q

That looks a standard flat top 30Q to me. You can tell because the button does not rise above the level of the wrapper.

I cannot tell from the video clip, if that is a button top… you will likely have to stretch the springs to get it working with a true flattop. Don’t ask me how I know… :slight_smile:

Hmmmm, very interesting. My batteries are flat tops with 3 prongs. However, I do see your point about the prong width. Mine are significantly wider. I’ll start another thread in the battery forum. Thanks for the heads up.

Link to new post and photos: Fake Check Please (Samsung 30Q)

After reading this thread, it makes me nervous as hell now about this light. I’ve had a couple instances myself of this light not turning off right away. Sometimes when double clicking to turn on turbo, the light won’t shut off after clicking multiple tries. After fiddling with the switch some more it will finally shut off. This is not a good thing. If a light can’t be trusted, what good is it?

I had another hot pocket with mine yesterday.
Kind of awkward when somebody at the dog park says “your pants are glowing ….”?

Was I just extremely lucky with the two examples I had in-hand? Both were slightly flaky upon re-assembly, but following the troubleshooting steps made them super reliable. I haven’t had a single problem since the switch O-ring mod, and the only problems before that were accidental button presses.

Beem wondering the same. Other than a couple accidental presses, haven’t had any issues at all with my two.

Always had issues with the light going into stepped ramping (I hate it)

Finally looked it up. Simple 3 button press.

The guide said

“reasons to take off tail cap:

To change the clip
Because you just want to ;)”

Well…now I wanted to.

First thing I noticed was the button wasn’t as smooth or easy to press.

Second was it starts turning on by itself.


This is not a recent post. Has been a satisfactory safe solution establisbed since?


I have two FW3A flashlights. One is using the 18650 body, the other an 18350 copper body. I initially had some flaky problems with my 18350 one. Mysteriously resolved. About 3 battery changes later, I had the exact same problem initially described here. I took the whole thing apart. Cleaned it. Put the tailcap on first, then the head. Can’t get it to work right. I spent 30 full minutes screwing and unscrewing, over and over and over and over and… I’m done with this .

I love the FW3A in 18350 format, so I decided not to give up.

I think I figured it out. It seems that the machining of the driver retaining ring might not be absolutely perfect. And the battery tube contact end may not be a precisely perfect circle. Just the right orientation must be causing a short somehow. I solved my problem by loosening and then tightening the driver board retaining ring. I did not tighten it to the exact spot as before. I was a little more gentle. Suddenly the problems are gone. I have no short.

These are the standard problems for FW3A

The double-tube design is unforgiving of sloppy tolerances. It requires everything to be manufactured well and assembled correctly. And the user must not abuse it too much; bang it around or drop it.

Some FW3A are much better than others in this regard. Some owners have zero problems. Other owners have problems that require disassembly, inspection, re-assembly, tightening etc.

It is the luck of the draw and I assume it gets worse over time since Lumintop seem hell-bent on cheapening it.