FW3A won't turn on. SOLVED

Just got a new FW3A as a gift from my son. Charged the new battery, installed it properly, got the blip of light when replacing the head, but the light will not turn on. No response from any clicks. What did I do wrong?

I'm not sure what's wrong, but check out the OP of this thread:


Read this thread, it should explain any issues you could have. I’d first check and see if the retaining ring in the tail is tight, if it is tighten the tail cap down as good as you can then try to tighten it more. Then install the battery and then the head. Tolerances on the FWXX lights are really tight so it needs to be cranked down a good bit for it to work properly.

the head needs NO big force !! (the tail does)

i saw people damaging the inner tubes because of a simple "tighten everything a lot!"

I wrote to the selling retailer and to Lumintop and am very hesitant to attempt any fixes on the brand new FW3A, lest that mess with the warranty. Not too happy about some of the posts I read about getting any joy from warranty claims!

I’ll wait to hear from those to whom I emailed and I’ll post what happens here.

Thank you all who replied here!

please let us know which cell you are using ?

if its too long the switch does not get contact - no "fix" will work then!

The cell is an 18650 Sanyo NCR 18650GA 3500 mAh High Discharge BUTTON Top. It was shipped with the FW3A by Illumination Supply LLC in San Jose, CA. They specialize in these things, so I do hope they shipped the correct cell!

BTW, I got a reply from Lumintop Tech Support:

Lumintop <leo@lumintop.com>
6:55 PM (2 hours ago)
to me

You please tightly a little the tailcap and then put the battery into the tube.

Meanwhile please use the flat unprotected battery(66mm length)


That’s the problem, you can not use button top battery. Use flat top battery like Samsung 30Q, Sony VTC5/6.

^ this

Well, OK! Thank you! I’ll let the seller know and see what they have to say. I hope it’s really that simple!

I’ll follow up.

I hope illumn didn’t recommend you to get the button top…definitely needs a flat top battery.

I had the same problem.
I found that it was not being transferred - to the lamp body. The problem was in the PCB in the tailcap of the lamp.
Try to measure if it is converting - from the spring to the part of the PCB that touches the lamp body.
Using soldering I solved the problem.

The very first thing you have read in the FW3A Manual was (literally copy):

Safety precautions

  • Use only a reputable 18650 cells of known origin. Quality high drain cells (over 10A) unprotected, flat top type cells, from Samsung, Panasonic/Sanyo, Sony or LG are recommended. The supported maximum length is 65mm.

That was NOT a suggestion.

If the problem persists even after using a correct type of battery try this:
Take head,barrel, tail and inner sleeve apart.

Re insert sleeve into barrel (make sure the thin translucent band is in the correct place just below the shoulder on the sleeve), put on the tail cap only partially tight.

Using your finger inserted inside the sleeve, turn the sleeve and incrementally tighten the tail cap until you can feel the resistance of the sleeve pushing on the tailcap’s PCB as you turn it.

Feeling that there is good direct contact, give it one more turn for luck(!), then tighten the tailcap as hard as you can. When the tailcap is fully tightened, you should not be able to turn the inner sleeve.

Reassemble light with battery, switch on.

This is the technique that I found to work when the connection between sleeve and tailcap PCB was bad. It’s also a good idea to ensure there is no grease etc on two thin end surfaces of the inner sleeve.

yeah just buy a samsung 30q flat tops and im sure light will work just fine.

When you have it disassembled, wipe or “canned air” blow out the threads and contact surfaces, to remove any grit or metal grinding debris.

I usually wipe a little conductive lubricant on threads and contact surfaces when I clean mine, but mentioning that here can set off a religious argument so I will leave that to Google.

Why can’t lights be designed so that they work with button tops and flat tops? Supporting either one is to induce complexity.

Same reason one type of mobile is designed to plough a field, other to drive on race track.

My FW3A Manual, on Page 3, says, “Battery: One flat top or button top 186550 cell. An unprotected cell is recommended. Max length 65mm. Cell is not included.”

Maybe that’s why Illumination Supply thought it OK to send button tops? I have not yet heard back from them. I’ll report when I do, and if I don’t hear from them by later today, I’ll call them.

My “Manual,” BTW, is just one sheet of paper with microscopic type separated into tiny blocks with a “page number” on each block. Disappointing, considering the price of this flashight.

strange, the light should come with a manual and some spare O-rings.

But it was decided very early on that this light will only work on unprotected flat tops.