[Solved] Flickering occur at high temperature.

Hi everyone. I’m working on a XinTD C8 mod and I am using XM-L2 T6 80+CRI LED reflowed on Noctigon, Qlite 12*7135 driver. I use INR 20R and measured 4.50A at the tail.

After switching it on for more than 20 seconds the head gets uncomfortably hot and the light starts to flicker. I suspected if there is any poor contact at first, but when the light is cool and switched on again there was no flicker, and it comes again when the light is getting very hot. There was no change in tint at all, and the hotter it gets the more flickering it gives.

The modes work great. Is there any chance of the LED damaged? Has anyone encountered this issue?

Is the reflector shorting on the power into the led on the star?

Definitely not. I have tried this without putting the reflector on and when the head gets very warm the LED starts to flicker. When the light was cold everything was normal. I suspect that the LED was damaged but no visible tint shift at all.

So it only has this problem on high?

it can on / off button are also those too poor to transmit power.
I had one once that melted.
the springmod corrected the problem with me.

Is the Noctigon thermally bonded in any way to the pill?


Maybe a tiny film of artic silver under the Noctigon if it is just laying in the pill compartment might help get some of that heat out…4.5A is ALOT on an XM-L…3A is 300% rating, so you are pushing it beyond that, at that range extreme heat is going to happen

Pushing a Cree without proper heatsinking can and usually does result in damage, I can’t imagine how much heat that thing is pumping out

The flickering issue had been addressed before in this post, together with the loss of moon.

I had a flickering light as well (P60 with bad heatsinking), in my case it was the Qlite RevA driver. After 3A for a while, moon was gone temporarily. Cooled down, moon and low started to flicker. I changed the LED and the problem stayed, I changed the driver and the flicker was gone. I hooked the driver to another LED and it flickered. I binned the driver and followed comfychair’s path of heatsinking the P60 with a copper ring.

good luck

MRsDNF, When the light is hot, flickers occur in ALL modes.

penumbra, if it is the switch then I think the flicker would persist even when the light was cold?

WarHawk, yes, I have applied AS5 under the noctigon. I have modded other lights some even driven with over 5A are doing well.

HarleyQuin, well I didn’t choose the moonlight mode, just lo med hi. Whether the driver or LED is damaged at this point I believe, have modded few high current lights but this is the first time I encounter this. :frowning:

Appreciate all of your inputs.

Like the others have said I would definitely want to rule out the switch and all other electrical connections, flickering in every mode always tells me to check ground first, then look for other issues.

Ran my Xintd c8 on high for 10 minutes started flickering then died, discovered a dodgy switch, in fact looked like it couldn’t take the 3amps

Mine isn’t heat related but it seems to be a Qlite driver problem. I prefer the dimmer low mode (in 2-mode) of the old Nanjg 105c anyway. None of those flicker in my other lights.

Your problem sounds similar with mine, but I am not sure, I thought some people like RMM and Tom E have done many XinTD C8 mods with high current draw and don’t seem to have switch issue?

The switch was junk quality, got another from Hank at Inoutdoor, haven’t run it on high again, hopefully a one off

Is your XinTD a V3 or V4 and is it a reverse or forward clicky? I've only dealt with the V4 with a forward clicky but they've all been good so far with the 5A+ I've been pushing through them. Maybe the older reverse clicky wasn't as good? Even the OMTEN switches are only "rated" for 1.5A, but we put 7A+ through them all the time. Of course it's going to wear out faster but it does seem to work.

Have you tried bypassing the switch yet?

Was a V4 forward clicky, very new , was just curious how long it would run on high heat wise, as mentioned 10 minutes then poof

I've run them until the head was too hot to hold, not sure how many minutes that was. Probably 5+ minutes.

I’m curious what comes of this. I seem to be having the same issue with one of the lights I’ve been modding…

I go back to this light now and it is definitely not because of the switch. I use a tweezer to cross the tail and the light start to flicker when it is very hot.

One quick question people, does this Qlite has some sort of thermal protection/step down or similar thing? I guess not?

It doesn't have any sort of thermal protection or stepdown, but the problem may still be the driver. Easy way to rule that out is to run the LED in direct drive.

The 7135 are rated to work up to 85C, from my personal experience they seems to have problems as they hit around 70C. As for thermal protection there is a function on the 7135 at Typical 140C