Interesting:
I can hear sounds from the tailcap, when I switch in strobe modes.
At least it seems to come from the tail.
I had to press my ear on the bottom.
I have a fully stock lamp. And a 1mm thick wire between tube and driver board (as scratch guard). So my springs are less compressed
Without the wire in the head it is much less noisier.
What is this?
Springs moving via current and ringing?
Has anyone a better explanation?
Edit: That sound is also on my second lamp.
Pulsing turbo current is smth like short-cut for this springs and specialy for the contact place between spring and cell bottom. If tail was trasparent, you could probably see small flashes from bad contact areas.
This is what it sounds like, when springs cry! :cry:
This contact has been an issue on a lot of lights. Look hard at the end of the spring that contacts the cell.
Often they have been cut off a longer coil with wire nippers and left unfinished.
Is the contact with the battery made by a sharp point that will barely touch — or when tailcaps are tightened will dig a groove into the battery end plate? (That latter not an issue with Q8)
If so a little filing and bending to remove the sharp point and make the contact happen around an arc of wire, over more surface are, plus a dab of conductive lube, can eliminate the bounce problem.
This could be added to the growing list of little things that can be done to clean up and properly finish a budget flashlight, either by the manufacturer or the buyer.
Q8 2x2 LED board
Ok girls, let’s get real…
My first Q8 arrived this afternoon. I have messed with it all afternoon, just got done with the latest mods.
Out of the box it made 5409.6 lumens, now it’s making 10,039.5. Been a good day!
Edit: Ok, so I know y’all will want to know…
5409.6 on VTC5A’s with copper buttons soldered on, 5213.64 lumens at 30 seconds.
So then I pulled the mounting screws and replaced them with brass ones, this gained me 328 lumens for a few cents worth of brass screws.
I then swapped in a UCLp lens from my M6, this was only a 41 lumen gain so I put it back in the M6 and kept the stock glass one. 
Then I made a copper plate and put the stock dual springs on it, (hadn’t seen what Kawi did, funny that!) and it gave me a 93 lumen gain. Not really worth all the effort.
So then I bypassed the dual springs with a 22ga wire inside the springs, this was rather tedious but it gained me 1214.4 lumens, so it’s all pulling together at 7003.5 lumens.
Then I got real, went and put my favorite new FET on the driver, swapped in 18ga leads, and pulled the XP-L V6 3D’s in favor of XP-L2 V6 1C from Kaidomain, net gain from this last blast was 3036 lumens! 10,039.5 and I didn’t even recharge the cells this time! Wicked! I probably don’t even wanna know what the amperage is…
Woah! Nearly double? Wow!
4-50’s and 8 Aspires?
Posted in post 1025, I used XP-L2’s, new FET and heavier wires.
My Sony’s are begging me to put the Samsung’s in. 
Nice! Someone is gonna have to get firmware to support it now, but the Q8 driver does have a spare pin #7.
Dale - that's awesome! I think this Q8 has a very good low resistance circuit, once you tweak it up. The Stock springs are terrible - IOS "A" or the nickel plated stiff springs do way better.
Didn't try that yet with XP-L2's - what FET? Just got in more Infineon's and the SIRA00DP today from Arrow.
The A00DP doesn’t pan out, but the A20DP does.
I have 4 W2 5000k and 4 W2 6500k but have not the time, yet, to change them out?
Hmmm A20DP…nice!
Ohh dang! Must have missed it - spent some time researching them. Let me check the specs - yes, very good in deed!
Wow 81A steady and 500A pulsed? Wow!
Ok, will toss today's shipment... These A20's are cheaper than the SIR800DP's, wow again!
How much have these been tested? I'd order a bunch but wondering if tested in 2S+, etc. Might swap into my MT03 XHP70.2 and 16X XHP50 light, plus other single XHP70.2 lights, etc.
The A20 seems good, but should be tested to see if there are no complications
its the 4. generation of Vishay MOSFETs so one newer than the 404
compared to the 404 it has about double the capacity, so the reaction time is a bit slower,
maybe this is not good in play with 2S and AMC7135s
The 404 has still the advantage in resistance below 3.2V cell voltage, as its minimum gate voltage is over 1V less than for the A20
The A20 allows my L6 XHP-70.2 to do 9200 lumens. I’ve been using them for months now, but of course I was also out for several months. Arthritis and a bone spur in my right arm have been bugging me the past week, ice pick in the elbow, and after the left was so much trouble for 6 months, it just ain’t right!
I have the A20DP in my D4, D1, my own build Ti/Cu 18500 Quad, the L6 70.2, a Jaxman M2 with 2 14500’s to an 50.2 making 3000+ lumens. It allows my SupFire M6 with 3 SST-40’s to do 8866 lumens, manxbuggy1’s highly modified M6 with 70.2’s to do 13,558 lumens, I’ve tested it pretty well.
too bad I had ordered yesterday from Mouser 100 SIR404, could have added 10 A20DP for tests
Only at turn on, right?
There’s no way a simple flashlight host can keep the 150W LED near 25C.
Thanks for the answers.
I can hear it on all my lamps with strobe. Astrolux S42, Skilhunt H15, Skilhunt H03.
Could that be a way to tell how good the spring contact is?
Did you happen to measure 70.2 output with the stock fet?
Thanks