Q8, PMS SEND TO THOSE WITH ISSUES BLF soda can light

Mailman just dropped off my Q8. Very first impression, its much smaller that I thought. I am just getting into this hobby and don’t have experience with the soda can form factor, I just assumed in my head it would be much thicker and chunkier feeling. This light is pretty much perfect in my hands.

I really really really like this light!

In the interest of accumulating data… no flicker issue with the switch indicator LEDs as of yet, but as another user noted, the left side LED is noticeably brighter than the right side LED in the switch.

Again, many thanks to all the guys and girls who did the heavy lifting around here to make this possible. I’ll be putting in my second order shortly.

You are a neighbor, so free modding for dropoffs! Let me know if you want anything tested, tweaked, etc.

Ah, I appreciate that! I’m sure I’ll find something at some point I want to change.

Do you know of any documents I could take a look at to really start to understand the nitty gritty as it pertains to this hobby? I’m a network engineer and developer with some soldering skills and experience with arduino and the like… however, I’m having some trouble really finding a place to start from the beginning when it comes to all about these type of light’s internals.

Everyone just kind of expects that you are already an expert on FETs and have an EE degree.

Are the switch indicator LED’s supposed to be like that? One much brighter than the other? Could this be an early sign that it might fail in the future?

This could signify lights that had LEDs from two separate manufacturer batches with a different Vf if the resistor value is the issue as amplificus noted. Indeed it could be a way to determine what lights have a combination of two different batch LEDs.

I’ve received mine today, got the 30Q’s earlier in the week.
It works very well, powerful and a nice combination of flood and throw. Narsil UI is a recipe for instant love for sure.
I have the kinda-sorta but not quite issue of one of the switch LEDs being brighter than the other, enough so that I’m not sure if it’s just one of them on or just a massive difference in brightness. I’ve tried to get an image of it to illustrate, but the lit up button on the background of black aluminium is confusing the autofocus on my cellphone, so those pics just looks like a single blob of light. if I were to try and explain how it looks, the one on the right is bright, and throwing a shadow of the outline of the part of the silicone nub that reaches down to the switch, and there’s a hint of a green glow in this shadow, presumably from the other LED.
I’ll be leaving it with the button led(s) lit to see how it develops, and gonna try to borrow a dslr so that I can get a clear picture of it.

I got my first of two in the mail today. I’ve had it for about 4 hours now…been playing with it here and there and I’m pleased to report that there are currently no issues with it.

Mine is still working fine thankfully.

But there is one thing my OCD cant cope with and that is that fully screwed in, so it can be switched on, the lines are not lined up to the top half ;-(
How can that be fixed?

I mean like it shoul;d be either like:

Not like:

on my bangood account this just showed up
my god what a long wait still…………

Order Placed Date: 2017-09-09 09:06:42
Expected Shipping Date: 2017-10-09 09:06:42

thats pushing 3 weeks still, just to ship……ughhh…….

Yeah!!! received mine. Happy to report no issues, other than self inflicted :stuck_out_tongue: Got a little click happy, and had to break out the manual. Switch led’s appear fine. No issues with them getting, flaky. Looking forward to dusk, to check it out.
Thanks to the Q8 team, and Thorfire for putting this together.

It is an excellent quality light, that was worth the wait :+1:

I’ve had this kind of misalignment on many lights (and other devices with parts that screw together))… and lived with it most of the time. Though i haven’t tried i believe that a round washer on the driver side could fix it. The trick is to have the exact right thickness so the tube stops screwing in the right position.

Note the 20A from turbo will go through it, so a nice and polished piece of copper would certainly be welcome. Tin foil comes to mind but may add a weak point in the current loop - or not idk.

First: Kudos to the team, and Thorfire, for stopping to take stock and get this right.

A correct but difficult decision. I am all the more impressed with the leadership demonstrated here. This has encouraged me to order my second torch.

When this is resolved, which I am confident it will be, it will further strengthen my respect for Thorfire. They are giving it their attention.

Second: here is my take on what might be happening. Just a theory.

The technology for making natively coloured LEDs differs depending on the colour. Technically, the wavelength emitted is a function of the bandgap of the compound semiconductors used. Practically this means that the forward voltage needed to light up the LED is different for each colour.

As it happens, green LEDs require one of the highest forward voltages. Typically above 3V. I.e. much the same as a single lithium cell. Leaving almost no headroom for further voltage drop across the series resistor used to set the operating point (current level).

If I was asked to specify e.g. a typical green 3.3V LED, to consistently light up from a typical single cell (say voltage ranging from 3V to 4.2 V, I could not do it with just a series resistor.

I would argue for using a different colour, e.g. red, orange, yellow etc, with a Vf around 1.8V, leaving plenty of headroom for the series resistor to control the current across the full range of battery voltage.

I would only consider using a typical green LED if it could be driven from more voltage, e.g. in a 2S light, and even then, preferably from an MCU pin set up as an “open collector” or “low side drive” output capable of handling the full voltage.

The MCU in a 2S torch, would be expected to be supplied from no more than 5V, possibly as little as 3.3V, so a direct drive from an MCU pin might be marginal at best.

In the Q8 the MCU is driven from battery voltage (minus the drop cross the reverse protection diode) so tracks the battery voltage as it varies with charge level.

I read that the switch PCB was derived from that of the Thorfire S70 a 2S torch. Is it possible that the same green LED is being used in the Q8, with perhaps resistor value change to try to compensate for the 1S Q8 ? If so, maybe it is right on the edge of working, and e.g. small shifts of Vf as the LED warms up, or during initial ageing, or between the two LEDs, are enough to tip things over the edge.

If this turns out to be the case, I suggest that the green LED be changed for one with a much lower Vf (and different colour), and the series resistor value adjusted to suit.

Anyway, I’d just like to throw this speculation into the discussion. If I had my Q8 already I could do a few simple measurements to see if this has legs. I.e. anyone with a torch with functioning LEDs, and a multimeter, please measure the voltage directly across the LED whilst it is illuminated (I.e. Vf). and report back.

Good tip :wink: Or if its really close mill or sand off a bit of the bottom half?

only my opinion, but I believe that stop shipping just because 4 flashlights on 500 are “defective”, it’s exaggerated

Perhaps by “indexing” the battery tube, meaning carefully sanding down the end, bit by bit, until it lines up nicely. But only try this if there is enough thread left for the tube to be screwed on further. A quick check would be to take out the driver and see how many turns are available before it bottoms out on something. If this is say one more turn than needed to fit it with the driver in place, then it should work.

The above is very valid in theory but my experience with lighted tailcaps, that use the same type of leds and single li-ion cell, is that green leds light up fine during most of the drainage of the cell, while red leds of course light up always, and blue leds do dim significantly when the cell is half-drained.
So these green leds should do fine, and indeed they do in my Q8 prototype and so it seems in many production lights.
Or it has to be that Thorfire used a green led with particularly high Vf (-variation), but I always thought that the Vf of 532nm leds is determined by the technology and does not really vary that much.

I can have the proto work with the flat aligned, but it is less bright. It is such a short twist in unscrew direction it seems hard to fill it.

No don’t think so, er don’t know the extend and so far it is 4 in the delivered and no way all 500 are in. At best it is 1% and well we don’t want 20 with the issue, each one is one too much.

I measured 2.10V with fresh 4.2V batteries.

yep, been done already. Measured 2.247V across each LED on one light that has 2 different brightness's, on the prototype measured 2.167V. Think the higher voltage is why the production Q8's switch LED's are brighter than the prototypes. Ideally design wise, would have been better using 1 resistor per LED. We've relayed all the details to ThorFire.

If the LED is being driven from a straight MCU output, rather than a low side drive, then it is not the same as a simple lighted tailcap, there would be additional voltage drop across the reverse protection diode, and any other series resistance in e.g. a transient snubbing circuit, as well as within the MCU output driver itself to consider.

I’m used to doing worst-case analysis using max and min datasheet parameters, which is why I said I l probably could not sign off such a design, but in the real world thing usually work better than that. Suck it and see is also a valid approach, but can sometimes lead to surprises once production starts, that were not evident in small quantities of prototypes etc.

There is a difference between e.g. a modder hand-tuning a few lighted tailcaps to their personal taste, and the small batch of LEDs that they have on hand, compared with committing to production run of 2000, where the knock-on consequences of having to repair or replace even a tiny percentage of failed torches after they have been delivered, are significant.

Anyway, if a few people could measure their LED Vfs we might soon get an idea of the mean value and actual variations, whether the batch of LEDs has significant variability, and whether the design is solid, or a bit marginal.