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

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.

Any reason not to get a protected battery like the panasonic ncr18650b?

You are bound to measure the same voltage across both LEDs (due to single resistor supplying both.)

But any small difference in Vfs between the LEDs would mean the lower one would hog the current, hence one bright, one dim.

Agreed, 1 resistor > 2 LEDs isn’t the best way.

Guess my OCD is worse than yours… I actually fixed mine. You can see that the SW leds are lit so it is contacting. I have swapped my SW LEDs to dimmer white.

The high power consumption of this light may shut off the protection circuit if you try to use the highest levels.

Sony VTC6, Samsung 30Q, button tops. The Sony VTC5A is also a top performer but difficult to find with button tops applied. I got 8 of the 30Q with button tops for $5 each at LiionWholesale.com, they had 400+ then, but I don’t know if they still have them.

Okay, so I have done some measurements on my switch board LED and resistor. The resistor is measuring at 15,130 OHMS and I am passing 1.453VDC on to the two LED’s. The switchboard LED’s stopped flickering after some more use of the lights. The voltage on my batteries is around 3.8V. Applying a full regulated 4.1VDC makes the LED’s light up like they are supposed to with 2.4VDC going to LED’s. Now here is the odd thing… After putting my partially drained batteries back into the light, they two switchboard LED’s lit up again for a short time, although one a little brighter than the other. I have measured the resistance across the LED’s themselves and found one to be at 61k OHMS and the other to be at 68.5k OHMS. Not sure what to do with this information, but I will probably be replacing the LED’s in mine as well as the resistor to hopefully higher quality components. Disappointing, but I guess that is to be expected from a first run. Is there any possibility of Thorfire offering replacement switchboards for those who wish to repair their lights?

Is there any way to modify flat tops? LiionWholesale doesn’t have any more button tops :frowning:

Aside from that battery not being any more “protected” that the 30Q?

Not really, but before buying one’s first “protected li-ion battery”, one should be aware of who manufactures what. “Protected” Panasonic NCR Bs are comparable to, say, Trustfire, Keeppower or Nitecore branded batteries. Not comparable to normal Panasonic, LG, Samsung etc. bare cells.

Company A (typically someone big) made a li-ion cell. Company B (when buying “protected panasonics” an unknown sweatshop) rewrapped them, sometimes in clear plastic and fit a protection PCB and nipple. Company C made the PCB. From saying “a protected battery like the panasonic ncr18650b” one will have a long way to making an educated guess who made what.

TL;DR: It’s not Panasonic who markets those.

You can’t really learn much by trying to measure the resistance of an LED probably nothing, because a typical multimeter won’t apply anywhere near the Vf when measuring. Particularly when still connected to the de-powered MCU on the driver (whose internal protection circuits might be expected to provide another current path),

If your meter has a “diode test” setting that could provide useful information, but most such meters are set to measure switching diodes, typically less than 1V Vf. I do have one meter (a very cheap one) that can measure Vf on it’s diode test setting, up to about 3 V

The diode test setting usually applies a constant current of 1mA through the diode, and measures the resulting Vf. It’s actually very handy to check parts before or after assembly, because 1mA is enough to light up even big LEDs sufficiently to show that they are working, or with these little SMD leds light them up very brightly.

Oh ok. Well thank you… Is there any problem buying the 30qs from banggood then? Since no US retailer has them in stock?

got my 1st light today. had the charged up LG cells ready while the samsungs were charging so i tossed them in.

man is it bright. cant wait for night. :slight_smile:

my switch LED’s are working fine so far.

thanks to those who made this light possible.

Brian