Peak El Cap QTC problems

[IanJ]

I'm just curious to know if anyone else has run into this problem -- I'll be talking to em-mgt about it after the holiday has passed, and I hope they'll be able to provide a solution.

I have a brass El Capitan, with a gen 2 QTC pill. It worked as expected (slow ramp up to full power with increasing pressure on the battery) for about a week, but now pretty much all I can get is a sort of moonlight mode, followed immediately and without any ramping into full power. Sometimes it will vacillate between low and high power even without touching the head. I got the light because I mostly want to use it in a 10-15 lumen range, and the full power, while impressive, is huge overkill for what I actually need and want. So, it's really not ideal as it stands.

I see that I've dented the battery's + terminal, so if replacing the damaged cell would make a difference, I'd be curious to hear that (I'm not near spare cells at the moment, or I'd test it right now). This is the alkaline AA em-mgt sent along with the light.

Other than the QTC problem, I really like it. If the QTC feature worked as advertised, it would be a great EDC light. I came from an original HDS EDC Basic 42, which served me well for 8 or 10 years, but the switch has started to go. I wanted to find something AA powered to replace it, and would really like this El Cap to be the end of my search. I'd appreciate thoughts on how common a problem this is, possible solutions, etc. As I said at the top, I'll be talking to em-mgt about the problem once the holidays are over.

 

[gunga]

I both love and hate qtc. Simple enough, and when it works, it's wonderful. It's also inconsistent and can breakdown fast (even though advertised for thousands if cycles).

Just pull the qtc pill out of the bottom of the tube. They are easy to disassemble too. Just clean up the qtc (little rubber square) with your fingers to remove loose pieces that may have flaked off. Reassemble the pill and it should be good as new. If not, disassemble and repeat.

It's easy to do.

And yes, this happens a lot with peak qtc lights.

 

[IanJ]

Ok, cool. Thanks for the reply.

To pull it out (since it seems to be somewhat captive, and I don't know how fragile this thing is), what's a good way to do it? Tweezers? Shake and tap? Am I pulling on the pill itself, or the thing that looks like a plastic hexagonal halo around it? I don't want to damage anything.

EDIT: Never mind, it was clear as soon as I started trying.

For others reading this: I just had to tap out the QTC pill by tapping the battery-less tube against my hand. The whole assembly dropped to the threads, at which point I grabbed the plastic halo with a pair of pliers and pulled it out. If you haven't seen one (as I never had), a QTC pill consists of a metal bottom cap, a metal top cap (which is the hexagonal thing you can see at the bottom of the tube), the plastic halo piece, and a miniscule piece of foam rubber with a hole in the center. The top and bottom caps are loose, and the halo holds the assembly loosely together.

To re-insert the pill without it falling apart, I assembled it (from the top: plastic halo, then pill top cap, then QTC material, then bottom cap, all stacked together), and gently pushed it back into the tube with the battery tube opening pointing down. Once it was past the threads, I pushed it to the bottom with the battery.

The cleaned pill works better, but is still jumpy, no longer having the smooth ramp it had initially. FWIW, this is after I'd turned on the flashlight well under 50 times, probably more like 20 or 30. Cool technology, but nowhere near as robust as I'd hoped. At least it defaults to full power in a failure condition.

 

[arty]

I haven't tried this, but wonder what would happen if you remove the pill and tried the light by inserting a battery. Is the battery case too long, or would you just wind up with a full-power, level 8 light?

 

[IanJ]

I don't know if the threads go deep enough to take the pill out entirely, but if you took the QTC foam out from the center of the pill, it would just be a level-8 light. That's why its failure mode is full-brightness: the QTC material keeps the top and bottom caps from touching, and once it's compressed enough, they touch and transmit full power. Up until that point, the power is sent through the QTC material, thus the lower light levels.

 

[gunga]

It would be too short. Just replace the qtc material with a bit of foil to make it a 1 level (level 8) light. You can rub the qtc between your fingers to clean up loose bits. You may even want to shim the pill with a small amount of foil (I have used part of a foil pie plate before) to take up any slack. This often returns the qtc to full usability. I agree Ian, it breaks down fast at times. The gen 2 pill is better, but they should have used hex disks on both sides to eliminate an rotation. The shear breaks down qtc very fast.

 

[dudemar]

I agree Ian, it breaks down fast at times. The gen 2 pill is better, but they should have used hex disks on both sides to eliminate an rotation. The shear breaks down qtc very fast.

I agree. The other option is buying extra QTC material and replacing it when it wears out.

 

[arty]

There are some unexpected puzzles here. My light seemed to be difficult to turn on yesterday. I removed the head, and merely screwed it back on. The problem disappeared. I don't get it.
Any ideas?
Incidentally, how thick is the QTC material and how thick is the entire pill mechanism? I wondered how much this lengthened the battery case.

 

[IanJ]

I didn't measure, but I'd estimate the QTC material is about 1mm thick, maybe 1.5mm. The pill assembly is around 7-9mm thick grand total, still guessing. Next time I have it out, I'll try to remember to measure it.

How hard is it to get new QTC material? That would be pretty handy to have.

I wonder if you could add some shim material to the bottom half of the pill (inserted between the pill and the plastic ring) to keep it from rotating as easily. I may play with that too, next time I have it apart.

EDIT: I couldn't resist, and took my pill back out. The whole assembly is right around 5mm thick (measuring against a ruler, as I have no calipers handy). The QTC material is a bit less than 1mm thick. Cleaning off the QTC material helped again, but this feels like a losing battle -- it's only been a couple of days, and already it was back to the off/on binary state.

 

[RobME]

I don't get it. Peak's very helpful... just email them for a pill replacement if need be.

 

[No really]

I am having similar, but not identical problems, also with a brass El Cap, pretty new. After some pocket time, the low end is just gone. 'Start' happens at about mid-power, after some time on the dresser, low returns. This is a problem if, like I did, you leave the light just 'kinda' off, twisted back until it appears off. The low end returned and terminally drained an unprotected 14500. I know, shame on me, I'm generally more careful, but...

The light is quirky, and the pill in this one is just not as cooperative as other posters' seem to be.

I love the fact that the light is brass, I am fond of Peak products, their people and (generally) their operation. But until I work this out, methinks I'm back to a Photon Proton Pro for my single cell adjustable output needs.

UPDATE Well... I finally got the pill to appear, contrary to the description earlier, neither top nor bottom caps were loose, but fixed to the white 'halo' piece. The QTC material is not accessable. This halo has a top and bottom rim, with a C-clip like bit made of a springy black material between. The black C-clip turns freely. Remove the C-clip and reassemble the light, it works like a charm, much more sensitive in adjusting, but flawless.

Re-insert that clip, not so much... I'd guess I'm courting warranty troubles--

 

[IanJ]

No, really: if you push the hex cap into the white plastic halo, the bottom cap should pop loose. If you do that, be careful not to lose anything: the QTC material is miniscule and black, and would easily disappear in a carpet or a cluttered room. Your halo may be tighter-fitting than mine. However, you gave me a great idea about my problem with the QTC material.

This light more or less operates with a spring at the tail of the battery. That spring force is provided by the QTC foam. Being foam, it naturally compresses much like a spring does. However, being foam, it can also take a "set" when it receives steady pressure, which slowly releases when the pressure is removed (that's why the light seems to turn itself on if you don't unscrew the head enough). I keep my light in a little belt holster because I'm a huge nerd, and, like my HDS, I'd been storing it lens-up. This provides constant pressure (in the form of battery weight) on the QTC material, resulting in that set. I think this is an important factor with my problem: as long as I leave that constant battery weight on the QTC material, it's just not going to have the low-light performance I want, because it will be pre-compressed past that point.

The short-term solution to this problem is to store the light lens-down. I've done this for the last ~15 hours, and sure enough, the light has much more reliable low-light performance. A longer-term solution, and one which is favorable from a usability perspective, but negative from an engineering standpoint, would be to put a small leaf or coil spring (more likely a leaf, without a redesign of the QTC carrier assembly) in the base to support the halo against battery weight. This would be just strong enough to hold up the battery against 1G of gravity. When you screw down the head, you can exert many times the force of gravity, so the spring and QTC material compress at the same time, and you wouldn't really notice a difference in operating force. However, the QTC wouldn't be pre-compressed, and would work more like we all expect it to. This may be positive or negative as regards QTC material life, I'm not sure. The carrier assembly could be a bit better designed to resist rotation, which is probably more important than whether the foam receives constant pressure in terms of material life.

I may take some measurements, and see if I can find or fabricate a small spring to test out my theory. My holster is harder to use with lens-down carry, although it's not a huge deal. For the anti-battery-weight spring idea to really work properly, the carrier needs to be redesigned so that the spring force can be transferred via a solid mechanical connection rather than the current loose press-fit it would be using. Interesting, interesting.

 

[eyeeatingfish]

so has peak fixed the problem with their QTC pills?

 

[gunga]

Depends on what you mean by "fixed". I'd say, no.

 

[arewethereyetdad]

gunga, you are quite right about the issues surrounding QTC in general, and Peak's version specifically. Conceptually, QTC should work like a charm every time. But I've found that it IS somewhat inconsistent in performance. If memory serves me, for a keychain Peak QTC it is possible to convert it to a single level momentary switch so long as the tail contact stem is long enough. There are two different sizes for this stem, so you need to make sure you have the longer version to account for the missing QTC pill. I'll defer to gunga, however, as he seems to have an excellent handle on this issue. :thumbsup: