Modding a McClicky to handle more current?

[Noctis]

Recently I've melted 3 McClicky switches trying to direct drive an SST-90 with an IMR 18650.

Yes, the heatsinking sucks, but I believe it's manageable in the sense that the light gets too hot to hold before the tint turns blue.

Anyways, the spring in my switch always warps and the plastic melts if I use it too often or too long(longer than 5 seconds). I believe I'm running 6.5 amps through it with a fresh battery.

I was wondering if using some Arctic Alumina Thermal Adhesive to create a thermal path from the spring to the metal ring that makes contact with the brass retaining ring would help any. I believe I'm only barely pushing hard enough to damage the switch and I was hoping that drawing heat from the spring and other exposed metal components would help to prevent the obvious damage from heat.

Oh, and the most tools I have at my disposal would be whatever is in your neighbor's toolbox and a soldering iron, so low tech would be best for me.

 

[kengps]

the solution I've seen mentioned is to attached a piece of braided wire from the base to the end of the spring to provide another path for current flow. Ala spring-loaded electric motor brush

 

[EvilPaul2112]

I use McClickies in all my ROPs and Mag85s....I have found that they handle current better if I solder the metal contact to the spring. I clean and tin my soldering iron ....use a narrow tip...get it very hot....add a small amount of flux to the contact/spring....then quickly touch the tip to the metal contact and spring....solder will flow in about 2-3 seconds. After I perform this modification, I notice the spring does not get as hot as it did prior to the mod. Not sure how much more the switch can handle, but I have never had a problem running my ROPs or Mag85s for extended periods.

 

[Noctis]

I use McClickies in all my ROPs and Mag85s....I have found that they handle current better if I solder the metal contact to the spring. I clean and tin my soldering iron ....use a narrow tip...get it very hot....add a small amount of flux to the contact/spring....then quickly touch the tip to the metal contact and spring....solder will flow in about 2-3 seconds. After I perform this modification, I notice the spring does not get as hot as it did prior to the mod. Not sure how much more the switch can handle, but I have never had a problem running my ROPs or Mag85s for extended periods.

Hmm, what's the highest current you've run through the switch?

Soldering the spring to the metal contact sounds like a plan. Might work great in conjunction with the thermal epoxy and AS5.

I'll have to wait for the parts to arrive next week before I try running it on the IMR 18650 again. But at least I'll have 5 more McClickies to melt dow- I mean, just in case something unfortunate happens:devil:.

the solution I've seen mentioned is to attached a piece of braided wire from the base to the end of the spring to provide another path for current flow. Ala spring-loaded electric motor brush

I did that once, and it blew my switch inside of 5 seconds.

Rather than increasing the current flowing through the switch or lowering the resistance, I simply want the switch to survive the current without melting down due to heat.

 

[maxspeeds]

Instead of modding a McClicky switch, how about using a 14V 10A Judco switch?

 

[Noctis]

Instead of modding a McClicky switch, how about using a 14V 10A Judco switch?

The one from DigiKey?
I've looked at it, and I wouldn't know the first place to start in trying to modify that thing to include a spring(which must also be able to handle the current without warping), and also for it to fit in my tailcap.

I really lack the tools and knowledge to do something like that.

Do I talk to McGizmo about that?

 

[EvilPaul2112]

My ROPs run at almost 5 amps @ 8.5V and my M@G85s run at just under 4 amps @ 12.6 Volts. I have run both types of lights for extended periods (15+ continuous minutes) without damage.

 

[LukeA]

Rather than increasing the current flowing through the switch or lowering the resistance, I simply want the switch to survive the current without melting down due to heat.

To reduce heat damage, you either need to increase the maximum allowable temperature in the switch or reduce the rate at which the switch must dissipate heat. Because dQout/dt=dWin/dt in this case, unless you want to start making your own switches out of ceramic, you should reduce the electric work into the switch by lowering the switch's resistance to current flow.

If you reduced the resistance of the spring and the switch still melted, I suspect you just moved the point of failure from the spring into the steel internal components of the switch. I think you should either add a power resistor to reduce the current through the circuit or construct an electronic switch that uses a FET to perform the high-current switching. A tutorial featuring such a switch's construction is here.

 

[Justin Case]

My ROPs run at almost 5 amps @ 8.5V and my M@G85s run at just under 4 amps @ 12.6 Volts. I have run both types of lights for extended periods (15+ continuous minutes) without damage.

Your application is essentially within the switch's specs. Not so for an SST-90, which is rated up to a max of 9A drive current.

 

[Justin Case]

As LukeA suggests, you probably transferred the failure point elsewhere to some internal component. See this post showing a McClicky disassembled.

What are your flashlight host body and tailcap that you are using?

 

[Noctis]

To reduce heat damage, you either need to increase the maximum allowable temperature in the switch or reduce the rate at which the switch must dissipate heat. Because dQout/dt=dWin/dt in this case, unless you want to start making your own switches out of ceramic, you should reduce the electric work into the switch by lowering the switch's resistance to current flow.

If you reduced the resistance of the spring and the switch still melted, I suspect you just moved the point of failure from the spring into the steel internal components of the switch. I think you should either add a power resistor to reduce the current through the circuit or construct an electronic switch that uses a FET to perform the high-current switching. A tutorial featuring such a switch's construction is here.

I've actually considered the possibility, but it simply didn't seem doable.

The first stumbling block is that I don't have a shop with various tools inside. I'm not sure where to buy the parts, and I don't believe that mosfet would fit inside my tailcap.

I'm hoping to pursue the third option, which would be to increase the rate at which heat is dissipated. Looking at my most recently melted switch, it is simply the plastic around the bottom of the spring that's melted. So I figure the heat of the spring is the main culprit. I was considering covering that area with the thermal epoxy and "tracing" it down towards the metal ring that makes contact with the brass retaining ring. The thermal epoxy itself should act a little bit like additional thermal mass and draw the immediate heat away at least right?

My only other option is to try and frankenstein a Judco switch with the McClicky so that it fits perfectly in my tailcap.

As LukeA suggests, you probably transferred the failure point elsewhere to some internal component. See this post showing a McClicky disassembled.

What are your flashlight host body and tailcap that you are using?

With my first switch, I suspect that was the case. I assume that the current went straight up to the full 16A draw the IMR 18650 was capable of. I never kept the switch, so I don't know precisely what was damaged.

Looking at the internals of the switch though, I can't say that heat management is great.

I'm using a bored Surefire 6P host I bought from ElectronGuru. It's a Z41 tailcap with a Brass + McClicky switch.

The choice of host is poor, but I was looking to get 1,000+ OTF lumens in a pocket size host. I've tweaked the current low enough so that the light gets too hot to hold before the tint shifts to blue. There's only a mere 2 strands of copper wire soldered to the spring of the drop-in module.

I'm currently running it on an AW 18650 2600mAh cell, which gives me a lower current draw of 3.5A which the switch can handle with no problem, but now my IMR cell is sitting unused.

Long-term, I was hoping to run it in an FM 1x26650 host with Nite's finned P60 head for better heatsinking and runtimes. But since that host also uses a McClicky, I figure I may as well try to fix the problem now.

Anyone know if the thermal epoxy would help at all?

 

[ElectronGuru]

Power runs down the spring, through the switch and out to the brass ring. Wire the spring to the brass and you'll basically have a McGizmo spring holder. The only way then to shut it off would be unscrewing the tailcap. Theoretcally though, you'd have some insane amperage handling.

Just keep something in mind while considering all this. The reason you need so many amps to reach your lumen goal is because the SST's are not that efficient to begin with.

 

[Noctis]

Power runs down the spring, through the switch and out to the brass ring. Wire the spring to the brass and you'll basically have a McGizmo spring holder. The only way then to shut it off would be unscrewing the tailcap. Theoretcally though, you'd have some insane amperage handling.

Just keep something in mind while considering all this. The reason you need so many amps to reach your lumen goal is because the SST's are not that efficient to begin with.

Yes, but I wanted to avoid having a twisty setup, as buying a twisty tailcap switch would be easier.

Using a twisty with that Delrin Tailstanding shroud attached feels a bit unwieldy.

I have no intention of running 9 amps. The emitter blues within seconds of turn on at those levels. Perhaps 7 amps at peak on a fully charged IMR cell, which quickly sags down to 4.5A in about a minute or two, but still plenty more than with the Li-Co cell. I could probably reduce the resistance enough to draw 4A from the Li-Co cell, but until I get my hands on some near-zero resistance test leads to find out precisely how much current is running through the light, I don't want to risk damaging the battery by drawing more than 5.2A.

With the IMR cell I seem to be stuck between white and black areas without a shade of gray. With one strand of copper wire I get 3.6A, with two I get 6.5A. It's difficult to tweak the resistance any further to hit that sweet spot. Either that, or my multimeter is giving me false readings.


This is more or less "just for fun" until I get my Triple XP-G from milky, or until VanIsleDSM finishes his Quad XP-G and FETtie(which CAN handle the current, but I've heard nothing from him about that). Thus why I'm searching for a more immediate "patch up". Though I might still use this setup in the FM 1x26650 host.

In any case, I still think the SST series have some appeal despite not being as efficient. For one thing, multi xpgs will have a serious problem with throw in such a small host because of the limitations of using such small optics to focus the beam. I'd also assume that it would be easier to attach a single SST emitter directly onto a heatsink rather than 3 XP-Gs without worrying about wiring them in series/parallel or the individual Vf of each emitter. At the very least, the beam will look prettier:nana:.

Still, if wiring the spring to the brass would prevent the spring from warping, then perhaps the problem would be heat after all? Looking at the switch again, the melted plastic seemed to be around the bottom of the spring but also around the small piece of metal that seems to have no other purpose than to secure the spring in place and has no direct connection to the internal components. There is a piece of metal at the end of the spring that seems to link to the internal mechanical switch that turns the light on and off, and the plastic around that piece seems perfectly solid. So if I'm right, most if not all of the heat is being generated by the spring and essentially "trapped" there while the light remains on.


So a nice hunk of thermal epoxy on the bottom of the spring leading to the brass ring ought to do the job.

Do we have a yay or nay regarding this:duh2:?

 

[Justin Case]

Based on my inspection of the switch, it looks like it works in the following way:

1. The tail spring (on the far right) is held in place mechanically by a metal "strap" that holds down the bottom turn. Two curved legs on the ends of the "strap" hook into the plastic switch body to secure the works.

2. The end of the spring makes mechanical/electrical contact with a metal tab (#3 in the photo above). This is the location that you seem to want to solder.

3. When you press the tail button, plate #1 is pushed upward and contacts #2 and #3 to give you momentary-on operation. If you push harder, then the switch clicks and latches for constant-on operation. #2 is also in electrical contact with the screw-on retaining ring. Since the ring is grounded to the tail switch shell, the connection between #2 and #3 completes the circuit and the flashlight lights up.

Excessive heat has to be due to resistance heating (essentially, a toaster). If the localized heating really is at the tail spring, then perhaps just soldering the spring contact to point #3 will solve that. This seems to be the simplest thing to try first.

However, you also have the switch contacts between #1 and #2 and #1 and #3, as well as the small internal springs. As mentioned before, reducing the tail spring resistance may transfer the problem to any of those internal components.

For the McClicky for which you attached some copper braid between top and bottom of the tail spring, did you take the switch apart after it failed to diagnose the failure point?

 

[flashfiend]

If your emitter is bluing, I think a bigger concern is heatsinking for the LED although your McClicky melting is a problem as well. A big reason why Moddoo's drop-in works so well is that wonderful P60 heatsink he uses. Hopefully VanIsleDSM's project can accomplish something similar. Although I am anxious to see what Moddoo's been hinting at next. Your Milky project seems interesting considering the quality of the product that comes out of his shop.

In my opinion the Nite Finned Head is a minimal thermal solution at best. A majority of that heat needs to be drawn away from the base of the emitter.

How much current is your sst-90 pulling from your IMR again?

 

[Billy Ram]

My ROPs run at almost 5 amps @ 8.5V and my M@G85s run at just under 4 amps @ 12.6 Volts. I have run both types of lights for extended periods (15+ continuous minutes) without damage.

They won't last long with the 5.5a. @11.5v. the FM1909 draws.
Billy

 

[Noctis]

If your emitter is bluing, I think a bigger concern is heatsinking for the LED although your McClicky melting is a problem as well. A big reason why Moddoo's drop-in works so well is that wonderful P60 heatsink he uses. Hopefully VanIsleDSM's project can accomplish something similar. Although I am anxious to see what Moddoo's been hinting at next. Your Milky project seems interesting considering the quality of the product that comes out of his shop.

In my opinion the Nite Finned Head is a minimal thermal solution at best. A majority of that heat needs to be drawn away from the base of the emitter.

How much current is your sst-90 pulling from your IMR again?

Moddoo's next work probably won't have as much raw power as his Triple XP-G(given the efficiency of the XPG), but so long as it throws well and pulls as much current as possible without melting the switch down like I did, I'll bite. I only hope the notice will go up when I'm at home and not stuck at work or sleeping.

Milky seems to be pretty swamped, so getting my light before July would be overly optimistic, though heatsinking ought to be superior since he's making the module specifically for my light, rather than as a drop-in for P60 lights. I think the main difference would be that the light has 2 modes(high/low). I'm not sure what material the heatsink will be, but considering the expected price, I'd say it would be complete overkill.

My multimeter reads 6.5A from a fresh IMR, which can go up to 7A when the emitter heats up. If the switch has less resistance than my test leads(18 gauge, 3 feet), the draw could be even higher.

The finned head is probably better for a lower current draw or a module with a good heatsink. I'd imagine it would be a great natural pair with Moddoo's heatsink.

For the McClicky for which you attached some copper braid between top and bottom of the tail spring, did you take the switch apart after it failed to diagnose the failure point?

No, I had thrown the switch away.

My current "patch" consists of a slight solder of the spring to the metal strip and applying AS5 around that area to the metal ring below it. The thermal grease doesn't seem to create an electrical path, as my light remains off with the tailcap tightened. The spring still warped, but the plastic didn't melt. However, that might be because of the reduced current flow because one of the soldered wires broke off of the spring on the module, reducing the current to 5A off a fresh IMR cell.

I'll try again with the thermal epoxy tomorrow when I get more switches in.

EDIT:
Tried another test after I resoldered the wires(2 strands seem to be the magic number). The spring warped like you wouldn't believe, but the plastic components are still rock solid. I'm hoping a more thorough patch with the thermal epoxy will have better results.

 

[Noctis]

Seems like the same result with epoxy as I got with AS5. The spring will still warp, but the plastic components seem to be fine.

I'm not sure what a dead skunk smells like, but I suspect the burnt epoxy is giving off a similar odor.

 

[bullettproof]

I have been playing around with the SST90 D36 dropin which is DD. I have been able to get as much as 5.5A out of it doing some tricks. I must say that this dropin is only good for upto 4A of current anymore and the light will start to loose OTF Lumens from heat issues.If you use Copper Tape or Arctic Silver Im sure it would help.Your wasting time and energy trying to get more lumens from a light that cant handle the heat. At 3.2A the highest bin SST90 is 1k Lumens. My suggestion would be to get a D36 refflector and host it is a night and day difference from the D26 setup.

My conclusion running a FM D36 Host and 1x26650 battery is the light works awesome between 3.5A-4A .
__________________

 

[Noctis]

I have been playing around with the SST90 D36 dropin which is DD. I have been able to get as much as 5.5A out of it doing some tricks. I must say that this dropin is only good for upto 4A of current anymore and the light will start to loose OTF Lumens from heat issues.If you use Copper Tape or Arctic Silver Im sure it would help.Your wasting time and energy trying to get more lumens from a light that cant handle the heat. At 3.2A the highest bin SST90 is 1k Lumens. My suggestion would be to get a D36 refflector and host it is a night and day difference from the D26 setup.

My conclusion running a FM D36 Host and 1x26650 battery is the light works awesome between 3.5A-4A .
__________________

The D36 reflector would only have an impact on the beam profile for the most part. Unless the emitter is mounted directly onto a heatsink rather than an empty pill, I doubt the difference in hosts will help much other than with a different battery that sags less.

From what I can observe:
Emitter directly onto heatsink is the #1 most important factor in making efficient use of higher current.

Sadly, nobody seems to be doing any mass production of heatsinks. It would be like a Britelumens heatsink for Mags, but for the P60 instead. Moddoo's Triple drop-in proves its effectiveness, but I guess that's like comparing apples and oranges. I'm not even sure it's necessary to have a gigantic heatsink like the Moddoo drop-in. Even a simple pill but with solid metal instead of empty air will do fine.

Not sure if thermal epoxy in the pill helps much with the heat.

Looking at my switch and that godawful smell coming out of it, I don't think the thermal adhesive was ever meant to transfer that much heat in that short a timeframe.