250 Lumen Cree R2 "Drop-in" for the M3

[Thundar]

Man, this is becoming much more complicated than I had first anticipated.

Will one of these spacers on the lighthound site would work?

Magnetic Spacer for Charging 1/4" x 1/4"
http://www.lighthound.com/Magnetic-Spacer-for-Charging-14quot-x-14quot_p_1047.html

Or

Magnetic Spacer for Charging CR2 or 14250 Battery (1/4" x 3/8")
http://www.lighthound.com/Magnetic-Spacer-for-Charging-CR2-or-14250-Battery_p_1048.html

I am concerned that the magnetic spacer is so narrow that it will come loose from the battery, go sideways in the body and touch the inner wall.

Are there any other options or should I just order one of each and give them a try?

 

[Thundar]

...figured out the quick reply btw...

 

[Thundar]

For further: I am planning on ordering 2 rechargeable AW/IMR16340 cells along with a dummy 123A cell in the future. Will these magnetic spacers cause a problem with that setup?

 

[donn_]

There's little or no reason for this to be complicated. I indicated in the initial post the spring was shorter than the stock setup, and a spacer was required.

I only needed a 1/16" spacer, and I doubt you'll need 1/4" or 3/8". You can make a perfectly good one, custom fit to your needs, by stacking the appropriate number of metal washers, or even a penny or two. Tape the outside with electricians tape to avoid shorting against the inner wall of the flashlight.

 

[BSBG]

For further: I am planning on ordering 2 rechargeable AW/IMR16340 cells along with a dummy 123A cell in the future. Will these magnetic spacers cause a problem with that setup?

You would be much better off with 2 17500s with the LED module - double the run time.

 

[Thundar]

OK, I tried to tape together a bunch of little metal washers together to connect the circuit and the light flickers on and off... I do love the amount of light and throw of the LED when it does work, however. I am ordering some rechargeables tonight along with a magnetic spacer.

My understanding regarding the three types of rechargeables that I've read about so far is:
AW IMR16340's - put out more light/current than lithium SF 123A's, with a similar runtime (approximately 50 vs 60 minutes). They require a dummy spacer to fit into the same body.
AW 17500's - longer runtime than lithium SF 123A's. 2 take up the place of 3 123A's.
AW 18650 - not really an option for me as I don't want to bore out the body.


2 questions:
1) Will the two AW IMR16340's burn out the LED or cause some other problem due to the high amount of current?
2) Will the two AW 17500's put out roughly the same light as SF 123A's?

 

[Justin Case]

I don't know what kind of magnet you are going to buy, but be aware that the shiny Ni-plated neodymium magnets are very brittle. I've had several break in half just looking at them cross-wise. One broke right in my hand as I was handling it. I personally would not trust them in a flashlight. My belief is that under impact (e.g., dropping the light), these magnets are highly susceptible to fracture.

The IMRs have higher current capacity than the regular Li-ions, and also lower internal resistance. But I doubt either one is an issue driving the LF R2 lamp. You should get the same output using any of the battery combinations listed, assuming the LF R2 lamp is running in regulation.

I'd be surprised if 3xIMR16340s give you longer run time than 3xSF123A cells.

Let's say that the LF lamp driver is 80% efficient. Let's also assume that the IMRs run at 3.8V each under load, vs 2.6V each for the SF123As. If the R2 forward voltage is 3.7V at 1000mA, then 0.8 * 11.4 * Ibatt = 3.7, and Ibatt = 3.7/(0.8*11.4) = 0.4A. In comparison, for the SF123As, Ibatt = 0.6A.

But the IMR capacity is about 500mAh vs 1400mAh for the SF123As, giving estimated run times of 1h15m vs 2h20m, respectively.

It's hard to see a likely combination of variables that would increase the IMR run time by a factor of 2 to surpass the SF123As.

Let's look at the 2x17500 case now: 0.8*7.6*Ibatt=3.7, and Ibatt=0.6A. AW rates his 17500s at about 1100mAh capacity, so you'll get a little less run time vs 3xSF123As. About 1h50m.

 

[Thundar]

I was planning on getting a 1/4" x 3/8" nickel plated neodymium disc magnet from lighthound.

Would a 15mm Charging Spacer made out of Aluminum work?

 

[Justin Case]

Any chunk of metal of the right dimensions will work. Then tape, shrink tube, paint, etc the sides like it was a small battery, to insulate it from shorting against the flashlight body.

 

[DM51]

... I tried to tape together a bunch of little metal washers together to connect the circuit...

Er… this sounds a bit iffy… I wouldn't be too happy with the idea of these metal washers just held together by tape…

I was planning on getting a 1/4" x 3/8" nickel plated neodymium disc magnet from lighthound.

Good quality neodymium magnets are extremely strong. You could have a problem managing one that size.

Any chunk of metal of the right dimensions will work. Then tape, shrink tube, paint, etc the sides like it was a small battery, to insulate it from shorting against the flashlight body.

This is a better idea, although please do NOT rely on paint as an insulator – it will not be safe.

 

[Owen]

2 questions:
1) Will the two AW IMR16340's burn out the LED or cause some other problem due to the high amount of current?
2) Will the two AW 17500's put out roughly the same light as SF 123A's?

1)No. They have nothing to do with the amount of current going to the LED. Unlike incandescent lights that are driven directly by the batteries, this drop-in has a "buck" circuit that controls the amount of current, and lowers the input voltage to that of the emitter. These batteries are not a good choice for most LED setups, with the exception of those with high current requirements that are beyond the ability of standard Li-ion cells of similar size. You will be better off with the regular protected cells, as they have higher capacity in addition to being protected.

If you're using the 6-13V Lumens Factory drop-in with the stock M3 body, I would think your best bet is to use 3 R123 or 2x17500. The total capacity will work out almost the same, but 2x17500 will be more convenient to charge and load, and cheaper to buy.

2)Brightness should be the same, because the drop-in is regulated. Protected 17500s will provide full output until they abruptly cut off as one or both of their protection circuits kick in when the voltage is low enough, though, while 3x123 will run longer then continue to function with rapidly decreasing brightness after falling out of regulation. Same would be true for 3 protected R123s as 2x17500.

 

[Thundar]

Well, early yesterday I ordered 3 different length (1.6mm,1/4",3/8") magnetic spacers, a 15mm aluminum spacer, 2 AW IMR16340's, a 123A dummy and a battery charger (Ultrafire 3.6 or 3 volt).

I ordered the aluminum spacer just in case the magnetics don't work, and I will file it down to an appropriate size and then insulate the sides with electrician's tape. I ordered the 16340's because I like the idea of having rechargeable replacements that I can use in my other lights as well as my M3 (my gun light and Z2).

I will advise how it turns out.

 

[Thundar]

I got the spacers and rechargeables today. Both the 1/4" and 3/8" worked perfectly size-wise. The light still flickered, however. I took the head back off and noticed that the heavier spring (the one that puts pressure between the head and body) was not attached to the LED housing but was floating free. I attached it back on the housing and tried again - SUCCESS! The beam is pretty narrow, but that's fine. I like the throw and intensity of the beam.

My next mod will probably be to my Streamlight SL20X, but not for a little while.

Thanks for all of your help!

 

[Thundar]

BTW, I covered the sides of the magnet with electrician's tape to avoid short circuiting the light. Justin, the 1.6mm magnet broke in half as I was taking it out of the bag, but the 1/4" and 3/8" magnets seem pretty durable. They sure do have strong pulls.

 

[allburger]

Has anyone considered or experienced any heat dissipation issues with this set up?

 

[Justin Case]

Just to update the estimated output of an MN11 lamp when driven by 2xIMR16340, it looks like it could be somewhere north of 380 lumens, based on testing of a P91 lamp:

http://www.candlepowerforums.com/vb/showthread.php?t=233057

 

[TigerhawkT3]

Has anyone considered or experienced any heat dissipation issues with this set up?

+1

What's the thermal path like between the drop-in and the body?

 

[allburger]

I opened the head on my m3 yesterday and have a lumens factory d36 op on order. I guess i can be the test dummy for the heat issues. I guess i ought to be since i asked the question and I'm running the led in there regardless!!!!

 

[Sgt. LED]

Hey fellas!

So far I've not cooked my rig. Thermal path is not great though. I think it takes a bit too long for the head to warm up. I think finding just the right diameter aluminum collar to bridge the gap from drop-in to the head would do wonders but at this point I've not found anything that fits just right. Again so far I have not damaged anything.

It's so easy to swap the emitter I am not really worried about it. I know not everyone is into emitter swapping so the hunt for the solution will continue.

Anybody got any further ideas to bridge the thermal gap?

 

[donn_]

I haven't had any problems either, but I tend to only run this sort of light for a few minutes at a time.

As Sarge said, there isn't much of a thermal path. The reflector is isolated from the head by the foam anti-shock strip, and the pill doesn't contact the body, other than through the spring.

I'm thinking about two solutions. One is to replace the foam with a metal collar. I don't need anti-shock, and it might move some heat from reflector to head. The other is to coil bare copper wire around the pill, so it contacts the inside of the body. This would essentially replace the spring, and provide both current path and thermal path.