Maglite C Cell LED heat sink, old style switch

I read through a number of threads about Maglites Drop in LED replacement. There appears to be a heat related problem with the LED replacement. I guess there is no place for the heat to bleed off the LED. The result of this is a drop in power, brightness after a period of run time. I happened to have a Maglite 2 C Cell around and decided to take a look at the set up. ( the D Cell Maglite switches do not come apart ) The heat sink I made started out as a 1 inch piece of 6061 Aluminum. The original piece is some composite material that will act as an insulator. There is one main difference in the piece, I made a flange on the bottom. This is where the tightening ring presses up against the switch when it is put back in the Maglite. That should provide a complete metal to metal contact from the LED all the way to the barrel of the Maglite. This set up allows the LED to 'float' in the switch, the same as the original. I put some grooves on the piece for greater heat dispersion.

The picture shows the piece and the original - and - yes, that is a regular bulb in there. I wanted to be sure I could do this before I buy the LED replacement.

Re: Maglite C Cell LED heat sink

Very interesting solution :goodjob:

I would also apply some thermal compound between the metal pieces (not the epoxy kind!), so that you get better heat transfer

Will

Re: Maglite C Cell LED heat sink

wquiles said:

Very interesting solution :goodjob:

I would also apply some thermal compound between the metal pieces (not the epoxy kind!), so that you get better heat transfer

Will

Click to expand...

I had planned on doing that once I get the LED replacement. The one thing I am not sure of - is that thermal compound electrically conductive ? I have used it for heat sinks on the processor chip on computers. It is easy enough to try, if it doesn't work - I can clean it off...

Re: Maglite C Cell LED heat sink

smart idea.. i'm not sure how well the ground strap will work for your heat path but it will be a whole lot better than nothing.. steel sucks the yazoo for heat conduction.. if you replace the steel ground strap with a strip of copper it'll work a whole lot better.. you can probably cut a thin strip of copper and solder it to the ground screw.. it has probably 8x the heat transfer of steel and since you don't have a solid heat path to the body that's be my bet for the best bet.

thermal compounds are not electrically conductive, don't use them.. but using the likes of pro gold will help heat transfer as well as electrical transfer.

Fortunately this is not a 'high power' solution where contact resistance will kill you.. but alum. is not a good contact material.. especially for a sliding contact.. if you could machine the part out of copper or even brass.. your long-term results will be better (i.e. it won't start just 'getting flakey' in a couple years from bad ground path).

-awr

Re: Maglite C Cell LED heat sink

This set up is different than the D Cell switch. The ground strap is not the heat path, it is still the electrical path. I could probably put the thermal paste only on half and still maintain a clear electrial path. The original slug that the bulb/LED is put in is still there, so is the original steel sliding contact. The difference is the outer shell, original plastic is replaced with aluminum.

This switch goes in from the top, then a ring is screwed into the the barrel from the top to hold the switch in.



This picture shows where the ring is on the switch.The stock switch is on the right. This is threaded and screws into a threaded area on the inside of the C Cell Maglite. ( the D Cell Mags have a split ring and are put in from the bottom of the tube ). This ring makes contact with the flange I put in the aluminum piece I made, I have a thermal contact from the LED to the area it is screwed into to the new aluminum replacement to the flange to the body of the C Cell Maglite.




So - I have maintained the original sliding switch contact area in steel. the same focus ability and an improved heat sink for the LED replacement.

Re: Maglite C Cell LED heat sink

oh hell yeah that's a perfect solution in that case.. the metal ring threads in? i think that might be only the old version C.. i think the new ones work more like the D with the screw through the switch.

Put some thermal goo on top of the flange and that is absolutely perfect.

-awr

Re: Maglite C Cell LED heat sink

There is also a screw through the switch..

Re: Maglite C Cell LED heat sink

Have you tested the temp differences between the stock and custom pedastal?


Mac

Re: Maglite C Cell LED heat sink

cmacclel said:

Have you tested the temp differences between the stock and custom pedastal?


Mac

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Ahh - now come the questions - I have no way of measuring the temperature or if there is a change in the supply voltage after a long run time. My humble tools consist of an analog voltmeter and a mini lathe, I can make this stuff and I am sure it is better, I just don't have a method of measuring it.

Re: Maglite C Cell LED heat sink

You can always use the finger meter can't you

Run the light with the stock pedastal for 15 minutes and then touch the LED casing and see how much it burns you.

Than install your modified pedastal and 15 minutes later use another finger (note not the same one) then measure your blisters after 3 hours and 5 minutes


Mac

Re: Maglite C Cell LED heat sink

I suppose he could measure the current draw on the batteries, with and without the heatsink.

when the drop-in gets hot it goes into low power mode and the amount of current drawn will drop.

the longer it stays in on full power the better.

just thought.

regards.

Re: Maglite C Cell LED heat sink

cmacclel said:

You can always use the finger meter can't you

Run the light with the stock pedastal for 15 minutes and then touch the LED casing and see how much it burns you.

Than install your modified pedastal and 15 minutes later use another finger (note not the same one) then measure your blisters after 3 hours and 5 minutes


Mac

Click to expand...

I prefer the back of the hand method - that blisters much quicker - the skin is thinner..

Re: Maglite C Cell LED heat sink

by the way - this is the host it will go in. This is the before the HA 3 is done.



turns out this mag uses the old style switch, This actually worked out better for my heat sink, I was able to change the top part relatively easily.