I just finished a simple mod to my Illuma-Lux flashlight I bought from Elektro-lumens. At $30, that light was cost effective, but not impressively bright. Furthermore, it had developed a flickering problem that cleaning the contacts would fix only partially and temporarily.
I resolved to cure the problem by soldering on contacts made of pure silver. I scrounged through my jewelry-making stuff and pulled out a couple of small scraps of .999 fine silver. I put the scraps on a firebrick and melted them until they formed beads, then I let them cool. I hammered them flat on an anvil top and then filed the faces true, which gave me a pair of pure silver discs about 6mm in diameter and a little less than 1mm thick.
I pulled out the tailcap spring and stretched it until it took a mild set for added contact pressure. Then I soldered the first silver contact on without issues. But when I went to tin the spring in the working end, I discovered that it was made of a material that would not "wet" with solder.
In disassembling the head to figure out how best to remove the spring, I found that there was no heat management to speak of for the 1W Star LED inside. It was encapsulated entirely by plastic components, with only a tiny section of the negative lead in firm contact with the aluminum flashlight body. I realized that tipping the positive spring with silver would not fix the most serious problem with the light.
I discovered that the plastic parts were necessary to maintain insulation between the + and - legs of the circuit. So I drilled out the center of the plastic base to which the LED was attached (to .375" diameter), and gave it a .63" dia. by .03" deep spotface.
I then fashioned a little top-hat-shaped silver heat sink/electrode by turning a cylinder .375" diameter and .6" long and hard-soldering it to a hammered-and-filed disc of .625" diameter and .042" thickness. After a little fooling around trying to soft-solder a silver wire onto the edge of the disc (difficult because of that half-ounce of silver slurping up all the heat), I finally hard-soldered the wire in place before truing the disc's face using 600 grit sandpaper on a surface plate. I then installed this piece into the plastic base I had modified, with the smooth disc surface supporting the LED, and the thick trunk replacing the positive contact spring and its housing.
I bent the silver wire around and soldered it to the + pad from which I'd removed the previously mounted tab. I had to add a small piece of heat-shrink tubing to the free end of the negative lead, lest it be able to short to the new heat sink.
The result was a noticeably brighter light with no flickering, and a firmer action on the tailcap button. Even with brand new alkalines, the heat sink did not become uncomfortably hot from 2 minutes continuous running. There seems to be noticeable heat transfer to the top battery, which I expect would be the main heat path under continuous use.
I think I'll be tarting up the tailcap springs in my other lights with silver buttons as well. It seems we expect a lot from the point contacts between steel springs and steel battery terminals. I don't know how much real improvement there is to be had by using a flat precious metal contact, but it sure couldn't hurt.
Chalo Colina
I resolved to cure the problem by soldering on contacts made of pure silver. I scrounged through my jewelry-making stuff and pulled out a couple of small scraps of .999 fine silver. I put the scraps on a firebrick and melted them until they formed beads, then I let them cool. I hammered them flat on an anvil top and then filed the faces true, which gave me a pair of pure silver discs about 6mm in diameter and a little less than 1mm thick.
I pulled out the tailcap spring and stretched it until it took a mild set for added contact pressure. Then I soldered the first silver contact on without issues. But when I went to tin the spring in the working end, I discovered that it was made of a material that would not "wet" with solder.
In disassembling the head to figure out how best to remove the spring, I found that there was no heat management to speak of for the 1W Star LED inside. It was encapsulated entirely by plastic components, with only a tiny section of the negative lead in firm contact with the aluminum flashlight body. I realized that tipping the positive spring with silver would not fix the most serious problem with the light.
I discovered that the plastic parts were necessary to maintain insulation between the + and - legs of the circuit. So I drilled out the center of the plastic base to which the LED was attached (to .375" diameter), and gave it a .63" dia. by .03" deep spotface.
I then fashioned a little top-hat-shaped silver heat sink/electrode by turning a cylinder .375" diameter and .6" long and hard-soldering it to a hammered-and-filed disc of .625" diameter and .042" thickness. After a little fooling around trying to soft-solder a silver wire onto the edge of the disc (difficult because of that half-ounce of silver slurping up all the heat), I finally hard-soldered the wire in place before truing the disc's face using 600 grit sandpaper on a surface plate. I then installed this piece into the plastic base I had modified, with the smooth disc surface supporting the LED, and the thick trunk replacing the positive contact spring and its housing.
I bent the silver wire around and soldered it to the + pad from which I'd removed the previously mounted tab. I had to add a small piece of heat-shrink tubing to the free end of the negative lead, lest it be able to short to the new heat sink.
The result was a noticeably brighter light with no flickering, and a firmer action on the tailcap button. Even with brand new alkalines, the heat sink did not become uncomfortably hot from 2 minutes continuous running. There seems to be noticeable heat transfer to the top battery, which I expect would be the main heat path under continuous use.
I think I'll be tarting up the tailcap springs in my other lights with silver buttons as well. It seems we expect a lot from the point contacts between steel springs and steel battery terminals. I don't know how much real improvement there is to be had by using a flat precious metal contact, but it sure couldn't hurt.
Chalo Colina
