I tested what I believed to be copper alloy (possibly beryllium copper) springs that I got from Fasttech . The are definitely not steel and according to Fasttech they are made of “carobronze”, a brand of copper alloy alternative to beryllium copper. Whatever they are, they exhibit superior performance over standard steel springs that we often see on drivers and tailcaps.
I also tested similarly sized chrome-plated and gold-plated steel springs that I removed from flashlights or were on some switches I had.
All three were tested at 5A and the resulting voltage drop across the spring itself was measured. The measurement was taken after the voltage settled due to any heating of the spring.
Copper alloy spring: 114mV at 5A = 22.8 mOhm, no significant heating, warm to the touch.
Gold-plated steel spring: 301mV at 5A = 60.2 mOhm, spring got very hot and started to smell but no visible smoke.
Chrome plated steel spring: 680mV at 5A = 136 mOhm, spring began to smoke and melted my J-clip before I noticed and stopped the test.
Not exactly definitive or comprehensive, but good enough for me. These springs are only about 12-14mm tall, so not the best for every application. I used three in my Copper DIY build, and I am happy with how they work there.
Copper braid/wire can help all three types, but there is a point of diminishing returns, so I only recommend augmenting the spring types that get all hot and bothered if you do not do it.
I de-soldered the driver spring first, and then tried to solder it back with the copper braid attached......
That wasnt much fun... and it took me quite some time, and it doesnt look good, plus the copper braid got quite a bit of solder in it, so it isnt that flexible anymore... hopefully it will hold up.
Get this - for my Shocker mods, I'm like copper braid'n every freak'n spring, five, and getting good results with higher recorded amps. Well, one of my Shocker customers accidentally shorted the + to - while attempting to measure amps, I think, so, he said the lan on one end of the carrier burned up. He patch'ed it, and got it fully working! But, that got me think'n -- the weakest point of a circuit will burn up on a short, so, those lan's are the weakest point - pretty obvious? So on my latest Shocker build, I added jumper wires over the lans - there is one on each end cap on the underside - longest run lan. So I had a shocker carrier with the extra jumpers, one without - measured amps on Pana PD's with the IOS 3.5A driver (runs direct drive on a Shocker), and got 0.35A higher on the jumpered carrier (4.35 to 4.7A).
So, jumpering the lans made a real measured difference, amps correlate to lumens pretty well on XM-L2's on copper. Crap - on Samsung 20R's, I'm getting over 5 amps, over 4,500 lumens at 30 seconds, 223 kcd, without the jumpered lans - sic...
I think he means the traces between the contact points for the cells. I know what he means because I did the same thing (shorted right inside the flashlight, smoke everywhere, scared the daylights out of me). I ended up bridging it as well.
I didn’t go back and do the others, but now I’m thinking I should.
On a small light, like the SK68, the currents are still quite high (1.5-2A). There could be a benefit to improving the resistance path. I would be concerned with using 14500 Li-Ion cells though, as I think the resistance is what keeps the driver from blowing up.
If you only use AA Alkaline or Ni-MH, go to town; Li-Ion 14500, not so sure it is safe for the driver. Only one way to find out
Thanks for posting your results. They are very encouraging. Have you had a chance to compare the FT copper alloy springs with similar beryllium copper springs? I wonder if there would be significant differences?
Last night I was messing around with resistor modding some new drivers I got for the BTU Shockers... I had one up to 7+ amps on 3 20R cells, settling down to 6.9A. The carrier springs were getting VERY hot after only a few seconds. They definitely need to be upgraded and/or supplemented with copper braid to handle that much current. I may be interested in some beryllium springs after all.
The FT copper springs do conduct well but mine have not held their shape well at all. I won't put them in lights anymore because after only a few battery changes they are pretty flattened out.
I still have some of the FT 134700 Springs if you'd like to try some. PM me and I'll get them sent your way, I just wasn't that impressed with their qualities as a spring (although they were a good conductor). As always, they could vary the quality/manufacturer from time to time so what you get when if order today may not be the same thing that I got.
I didn't replace any of the springs in the Shocker carrier, I used the FT springs on a few other personal lights back in October. I have since had to replace them all. I should have taken a picture but they were pretty flat when I took them out!
Thank you for the kind offer… thats very considerate of you. I just put in another FT order and included a few bags of these springs. The reason I asked you how they were used was to give me an idea of the amount of compression they were subjected to. It sounds like they werent resilient enough, regardless of where they went. I might play around with a blowtorch the next time I change the oil in my car and see if I can put some more tensile in them (heat and quench in oil), but I suspect the results wont be very impressive.
Ive become pretty good at wire modding my springs, but a good copper spring would sure take a lot of the work out of high volume mods for others. Im sure you had the same idea in mind.
I was considering removing coils and rebending to keep compression around 40% and about 60% on longer protected cells. I’ll play around with them once they arrive and see what I can come up with. Amazon carries a ton of beryllium springs but they cost a fortune. Nothing I could find on digikey or several other searches. Im not sure why these are so hard to come by in small quantity.
