Springs!!

What we need is a spring that is composed of a spring steel core with a pure copper outer layer. And the copper layer needs to be more than just a coating. It needs to have some thickness to it. :smiley:

TY :-)

great test djozz! :beer:

(again…)

Yes, I think surface area matters. Usually when braiding, I fill the top of the spring with solder then file flat.

very nice test, thanks for posting this

What I usually assume is that although the contact surface area may be very small, the resitance is also determined by the length of the narrow section. With two flat surfaces touching, that length is so short that the resistance is still negligible. If one surface is bended (the spring) the resistance may be a bit higher but still very low. Bocian, is there any measured data on this contact resistance? (there must be somewhere).

Thanks for the Test! I think steel springs are the best, gold plated or just simply plated. With the braid, (copper or the silver plated stuff), the spring can then be just what it is, a spring and the current will go through the braid. It will also help with heat stress on the spring, so a little longer life span for the spring. Excessive heat really kills those little springs. When you solder the braid on, you can always solder a copper button on top too, for a good smooth contact to the battery.

Hmm, good points OL.

Good call OL

I usually use a hobby file and smooth the solder joint on the braid, I can never seem to make it solder smooth, but a few passes with a hobby file and smooth as silk

Being a bit conservative, are you?

I think that if you are DBCstm, TomE or Vinh, you are right, copper braided (steel) springs are the best for high drain hotrods.

On the other hand, if you are Old Lumens and into beautifully made moderate Nichia 219 mods, a clean looking phosfor-bronze spring like the one I tested is just great and mechanically thusfar it seems similar to steel (nice and stiff and 'springy'). At non-critical currents like 2 or 3 A this spring does help to get more efficiency out of the flashlight compared to steel springs, while copper braiding will not be drastically better but will look much messier.

OTOH OL uses that flashy 9A driver for stuff: Sales thread - Closed

the old dude can crank out some mean hot rods of his own! :stuck_out_tongue:

While we’re both here, can you fill me in on the kinds of problems you’ve run into when soldering to steel springs? EG are there specific springs you had trouble with, was the trouble purely cold solder joints because of the way steel acts, does being plated help, etc. TIA

I forgot that new powerful side of OL , how could I !!

Thanx Again djozz!!

I posted detailed pics (somewhere??) in a BLF thread comparing the cheap stuff to the better grade Chemtronics braid (ex: http://www.techni-tool.com/Top-Brands/Chemtronics-Desolder-Braid). The difference is radical in my opinion in the design, weave, density - it also solder wicks better! I converted from the cheap stuff to Chemtronics, but eventually switched to quality 22 or 24 AWG wire because I feel the wire is still better to work with and holds up better. I've had numerous failures over time of the cheap braid on springs.

Also a big +1 to O-L's post. Most of the time the spring is seems to be 95% of the volt->amp drop of the tailcap - surprisingly the switch's do pretty well, accept the low budget light ones. I don't have hard #'s to back this up - only from lots of testing of hard-wiring around the tailcap assembly vs. stock tailcap vs. copper wired spring tailcaps.

wight, yes

not plated, it takes so much heat to get the solder solidly adhered that it weakens the spring. plated, the plating starts cracking off. I’ve found steel springs have let go of my bypass, usually on the really cheap lights. Pretty much replace springs as a habit now. Been doing that for a while and really haven’t had much trouble since.

Thanks for the testing Djozz. Nice how well your spring compares to the much smaller nanjg spring. It looks like the solder points shorten the effective length of the IO spring more than yours.

I wonder if rather than even trying to solder to the spring one just soldered to a contact plate that sat on top of the spring and solder the other end of the wick or wire to the pcb pad. Use the spring for its compression strength and don’t worry about an electrical connection through it. Also, if using insulated wire is it even necessary to go down the inside of the spring.

A common technique in spring bypass wiring is the wire outside the spring - depends on clearances, pinch points, etc. which method is better I suppose. I believe vinh uses that a lot, think others do as well. An inner bypass wire certainly is more at risk to reduce spring compression, but I try to carefully test that out. I haven't used outer bypass's much - I'll tend to use a 24 AWG wire in smaller diameter springs. I do though try to get the bypass wire soldered to the pad and spring at the bottom, not just the spring. The top soldering is more problematic. I suppose a nice little copper/brass disc to solder would be a better solution - then that disc gets soldered to the top of the spring. So even for a crappy spring, if the disc loosens from the spring, it would hopefully still be dangling over the spring (could be manually positioned) but if the wire holds well, you still got a rock solid electrical connection.

Downside of outer spring bypass's (in my mind??) is if the top solder joint breaks, that wire is really dangling out there. My thinking would be that under compression, a broken connection for an inner wire would still be making electrical contact somewhat - less risk to ground out on something.

I went with double braids on mine… Just sent it out this morning… Goodbye sweet light. I tried DBC method and I couldn’t get the spring to compress enough. I have to try that copper button top OL.

If you have a good electrical path and good copper heat path to the pill, you can go dd without noticeable sag. :slight_smile:

Agree with OL- unless you don’t plan to braid. Intl has the best but like 3 bucks a spring :expressionless: Better come with some boobs

Djozz,

You are hard worker and you are 100% into your hobby...

Glad that you tested that Phosphor broze springs because I new that they are better than original steel springs only by my luxmeter, always 10-15% more brightness when I swap steel with this phosphor bronze guys (they look like a copper to me).

Your custom spring looks excellent. Need that kind of spring with ∅ 10mm bottom base and 11-12mm height. This springs are much more flexible than steel ones and they are battery friendly not pressing pcb so hard as steel. Excellent for single cell 18650 lights up to 3A.They also accepts solder paste better so they can be braided or wire bypassed to if needed.

I tried braiding steel springs with braid and wires(contact and switch) but lux results were same as stock until I tried copper bronze ones. I really don't know what happened but lux number instantly jumps.

I only wish to try beryllium copper springs but no one has this puppies(at least at China stores).

I found some interesting suppliers for copper like springs here: http://www.aliexpress.com/item/Free-shipping-Phosphor-Bronze-spring-for-flashlight-DIY-100-pack/1062864560.html and here: http://www.aliexpress.com/item/10X8mm-Solid-Copper-Spring-For-High-Output-LED-Flashlight-Driver-Circuit-Board/2054366124.html