Large BP Spring:
Material choices: BeCu C17200/Phosphor bronze C54400
Spring upper diameter: 6,00mm
Spring base diameter: 9mm
Spring thickness: 1,0mm
Spring height: 13,00mm
Total number of coils: 5
Plating: Copper(50um)+Nickel
The main advantage of using phosphor bronze would be much lower cost, with 1/2 the conductivity of BeCu C17530 and slightly better mechanical properties.
The main advantage of using BeCu C17200 would better mechanical properties by a nice margin, at a slightly lower price than BeCu C17530.
@djozz, why would you want a lower performing(electrically) spring?
Do you plan on using those as a support for a bypass if it ever fails?
Just because I know that when going budget, the electrical performance would go down anyway, it was a way of saying that it is not a big problem to me. Reason is that many of my current favourite leds are so low voltage that maximum spring conductivity is not important anymore, 3 times better than steel is way sufficient.
BlueSword, I apologize if you’re already aware of the latest in the FW3A emitter choice saga, but just in case your experience looking for good bins of SST-20’s can be helpful to that team, you might check out Toykeeper’s latest update in that thread:
Yeah, the last time they broke a piece of special glass with Be, a team came to decontaminate the room.
Imagine I lend or sell my Q8 with BeCu copper springs, the guy remove the battery, put it back but with one battery reversed = short and then one spring goes “poof”…magic powder. No thanks.
I don’t want to have to keep track of which of my flashlights have BeCu springs. I’m fine with springs bypass or springs with a tad higher resistance. I don’t seek maximum lumens anyway.
The risk is negligible, especially since the springs have much higher conductivity, but a 0,0001% risk still does exist.
Still, in a dual spring array, I’m always worried what would happen to the cell inside of a light that would be shorted. A dual spring setup will not fail easily in a short, especially if compressed.
I’m more worried about a cell catching fire than BeCu finding its way into the air.
The day someone manages to vaporize a BeCu spring, they’ll just tell me.
BTW, copper powder is still very harmful if inhaled or blown up, as copper oxide power is quite reactive.