Sure. You have to connect main batterys + to tail cap switch’s mosfet gate, but then you will not be able to screw on a tail cap ;))
You could use one of those proprietary cells with +/- at both ends of the cell. Or you could just feed your switch wire directly into the side of the driver cavity of the light.
Its possible to use gold or at least silver wires and switch contacts to reduce resistance ;)))
A bleeder resistor and a large enough capacitor with diode on the could do the job right?
Yes! :+1: Nice advice if I decide to massacre the lights :laughing: Hmmm? It would be doable in 21700 tube with 18650 bat used…
I have this FET switch from Lexel… This is top switch for single cell FET flashlights… It has zero loss… Problem is that I can’t sell my builds with that kind of switch to my costumers. My costumers once when battery dies will blame me for fail and I got to cover the warranty.
This type of switch(assembling, disassembling) is not a problem for BLF nation but for the rest of the world it is a problem.
So any idea like bleeder resistor and large capacitor Jared mentioned or any other kind of pure hardware would be better solution… But who uses FET drivers any more? 
(except me? :smiling_imp: )
It doesn’t need to be a DD FET light to benefit from a ultra low resistance switch, these new 40W+ boost drivers pull very high amps too.
I’ll breadboard a circuit tonight and see how if my idea works. I must be missing something obvious if it hasn’t been done thus far
Looking forward for that JaredM :+1:
I didn’t have enough components on hand to test it in reality, but i modeled it in circuitlab and it seems to work. This would be for strictly momentary ( non latching ) pressure switches where max continuous on time is on the scale of minutes. The cap drains through the pulldown resistor while on, and to get responsive turn off performance of the fet it needs to be low enough value limits on time to the timescale mentioned. I still want to make a model asap to test in the real world.
That sounds good… Looking forward to see the model and your test 
FET momentary switch is also good for certain linear driver 1x18650 hunting configurations.
Damn cool stuff happens round here…
Optimists 
I know that you could also make it! But only if you want 
A rechargeable coin cell in series with a diode could be another option?
This is mechanical problem , you have to redesign flashlight from scratch. Lumintop FW serie have E-switch in tail cap
This is probably ths best idea. I wonder if a BIOS cell would bea good solution
Bios cells aren’t rechargeable, and they last a really long time, here it should also be the case as long as the pulldown resistor is a value high enough.
For a rechargeable cell see watch rechargeable cells like this one
Anyone know if Lexel is okay? He hasn’t been active in ages
So I finally rigged up something on the test bench using my oooold homebrew FET remote tape switch assembly and instead of the 2032 I used a bleeder resistor, cap, and diode. It worked. As predicted in the modelling software I used, the 10Mohm pulldown and random cap I had (200uF/25V) it lasted about 10minutes on. Switch-off responsiveness was immediate to the hand/eye. I ran a BLF A6 FET+1 driver and 351D with it. I saw 14mV drop across the FET and pcb traces.
I’ll work more on this soon hopefully. I’d like feedback on the ~10-60 minutes continuous on time before the cap drains through the pull down resistor. Releasing and repressing the tape switch restarts the ‘timer’. I figure in an application like mine where I don’t have a latching switch, it’s fine. I’ll never need nor want to squeeze the switch that long anyway.
In reflection of all this, I really think using a non-rechargeable button cell is fine. The cell only drains while on and with fractions of microamps, their shelf life can be a really long time, and it’s simple in it’s own way. I may end up returning to that configuration. Still, I’m never against more options floating around out there
Your finger would probably feel kinda stiff and cramped up after holding down the trigger for 10+ minutes continuously. Sounds like the problem would probably be the user being bad at hunting rather than a fault of the switch at that point.
Most hunters only require 30 seconds to take a shot or two. Maybe longer if you used a pressure switch with an on/off as well like Convoy’s.