Dual-driver setup question

Flashlight Modding and DIY Parts
1

I have a question for the driver experts out there. I am thinking of making a dual-driver setup for a AA sized light, so I can have the capability of a high performance FET for use with Li-ion 14500, or a less powerful boost driver for use with AA cells.

I’m imagining both drivers essentially connected in parallel, with a selector switch (which I will design) that would connect or disconnect the boost driver negative input from the host/cell negative. With the selector switch disengaged, it would just be a FET driver light for use with a 14500. With the selector switch engaged, it will hopefully work as a boost driver for use with a AA cell. The AA voltage will be connected to the FET driver, but will not be high enough to “turn on” the FET driver.

When the selector switch is engaged so that both drivers are connected in parallel, the boost driver output will be connected to the FET driver output. My question is: what happens when you connect ~3.6V to the output of a FET driver? What I don’t want to happen is for current to flow “backwards” through the FET driver negative path, as this would stop the boost driver from working.

My thinking is that if the ~3.6V does not get applied to the MOSFET gate, it should be OK. But I am not intimately familiar with these drivers.

Any insights?

2

There are nice lights with 800 lumens on a 14500 and running on NiMh on 300 lumens like Utorch UT01

The main thing speaking against FET is the amount of heat in such a small light, you can modify a driver of those lights to get more current

3

That output would be acceptable. I need it to be rear clicky switch, as I will be carrying it inside front pocket.

I purchased a trustfire F20, and I plan to put a dedomed XPG2 in it.

4

Can’t help you here, but highly interested in what others will say!

5

I was assuming the boost driver would have the positive from the battery pass through to the emitter, similar to most drivers we use, but this is not always the case with boost drivers. I have a boost driver made for single AA from a cheap sipik 68 clone light I got a long time ago. It has the negative, not the positive, from the battery pass through to the emitter. I tested the configuration I explained in the first post with this boost driver and a FET-only driver (from mtnelectronics). It did not work because when these drivers are connected in parallel the input positive for the boost driver is connected to its output positive. This combination of drivers would work together as long as both input positives are not connected together. This has been very confusing to think about.

Does anyone know if there are boost drivers that have their input positive lead pass through to the emitter? In particular the lumintop single board here: AA / AAA Small Boost Drivers - Various Models & Modes