mixing protected and unprotected LiIon cells?

[wquiles]

I am still learning what is safe and not, and I am wondering what happens if you mix LiIon cells, some protected and some not.

I would imagine that if I have a Pila 168S and a 18650 un-proteced cell in series (say in a 4xcell body like the M4) both cells would loose charge as the light is used and eventually the protected cell will stop working due do its protection circuitry.

The question is, how does the protected cell stops working? Open circuit? If this is indeed the case, then one protected cell is all I need as it would protect both cells, right? Am I missing something?

Will

 

[cy]

18650 will not fit into M4, unless you bore it out.

don't know what the proper proceedure is, but I've been using 2x 18650 in 2C m*g Nflex with one cell being a 168A. the other is bare li-ion.

one discharge protection will stop a dead short in a series. been toying with the idea of making a fusible link in multi-cell li-ion packs.