I am also making a power pack with 3.7/4.3V output and I want to use 2 or 3 old 18650 batteries from laptop. I suspect that these cells are not individually protected. So, should I use just one PCB connecting the common + and - to B+ B- and P+ P- will be the output? Or should I use a separate PCB for each cell and then combine the output of all to one terminal (which will also be the 4.2v charging input terminals)? Thanks.