Can I use cell phone batteries to build battery pack?

[dmprok]

I have several cell phone batteries (same) and they are Li-Ion 3.7v 1300+ Mah. I've read somewhere that you're not supposed to charge it with hobby charger and it's bad idea to connect them in serries. I tried charging at 1A and battery remained cool, I had to stop the charge prematurely, but it seems like there is no issue with charging via my Thunder AC6. I've took one apart and I see it has protection circuit on it, I am not sure if it's designed to function same as protection on 18650's, but I did see it work when I tried to put a load of around 2A, my light didn't work, so I bypassed it and it worked, I also tested at at 1.8A it does work with prection circuit. The small size of this battery and rectangle flat shape makes it very attractive for cetain applications.

My question is, can I put it in series and charge it as 2 cell via hobby charger? Also is it possible to balance if I add my own wiring? Does anyone have diagram for balance wiring 2 cells? I can think of many uses for it, one of them being external battery pack for my video camera.