Model Forum / Radio Controlled / Land Models / January 2008

Hi - forgive me I'm a mechnical guy with limited electrical knowledge.: )

I noticed cell phone batteries have small circuit boards at the end of the
pack.  What is the purpose of the board?

I am being tasked with a project using arrays of larger lithium cells - I
think there are 12 per pack.  Each array comes with a circuit board at the
end as well.  I noticed on the circuit board there looks to be a small
buzzer or something?  Am I correct in seeing that?

If I wish to disassemble the packs to make larger arrays - could I have a
circuit board built to handle the larger array?  Or is it more advantageous
to have a bunch of smaller arrays/packs than one large one?

Lastly, are battery packs assembled in series or parrallel and what is the
thining behind one over the other?

Any help appreciated -