first, welcome to RCUniverse!
second; STOP WHAT YOU"RE TRYING!!!!
that is absolutely a Lipo battery and will explode, catch fire, and do all sorts of other horrible things if you try and charge it with anything other than a charger designed to charge lipos.
you should be able to tell how many cells by simply counting them if you can, if not then count the pins on the balance plug. the plug will have ONE additional pin than the pack has cells.
(4 pins = 3 cells, 5 pins = 4 cells, etc)
do a balance charge at 1000 mAhs for however many calls the pack has.
the pack is likely a 3800 mAh or 3.8 amps.