Series is when individual cells are connected + to - like a 6-cell NiMH pack or flashlight and this creates a cummulative voltage increase with no change in capacity; i.e.- a Lipo cell has 3.7 volts... 3 cells in series (3S) is 3.7V x 3 cells= 11.1V per pack.

Parallel is when individual cells are connected + to +, - to - and this creates a cummulative capacity increase with no change in voltage; i.e.- 2 cells of 2500mAh capacity wired in parallel will be 3.7V and 2 x 2500mAh= 5000mAh capacity.

Lipo chargers are only concerned about "series" numbers so that the appropriate voltage is used in the various cut-offs the charger is programmed with. So a 2S pack will charge at the 7.4V setting, 3S at 11.1V, and so on. The Capacity is used to establish charging current. A 1C charge on a 5000mAh pack will be 5 Amps (5000 milliamps equals 5.0 Amps equals 1C, 3600mA equals 3.6 Amps equals 1C for a 3600mAh pack), a 2C charger would be 5.0 Amps x 2C= 10 Amps on a 5000mAh pack. Most battery manufacturers recommend a 1C charge, but some higher end batteries will acommodate as much as 2C which requires a pretty powerful charger on large capacity packs. Parallel cells do not change the settings on the charger, only the overall capacity.