Hate to ask, but which cord did you cut, AC side or DC side?
On the DC side
White = +ve voltage
Black = 0V (ground)
Blue = Sense - feeds EEPROM in laptop to control charging (approx. 1.5V when laptop is charging - likely very close to the white wire voltage when not plugged into laptop).
If your plan is to use the DC voltage to power a DC input Lipo charger, 65Watts is only going to give you approximately 3.4 amps (Power = Voltage x Current)....not a lot to play with when charging Lipos. If that is enough current, use the black and white wires, cap the blue sense wire.
However, I also suggest that you grab a DVM and test the lines for your self. Better safe than sorry.
As Bricks mentions server and/or desktop power supplies are a good source for doing what you are looking into, more Wattage - more current for charging. (a 450 Watt supply would give you about 30Amps at 12 Volts good for up to 3 cell lipos, put 2 in series for 24 Volts 30Amps and good up to 6 cell)