Generally the way laptops work is they buck the voltage down to an intermediate voltage with fets rated for 30 volts, which blow up at 31-33volts. they run other dc-dc converters off that intermediate voltage to charge/discharge the battery, supply 5, 3.3, 2.5, 1.8, .8-1.4, etc.
The biggest constraint on your netbook is likely 16 volt tantalum capacitors on that 12v input rail, so if you exceed that they will explode.
but other than that it might work safely all the way through 24 volts.