Firstly. POLARITY!! If the inner pin is supposed to be + for example, putting it the other way round could be expensive. It would probably be protected, but I wouldn't count on it.
My feeling is that the available current of some seven times less than required, would probably just gasp and never give a trickle. But with electrickery, you never know. Putting it on the higher voltage would rely on the laptop loading it down to 'whatever voltage'. Sometimes works, but very norty.
Probably better to do the smiling and asking thing
<< but not quite like that.