I didn't think of it yesterday, but drills have brushes, so should run on
AC. If there is a problem, it will be with the speed controller, which may
or may not accept AC. If you are willing to gamble, connect the drill to a
small battery charger, naybe 10A, and give it a try. Observe polarity.
The trouble with chargers is that they tend to go way up in voltage with no
load, possibly damaging the speed controller. For full power, you may need
a bigger charger. This is unfiltered DC, so if the voltage isn't too high,
it should work.
If you have a 12V transformer, that will supply unrectified AC and polarity
will not be meaningful..
Remember, this is an experiment. It's your drill!