Can't run a portable freezer on B&D battery station

After two hours in a cooler, the frozen stuff should still be sufficiently frozen, with no additional ice or dry ice. To ease your wife's mind, maybe buy a little container of ice cream; if it's still reasonably firm when you get home, everything else is still frozen too.

(This time of year in Ohio, all you need is a rooftop carrier on your car to keep stuff frozen indefinitely!)