Powertools seem to be either cordless (with unwieldy batteries) or plugged into the mains.
Today’s invention is a drill (or whatever) which makes use of the fact that most jobs don’t benefit much from being free from a powercord.
It consists of a power lead with a small cordless battery on the end. This plugs into the tool during normal usage (when the battery is also being charged).
When the need arises, the cord can be detached leaving the small (and therefore light) battery available to drive the device for the short time necessary.