Screwdriver Adaptation

As you all probably know an electrical capacitor has the ability to be charged and hold this charge, when the circuit is closed the capacitor will then ‘dump’ all of its charge in a relatively short space of time. I was recently doing some DIY and being lazy using a cordless screwdriver which was great until it came to the last turn or so of the screw when the screwdriver would just grind to a frustrating stop, so my idea is to use a capacitor in conjunction with the motor, which would slowly draw current from the battery, and then as you are coming to the last turn or so, press a button which causes the capacitor to ‘dump’ its charge on the motor giving it that extra bit of power it needs to drive the screw right the way in. I know anybody who knows their components is then going to comment on the size of capacitor needed for such a job, after all a one farad capacitor is about the size of a can of tuna, depending on the voltage rating. This would hold 1 amp second at 1 volt, as the motor in the screwdriver works on a higher voltage than this, (around 4.7 volts), a 1 farad capacitor should do the job. But if the battery of the screwdriver was changed from the primitive NiCd batteries to a NiMH, which would hold more charge, or even a Lithium Ion Battery to keep the weight down, there’s no reason why this shouldn’t be accomplished. After all within reason the length of the screwdriver isn’t all that important, as any woman will tell you, it’s all about girth.