"a1esta" writes:
Most manufacturers will state that the life of batteries in terms of
the number of charging and discharging cycles. I remember reading from
somewhere that rechargeable batteries has a shelf life even when the
batteries are not used.

Batteries differ. LiIon hold charge for a long time on the shelf, but
they also slowly self-destruct whether they are used or not. They will
have much less capacity in 2 or 3 years even if you only use them a few
times a year.

NiMH are more robust, in that they can last many years if treated well.
They do self-discharge at a faster rate, so if you only use the battery
3 times a year expect to have to charge it *before* using it. NiMH can
also be charged in well under an hour, while LiIon takes an hour or two.

I intend to buy a cordless screw driver mainly for use in driving
screws on cabinets, walls etc. And I will use it only about 3 to 4
times per year. And if the batteries really have shelf life, it would
not be econimcal. Would it be better to get the corded tool instead?

Corded tools have more power and run forever without recharging
batteries. But if you're working where there is no 120 VAC, cordless is
better than the alternatives (gas generator, big battery and inverter).

If you do get a cordless screwdriver, try to get one with an
interchangeable battery pack instead of an internal battery. This lets
you (a) replace the battery easily when the battery dies, and (b) have
more than one battery so you don't run out of power at a bad time.

Dave