On Mon, 17 Dec 2007 15:27:50 -0500, Terry
wrote:

I have seen charging instructions that say to fully charge the battery
before first use.

A friend of mine just bought a cell phone. He took it home and
plugged into the charger and went online to activate it. He never
once looked at the manual.

I tried to tell him he should charge the phone fully first. He said
that only applies to devices that only work on battery only. Because
he had the phone plugged into the wall that it was ok to use right
away.

Who is right?

Your friend.

Most all cell phones use a lithium ion rechargeable battery. You
are told to charge it first so that your phone is more than just a
doorstop. Plugging the charger in and using the phone is perfectly
acceptable. The phone draws off the charger and not the battery.
This will not harm the Li-ion battery. The battery will just have to
wait its turn.

For cordless house phones the story is different. They use Ni-Cads
normally and sometimes NIMH batteries. They should be charged
fully after installation especially with the Ni-Cads. This full
initial charge is the best way to insure that the battery conditions
itself to accept full charges.