Apple PowerBook (Duo 270C) - Manual (Page 107)

You can continue to use the computer while the battery is
recharging. Using the computer does not affect the amount of
time it takes the battery to recharge.
If you recharge a fully depleted battery with the computer in sleep
or shut down, it usually takes a little over 2 hours to bring the
battery charge to 100%, but the time may vary depending on the
PowerBook you have and the battery you are recharging.
Recharging in a recharger
A battery recharger and additional batteries are available as
options for your computer. If you purchase a recharger and an
extra battery, you can charge one battery while you use the other,
so you always have a fully charged battery on hand.
The recharger can accommodate two batteries. The battery slots
work independently, so you can put batteries in or take them out
at different times.
The recharger must be plugged into an electrical outlet to charge
a battery. You can plug it in using the power adapter that came
with your computer, or you can purchase an additional (identical)
power adapter from your Apple-authorized dealer.
s Warning: Do not use any other type of power adapter with
the recharger. Doing so may damage the recharger, the power
adapter, or both.
s
Chapter 6: Power Management 91