Apple PowerBook (Duo 270C) - Manual (Page 105)

When you click the lever to the right of the battery gauge, a Sleep
button appears.
You may sometimes find it convenient to put the computer to
sleep by clicking this button, instead of choosing the Sleep
command.
Responding to low-power messages
When the battery charge drops to about 15%, the computer
displays three messages telling you that your computer is running
on low battery power. You have about 10–30 minutes of work
time remaining after you see the first message, so you have time
to finish what you’re doing before recharging.
What you should do
When you see a low-power message, do either of the following:
n
Plug in the power adapter, or
n
Save your work and put the computer to sleep.
What you should know
The first low-power message is a reminder that the battery will
soon run out. Right after this message appears, the screen
brightness dims automatically to save power.
If you continue to work without plugging in the power adapter or
changing the battery, the computer displays a second low-power
message.
Chapter 6: Power Management 89
Lever