Sharp PC-A290 Manual page 37

Removing External Battery Pack
Before removing the external battery pack, turn off the computer or
confirm that the standard battery pack has power remaining. If the
standard battery pack has no power remaining, connect the computer to
AC power; otherwise the computer will be shut down and data may be
lost.
Remove the external battery pack by pressing the buttons on each end of the battery
and sliding the battery off the computer.
3
Close the cover of the external battery port after the external battery pack
is removed.
Checking the Battery Level
You can check the battery level of the external battery pack (in the same way as the
standard battery pack) with the battery indicator. Press the button on the right of the
indicator. The status of the indicator is the same as that of the standard battery. See
page 3-2.
3-6