Nokia 9290 User Manual page 29

Battery operation time is affected by the following: whether both the phone and
the communicator interface are on, radio signal strength, various phone settings,
and the length of the screen blanker period.
It is always recommended to keep a charged battery in the communicator. Keeping
the battery charged maximizes the lifetime of the backup battery supplying power
to the real-time clock of the communicator. In case the backup battery is drained,
it will be automatically charged the next time a charged battery is reconnected to
the communicator.
Always close the device cover before removing the battery. Closing the cover will
save all data.
Note: The battery does not fit into place if the SIM card is not correctly installed.
Do not force the battery into place! Check that you have inserted the SIM
card as described in the Getting Started Guide. If the SIM card is incorrectly
installed, remove it by pulling it out of the slot, and insert it again.
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