Honda 2003 Civic Hybrid Owner's Manual page 217

Battery
Charging the battery with the cables
connected can seriously damage your
car's electronic controls. Detach the
battery cables bef ore connecting the
battery to a charger.
218
Maintenance
If your car's 12 volt battery is
disconnected or goes dead, the IMA
battery level gauge reading may not
be correct the next time you turn the
ignition switch to ON (II). It may
show less than the actual level
temporarily. It will show the correct
level after you drive for at least 30
minutes.
If your car's battery is disconnected
or goes dead, the audio system will
disable itself. The next time you turn
on the radio you will see ''
in the frequency display. Use the
Preset buttons to enter the five-digit
code (see page 137 ).
When the battery is disconnected,
the clock setting in the audio system
will be canceled. You will need to
reset the clock according to the
instructions of the audio system.
''