Sony CDX-GT35U Operating Instructions (CDX-GT35U) Operating Instructions Manual page 3

Note on the lithium battery
Do not expose the battery to excessive heat such as
direct sunlight, fire or the like.
Warning if your car's ignition has no
ACC position
Be sure to set the Auto Off function (page 14).
The unit will shut off completely and
automatically in the set time after the unit is
turned off, which prevents battery drain.
If you do not set the Auto Off function, press
and hold (OFF) until the display disappears
each time you turn the ignition off.
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