C. Using the Built-in Battery
The unit has a built-in, non-replaceable, rechargeable battery. Charge the built-in battery before using it for the first time. The normal charging time should be completed within 4-5 hours.
The green charging light will go out when the built-in battery becomes fully charged.
To Recharge the Built-in Battery
WARNINGS:
•The built-in battery should not be exposed to excessive heat such as sunshine, fire or the like.
•The built-in battery present a risk of fire or chemical burn if mistreated. Do not disassemble, heat above 212°F (100°C), or incinerate.
•Dispose of the unit with used built-in battery properly, environmental problems must be considered and local rules or laws governing the disposal must be strictly followed.
CAUTIONS:
•The built-in battery can only be recharged when the unit is in CHARGE mode while using the AC adapter.
•The built-in battery cannot be recharged when the unit is in power ON mode.
•Do NOT recharge the battery in the vehicle by using the car power adapter.
•When the built-in battery power is low, 
will display on the screen and the unit will stop playing.
•Recharge the built-in battery when you are ready to use it again.
•While using the built-in battery, the environmental temperature should be 41°F (5°C) to 95°F (35°C).
•To get the longest service life of the built-in battery, charge at indoor temperature.
