Zte G R621 User Manual page 26

performance, it is recommended that you first use up the battery power
and then charge it completely. A new battery's full performance is achieved
only after three complete charge and discharge cycles.
1. Connect your travel adapter to the right of your mobile phone as
shown in the diagram.
2. Connect the other end of the travel adapter to the mains socket.
3. When the battery is fully charged, disconnect the charger.
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