MusicMan TWS Bluetooth BT-X39 Manual De Utilización página 15

How to charge the In-Ear piece (charging box)
The BT-X39 has an internal, rechargeable battery which must be
fully charged before used for the first time. It takes you about 2–3
hours to charge the battery full for the first time.
Remove the plastic strip over the charging contacts. Put the In-Ear
pieces into the charging box and close the box to charge. During
charging, the LEDs of the headphones light up permanently in RED.
When the battery is fully charged, the RED LED will turn off.
While charging the In-Ear pieces for the first time you need to
charge the charging box too.
You can charge the charging box either by using a common USB
adapter* (5V/1A) (*not included). When the charging box is fully
charged, all of the four LEDs will turn BLUE.
The fully charged battery of In-Ear pieces has power for up to 2
hours of playing time or up to 20 hours of standby time. When the
battery is running out of power, the RED LED starts to flash every 20
seconds with prompt of "low battery, please charge". This indicates
that the headphone needs to be charged as soon as possible.
Battery display of the charging box
Click on the button on the charging box, you will see the battery
status through the four blue LED. And the display will turn off
automatically after 4 seconds. Four BLUE LED show that the
charging box is fully charged. The fully charged charging box can
charge the In-Ear pieces up to 2.5 times.
Attention: The headphone fits only in one direction perfectly
when put on! So be sure the right side is on the right and the
left on the left!