Audio-Technica ATH-CKS50TW Noise-Canceling True Wireless In-Ear Headphones (Black) - Manual (Page 14)

Charging the battery
13
3
Connect the included USB charging cable (USB Type-A side) to the computer to start charging.
While charging, the four charging indicator lamps light/flash as follows. (It may take several seconds for the
charging indicator lamps to light.)
Charging indicator lamp Status
Flashes/lights in white (the four
charging indicator lamps light or flash
according to the battery level).
Charging
Lights in white for 10 seconds, and
then turns off.
Charging complete
All four indicator lamps flash white
quickly.
Charging error [1]
[1] The charging case or headphones may be hot. Allow the temperature of the product to cool sufficiently before charging in a well-ventilated
place (10 to 35°C (50 to 95°F)) away from direct sunlight.
4
When charging is complete, disconnect the USB charging cable (USB Type-A side) from the
computer.
5
Disconnect the USB charging cable (USB Type-C side) from the product’s battery jack.
When charging, make sure to use the included USB charging cable. The product may not charge with
cables other than the included USB charging cable.
Always make sure the headphones are not wet before charging. The headphones may not operate correctly
or may not turn on if they are wet. Wipe the headphones with a dry cloth, shake them multiple times to
remove any excess water, and allow the headphones to dry thoroughly before charging.
Charging headphones without the USB charging cable
A rechargeable battery is built into the charging case. If you have charged the charging case, you can charge the
headphones without using the USB charging cable.