Sennheiser HD 1 In-ear Wireless Owner's Manual

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M2 IEBT
Getting started
Getting started
Charging basics
A complete charging cycle takes about 1.5 hours. Before using the headphones 
for the first time, charge their rechargeable battery for a complete charging 
cycle without interruption. 
When the battery is almost empty or when the headphones are being charged, 
the LED lights up or flashes as indicated in the following table and a voice prompt 
announces the charge condition of the battery. When the battery charge drops 
to a low level, a voice prompt asks you to recharge the headphones.
It is recommended to charge the headphones using only the supplied USB cable. 
If you are charging using an external USB-power adapter, it is recommended to 
use an adapter with an output rating of 500 mA or higher.
LED
Meaning
Voice prompt
Battery is almost empty  
(less than 2 % charged)
“recharge headset“
Battery is less than 10% charged 
“below 1 hour play time”
Battery is less than 20% charged 
“between 1 and 2 hours 
play time”
Battery is less than 50% charged
“between 2 and 5 hours 
play time”
Battery is more than 50% charged
“between 5 and 10 hours 
play time“
1.5 h