Sennheiser NoiseGard HMDC 322 Instructions For Use Manual page 51

2. Connecting the headset to the battery pack
(except HMEC 302, HMEC 305 and HMEC 306)
The NoiseGard™ electronics of the HMEC 300, HMEC 305-C, HMEC 322, HMEC 400 and
HMDC 322 headsets can also be powered via the BP-03 battery pack (u 'Recommended
accessories'). The battery pack can be operated either on standard or rechargeable
batteries (not included in the delivery). However, to ensure a longer operating time, we
would recommend using standard AA size alkaline manganese batteries (IEC LR6). If
operated on rechargeable batteries, the operating time will be reduced to approx. 3
hours.
Inserting / replacing the the batteries
Open the cover of the battery compartment.
Insert four AA size alkaline-manganese batteries (IEC LR6). Observe correct polarity
when inserting the batteries.
Close the cover of the battery compartment.
LED operation and battery status indication
The battery pack has two control LEDs.
Green LED: The battery pack is turned on and the battery capacity is sufficient.
Red LED: The batteries are low. Replace the batteries.
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