Sennheiser MX W1 Instruction Manual page 19

Replacing the earphones' rechargeable batteries
CAUTION! Danger of damage to the devices!
Rechargeable button cells from other manufac-
turers may cause damage to the earphones and
will invalidate the warranty.
~
Only use rechargeable button cells recom-
mended by Sennheiser (see page 22) .
.. Slightly
lift
the end of the caps and slide the caps out of the
guide rails.
.. Insert the new rechargeable batteries as shown. Observe
correct polarity when inserting the batteries.
.. Replace the caps and slide them onto the guide rails until
it clicks audibly.
.. Charge the earphones until the corresponding LEOs go off
(see page 8).
Note:
The battery caps are designed to fit tightly into the
earphones in order to avoid losing the battery and cap should
the earphones fall off. Do not open the battery caps unless
the battery needs to be replaced.
18