Panasonic WX-SZ200P Operating Instructions Manual page 18

Charging
Some kinds of batteries may not be fully recharged in just one cycle and the
runtime becomes small. This happens to the batteries which are being used
for the first time, batteries which have not been used for a long (more than
three months) time, and batteries which have been recharged and depleted
numerous times. This phenomenon is characteristic of the rechargeable
batteries. The battery runtime may be recovered to the normal level by
completely charging and then depleting (by using the microphone) the
batteries two or three times.
The charger automatically recognizes the dry-cell battery inside the
microphone to cancels charging, and then the [CHG] indicator will blink.
However, depending on the type of dry-cell battery, this automatic
recognition may take some time and the [CHG] indicator stay lit until the
recognition completes.
Sometimes, when trying to recharge almost-full batteries at very low
temperatures, these may be mistakenly recognized as non-rechargeable
dry-cell batteries, and the [CHG] indicator may start blinking.
The microphones are charged through inductive charging. Because of
inductive charging regulations, the [PWR] indicator on the microphone may
go off multiple times just before charging is completed, but this does not
indicate a malfunction.
Sometimes, when trying to charge almost-empty batteries, these may be
mistakenly recognized as dry-cell batteries, stopping the charging and
making the [CHG] indicator start blinking. If this happens, remove the
microphone from the charger and re-insert it multiple times until the batteries
are properly recognized. If the batteries cannot be recharged despite
multiple attempts, it means that they are completely exhausted and need to
be replaced.
If, once charging is complete, the batteries in the microphone spontaneously
drain, charging will not start again even if the microphone is still inserted into
the charger.
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