Sennheiser FLX 70 Instruction Manual page 6

Do not heat above 40 °C (104 °F), e.g. do not expose to
sunlight or throw into a fire.
Do not expose to moisture.
Do not short-circuit.
Do not mutilate or dismantle.
Store the units/re-chargeable batteries in a cool and dry
place at room temperature (approx. 20 °C).
Only charge rechargeable batteries with the appropriate
Sennheiser Communications chargers.
When not using rechargeable batteries for extended peri-
ods of time, charge them regularly (every six months for
about 1 hour).
Only charge rechargeable batteries at ambient tempera-
tures between 10 °C and 40 °C.
Do not charge the rechargeable battery if the unit is obvi-
ously defective.
Return defective units or units with defective rechargeable
batteries to your specialist dealer.
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