The Stethoset transmitter uses smart charging to keep the rechargeable batteries at the right level and help them last longer.
Charging temperature
Only charge the batteries when the temperature is between 5°C and 40°C (41°F to 104°F). Do not charge outside this range.
Long-term storage
If storing the stethoset receiver for an extended period, ensure the battery is at least 50% charged before storing. Keep it in a cool, dry place.