When it is time to replace the battery in your Qolsys QS5210-840, you will see an alert on your system panel.
Follow the instructions below to replace your battery and clear the alert from your system. The QS5210-840 carbon monoxide detector requires a CR123A 3-volt lithium battery, which can be purchased from Indiana Alarm, local hardware store, mass retailer, or battery store.
1. Twist sensor counter-clockwise to remove from base.
2. Remove and replace the CR123A 3-volt lithium battery.
3. Align over the baseplate, and twist the sensor clockwise to reinstall.