2GIG Z-Wave Thermostat (CT-100) - Battery Replacement
Oct 02, 2025
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2GIG CT-100 Thermostat Battery Replacement & End of Support Notice
Important Notice: Alarm.com ended support for the 2GIG CT-100, 2GIG CT-30, and GE TSTAT-300 thermostats on May 27, 2018. These models cannot be controlled from the app or website on new or recycled accounts created after that date.
Accounts created before that date remain unaffected. For new installations, we recommend choosing a supported Z-Wave thermostat model.
Accounts created before that date remain unaffected. For new installations, we recommend choosing a supported Z-Wave thermostat model.
Why Support Ended
These older devices do not meet the higher communication standards required for modern thermostat features, such as HVAC safeguards and enhanced comfort options. Alarm.com now recommends choosing a thermostat from its supported ecosystem of smart thermostats.
Battery Replacement for the 2GIG CT-100
The CT-100 is a battery-powered thermostat that requires four AA alkaline batteries. Follow these steps to safely replace them:
- Slide off the bottom cover of the thermostat.
- Insert four new AA batteries, following the polarity marks inside the battery compartment. Insert the negative end first (against the spring), then push the positive end in.
- Slide the bottom cover back on securely.
- Turn AC power back on at the breaker. The thermostat will restart in OFF mode.
Battery Warning: Replace batteries as soon as the Low Batt indicator flashes. Even if it doesn’t flash, replace batteries at least once a year to prevent corrosion or failure.
If batteries fail while the thermostat is off, your HVAC system could stop working, potentially causing frozen pipes, overheating, or excessive cooling.
View Our Smart Home Security & Automation SolutionsIf batteries fail while the thermostat is off, your HVAC system could stop working, potentially causing frozen pipes, overheating, or excessive cooling.
