What is the typical life expectancy of rechargeable batteries?

Typically, a fully charged rechargeable battery (Part #: RF16 or RF46) should be able to power a module for approximately ten days under normal conditions (20°- 40°C GPM settings of 60-second Live Interval and one valve opening sequence per hour.) 

As the live interval is shortened and with more rapid valve openings (based presumably on a higher gas production rate) the battery's lifespan will be diminished. Colder temperatures will also diminish life expectancy. Although modules will function properly at lower temperatures (system operating temperature range is 5°-60°C), the rechargeable batteries will require more frequent recharging under these conditions. The 10-day estimate is based on having charged the batteries for at least three hours using the 10-Station Battery Charger (Part #: RF25) to a voltage of at least 6.7 volts. This should always be done before commencing a study. Voltage can be tested by plugging the battery into a module and checking the voltage on the GPM software screen. Note that rechargeable batteries will lose charge when not being used.

When running the system, remember to check the battery voltage several times daily and change the battery pack when the voltage decreases to less than 6.3V (in the GPM software, a module's voltage cell will be shaded YELLOW under these conditions). Changing the battery pack during the run will not affect test results.