The following factors affect battery life:

Prolonged use at extreme temperatures (close to the limits of -20 °C and +60 °C (-4 °F to 140 °F) will shorten the life of the battery.
Over-discharge of the battery will shorten the life of the battery. Always fully recharge the battery when it is low or at least every 6 months, whichever comes first.
Never leave the instrument in storage with the WiFi™ set to periodically connect.