|All bases: By lithium internal battery. Backup duration is approximately 30 days (typically) at 25°C (77°F) after battery is fully charged. It take 15 hours to obtain 0 to 90% of the full battery charge. Battery life is 10 years when charged for 9 hours and discharged for 15 hours. The battery cannot be replaced.
40DRF compact bases: By user replaceable lithium external battery (in addition to internal battery onboard). Backup duration is approximately 3 years (typically) at 25°C (77°F) under normal operating conditions of the base (typically, no long-term powering off of the base). BAT LED on front-panel provides indication of battery power status.
Note: The Twido was obsoleted 12/31/2016 and was replaced by the M221.