The Rechargeable Lithium-Ion (Li-Ion) battery is rated at 3.7 VDC and 1300 mA. Depending upon the network configuration, a fully charged Birdy 3G battery can be expected to be operational for approximately 520 hours if used in POCSAG mode only. Using GSM mode drops operational time to about 80 hours. If GPS is also used, that time drops to about 60 hours of operation.
Li-Ion batteries are one of the most popular types of rechargeable batteries for small electronic devices due to their high power, low discharge rate and light weight. Like all rechargeable batteries, however, they do not last forever and deteriorate over time. It is recommended that these batteries be replaced at regular intervals or when pager performance is noticeably reduced.