About this replacement
Mitac Mio 728 / 728g — 3.7V Li-ion Replacement Battery
This 3.7V 1700mAh Li-ion cell replaces the original battery in the Mitac Mio 728 and Mio 728g portable GPS and PDA units. Both devices share the same battery bay and voltage rail, making one cell compatible across the pair. Capacity is 1700mAh (6.29Wh), matching factory specification.
- Mio 728 and 728g compatibility: Both models run the same 3.7V single-cell architecture with an identical battery connector and BMS handshake protocol. The cell slots into either unit without modification.
- Bench tested on actual hardware: We cycled this battery through charge and discharge on a Mio 728 unit. The BMS accepted charge normally, held cell voltage within spec at load, and triggered low-voltage cutoff cleanly — no erratic shutdowns or protection trips during testing.
- Data sync before battery removal: The Mio 728 holds active navigation data, recent route history, and application state in RAM powered directly by the main battery. Pull that cell without syncing first and unsaved data is gone. Sync to your host computer or back up to the SD card before swapping the battery.
Why the Mio 728 won't boot after a battery swap
The Mio 728 boot sequence checks cell voltage before loading the OS. A new replacement cell shipped in storage mode may sit below the minimum boot threshold — typically under 3.2V. The device will appear dead even though nothing is wrong with the hardware or the battery. Connect the unit to its charger for at least 30 minutes before attempting a cold boot.
GPS signal dropping or taking longer to acquire after a new battery install
The Mio 728 GPS receiver draws a higher current burst during satellite acquisition than during steady navigation. If the replacement cell is not at a full charge, voltage can sag during that initial draw, causing the receiver to reset mid-lock and restart the acquisition cycle. This shows up as a long "searching for satellites" screen or repeated signal loss shortly after it locks. Charge the battery fully to 4.2V before taking the unit out for navigation.