Mitac Mio 138 GPS Compatible Battery 3.7V 1250mAh

Mitac Mio 138 / Mio 268 Series — 3.7V Li-ion Replacement Battery

This is a 3.7V 1250mAh Li-ion cell for the Mitac Mio 138, Mio 268, Mio 268 Plus, Mio 269, and six additional models in the same navigator family. It replaces the original internal battery in these portable GPS units. Swap it when the existing cell no longer holds charge through a typical navigation session.

• Mio 138 / 268 series compatibility: All listed models share the same 3.7V single-cell architecture, physical footprint (49.56 × 36.12 × 6.46mm), and connector orientation. The BMS accepts the same charge profile, so a single cell covers the entire group without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on GPS-class hardware and confirmed the BMS completed charge termination cleanly at full voltage with no false-peak cutoff or thermal event at ambient temperature.
• Cold-start satellite acquisition after fitting: After fitting this cell, power the unit on outdoors before your first drive and allow it to acquire a satellite fix while stationary. A full power interruption triggers a cold start — first fix typically takes 5–10 minutes. Subsequent warm starts run under a minute once the almanac is cached.

GPS accuracy reduced when battery charge drops below 20%

Several Mio-series units reduce GPS receiver sensitivity as a power-saving measure when cell voltage falls toward the low-threshold cutoff. The receiver draws fewer active channels, which narrows the satellite count and can degrade position accuracy by tens of metres. This is firmware behaviour, not a fault with the cell. Keeping the battery above 20% charge during active navigation prevents the device from entering that reduced-power receiver state.

Mio shuts off without warning before the battery indicator hits empty

The on-screen battery gauge in these navigators is calibrated to the original cell's discharge curve. A new cell — or a worn one with shifted internal resistance — hits the hardware voltage cutoff before the indicator reaches zero bars. The unit powers off abruptly because the voltage floor is crossed while the gauge still shows remaining charge. To recalibrate, run two full discharge-to-shutoff and full-recharge cycles, then check whether the indicator tracks more accurately against actual runtime.