i.Trek M5 GPS Replacement Battery 3.7V 1050mAh Li-ion

i.Trek M5 / M5 BT GPS — 3.7V Li-ion Replacement Battery

This 3.7V 1050mAh Li-ion cell is a direct replacement for the i.Trek M5 and M5 BT portable GPS navigator. It fits both the standard M5 and the Bluetooth-enabled M5 BT variant, which share the same battery bay and connector. Dimensions are 52.99 × 35.51 × 7.16mm — measure your original before fitting if you are unsure.

• M5 and M5 BT compatibility: Both models use the same 3.7V cell, battery bay footprint, and connector pinout. The BT variant adds Bluetooth circuitry but draws from the same power rail, so one cell covers both.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a GPS navigator load profile. The protection circuit handled low-voltage cutoff cleanly and did not trip on normal GPS receiver draw.
• Cold-start behaviour after fitting: After fitting this cell, power the unit on outdoors and let it acquire a satellite fix before relying on it. A full power interruption clears the GPS receiver's ephemeris data, so first fix can take 5–10 minutes. Subsequent locks are under a minute once the almanac rebuilds.

GPS accuracy reduced as battery level drops on the M5

Some GPS receivers scale back RF front-end sensitivity at low battery voltage to stay within power budget. On the M5, this can show up as position drift or a weaker satellite signal count before the low-battery indicator even triggers. The fix is straightforward: keep the cell above the threshold where the receiver throttles down. A fresh, correctly rated cell at 3.7V nominal holds the receiver in full-sensitivity mode for the working portion of the discharge curve.

M5 shuts off without warning instead of showing a low-battery alert

This happens when the fuel gauge or voltage threshold that drives the on-screen indicator is no longer calibrated to the actual cell. A worn or mismatched cell can sag below the cutoff voltage under GPS receiver load before the visual warning fires. The device then shuts down with no apparent warning. After fitting a new cell, run one full charge-to-cutoff cycle so the unit can re-anchor its voltage-to-capacity mapping. The on-screen indicator should align with actual remaining charge once the cell reaches a resting voltage of approximately 3.7V at midpoint.