i.Trek NTA2236 M3 BT GPS Replacement Battery 3.7V 1800mAh

i.Trek M3 BT GPS — 3.7V Li-ion Replacement Battery (NTA2236)

This 3.7V 1800mAh Li-ion cell replaces the original battery in the i.Trek M3 BT GPS handheld navigator. It fits the compact M3 BT GPS unit used for hiking, geocaching, and travel navigation. Dimensions are 52.98 × 35.39 × 11.61mm — confirm against your existing cell before fitting.

• M3 BT GPS fit: The M3 BT GPS uses a single-cell Li-ion pack at 3.7V nominal. This cell matches that voltage rail and the original connector orientation, so the BMS handshake completes without fault flags on power-up.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the M3 BT GPS platform. The onboard BMS accepted the cell, charge termination triggered correctly at 4.2V, and low-voltage cutoff held at the expected threshold without premature shutdown.
• Cold-start satellite acquisition after swap: After fitting this cell, power the unit on outdoors in open sky and let it run until it acquires a satellite fix. The M3 BT GPS performs a cold start after any full power interruption — first fix can take 5–10 minutes versus under a minute on a warm start.

GPS accuracy reduced at low battery on the M3 BT GPS

As cell voltage drops toward the low-voltage cutoff threshold, some GPS receivers reduce RF front-end sensitivity to conserve current draw. On the M3 BT GPS this can widen position error before the low-battery indicator even triggers. You may notice the fix drifting or the unit struggling to hold lock in moderate tree cover. Keep the cell above 3.6V during active navigation to maintain full receiver sensitivity.

M3 BT GPS shuts off without warning before the battery indicator empties

A new cell has a slightly different discharge curve than a degraded original battery. The M3 BT GPS fuel gauge is calibrated against a worn cell's curve, so the visual indicator can read one or two bars remaining while actual voltage has already hit the BMS cutoff threshold. The device then shuts off abruptly with no final warning. Run two or three full charge-to-cutoff cycles to let the gauge re-calibrate against the new cell's curve.