About this replacement
MODECOM MX3 — 3.7V Li-Polymer Replacement Battery (1ICP4/44/54)
This 3.7V, 1300mAh lithium-polymer cell replaces the original battery in the MODECOM MX3 portable GPS navigator. It connects via the 2PIN60 connector and fits the MX3's battery bay without modification. Capacity is 4.81Wh, matching the original specification.
- MX3 platform fit: The MX3 runs a low-voltage Li-Polymer power rail at 3.7V nominal. The 2PIN60 connector carries both the charge and discharge lines — no separate BMS communication wire is needed, so the swap is straightforward with no handshake requirement from the navigator's firmware.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the MX3 platform. The BMS held the charge cutoff cleanly at 4.2V and the low-voltage cutoff triggered at 3.0V without erratic shutdowns.
- Cold-start calibration after fitting: After fitting this cell, power the MX3 fully on outdoors and let it acquire a satellite fix before relying on it for navigation. GPS units perform a cold start after any full power interruption — first fix can take 5–10 minutes, while subsequent warm starts resolve in under a minute.
GPS accuracy reduced at low battery on the MX3
The MX3's GPS receiver draws consistent current during active navigation, but when battery voltage drops toward 3.2V, the unit begins reducing receiver sensitivity to protect the remaining charge. This shows up as position drift or a coarser fix — the device is still navigating, but the receiver is running at reduced power. A degraded original battery sits at a low state of charge far sooner than it appears to, so this symptom often precedes unexpected shutdowns. Fitting a fresh cell with full capacity restores the receiver to full sensitivity across the entire discharge curve.
MX3 shuts off without warning before the battery indicator reaches empty
The MX3's battery indicator is calibrated against the voltage curve of a new cell. As the original battery ages and its internal resistance rises, voltage sags faster under the load of active GPS and display operation — the device hits its hardware cutoff voltage while the indicator still shows one bar remaining. This is not a firmware fault; it is the BMS responding to an actual undervoltage condition. A replacement cell with low internal resistance restores the accuracy of that cutoff threshold. After fitting, allow a full charge to 4.2V before the first navigation session to let the indicator recalibrate against the new cell's curve.