Haicom 406-C Compatible Battery BA-01 3.7V 1000mAh

Haicom 406-C — 3.7V Li-ion Replacement Battery (BA-01)

This 3.7V 1000mAh Li-ion cell replaces the original BA-01 battery in the Haicom 406-C portable GPS navigator. It restores power to the GPS receiver, display, and onboard memory functions. Capacity is 1000mAh (3.7Wh), matching the stock specification.

• 406-C battery platform: The 406-C uses a single-cell Li-ion pack at 3.7V nominal with a built-in BMS that manages charge cutoff and low-voltage protection. The BA-01 form factor is specific to this unit — the 52.96 x 33.64 x 5.15mm cell dimensions leave no margin for substitution with a generic cell.
• Bench tested on actual hardware: We ran the cell through charge and discharge cycles and confirmed BMS cutoff fired correctly at the low-voltage threshold. The charge circuit accepted the cell without fault flags.
• Post-swap first fix: After fitting this cell, power the unit on outdoors and let it run until it acquires a satellite fix before using navigation. Full power removal triggers a cold start — the receiver takes 5–10 minutes to pull fresh almanac data versus under a minute on a warm restart. Do not interrupt this first fix cycle.

GPS accuracy reduced when battery drops below 3.5V

Some portable GPS units reduce RF receiver sensitivity as a power-saving measure once cell voltage drops under a threshold — typically around 3.5V on a 3.7V nominal cell. On the 406-C, this can show up as a weaker satellite signal bar count and occasional position jumps before the low-battery icon appears. The display circuit draws less current than the GPS receiver, so the unit can still look functional on screen while the receiver is already underperforming. Charge the unit before voltage drops below 3.5V to keep the receiver running at full sensitivity.

Saved routes or POIs missing after battery swap

The 406-C holds some user data — saved routes, favourites, and POIs — in RAM that relies on continuous battery voltage to retain its state. A full power removal, like a battery swap, clears this volatile memory. Flash-stored map data survives because it does not need continuous power, but anything written to RAM since the last sync does not. Before removing the old cell, export saved routes to a PC via the device's data transfer function so you can reload them after the swap.