Magellan RoadMate RV 9490T-LMB Compatible Battery 3.7V 1100mAh

Magellan RoadMate RV 9490T-LMB — 3.7V Li-ion Replacement Battery (BP-N399-11/1100)

This 3.7V 1100mAh Li-ion cell replaces the original battery in the Magellan RoadMate RV 9490T-LMB portable GPS navigator. It matches the OEM part number BP-N399-11/1100 and fits the physical cavity and connector on this unit. Capacity is 4.07Wh — identical to the factory specification.

• RoadMate RV 9490T-LMB fit: The 9490T-LMB uses a compact single-cell 3.7V pack with a low-current BMS suited to the GPS receiver and display load. The connector orientation and PCB tab spacing on this replacement match the OEM pack — no modification needed to seat it.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the 9490T-LMB platform. The BMS accepted charge from the unit's internal charging circuit without error flags, and the GPS powered through satellite acquisition without voltage sag tripping a cutoff.
• Cold-start initialisation after fitting: After any full power removal, the 9490T-LMB performs a GPS cold start. Take the unit outdoors and power it on before driving — allow 5 to 10 minutes for first satellite fix. Subsequent warm starts lock in under a minute once the almanac is cached.

GPS accuracy reduced when battery drops below 3.5V

At low charge states, the 9490T-LMB scales back receiver sensitivity to reduce current draw from the cell. This shows up as slower re-acquisition in urban canyons or tunnels, and position drift on the map. The GPS is not faulty — it is throttling the RF front end to stay within what the weakened cell can supply. Keep the unit charged above 3.6V during active navigation to hold full receiver performance.

Unit shuts off without a low-battery warning on the screen

The battery indicator on the 9490T-LMB is calibrated to the original cell's discharge curve. After a swap, the firmware has not re-learned the new cell's actual capacity, so the voltage threshold for shutdown can be hit before the on-screen indicator reaches the red zone. Charge the replacement cell fully and run two complete discharge cycles through normal use — the indicator recalibrates itself and warning timing returns to normal. If shutdown is still occurring at 3.6V or above, check the connector pins for seating.