Navcom PASSY 7.4V Li-ion Replacement Battery 2600mAh

Navcom PASSY / RT-3010S / SF-3040 / Ultra RTK — 7.4V Li-ion Replacement Battery

This 7.4V 2600mAh Li-ion battery replaces the original pack in the Navcom PASSY, RT-3010S, SF-3040, and Ultra RTK GNSS receivers. These are professional surveying instruments used for satellite-based positioning and field data collection. The cell pack measures 70.40 × 38.70 × 20.50mm and delivers 19.24Wh capacity.

• PASSY, RT-3010S, SF-3040, and Ultra RTK compatibility: All four models share the same 7.4V battery bay geometry and voltage rail requirements. The connector pinout and BMS communication protocol are consistent across this instrument family, so one pack covers the full group.
• Bench tested on actual hardware: We ran this pack through full charge cycles and monitored BMS handshake behaviour during satellite acquisition and active logging. The BMS held stable through the current spike that occurs when the GNSS module initialises on power-up.
• Post-install calibration cycle: After fitting this battery, run a full calibration cycle from the instrument's system menu before going into the field. The receiver maps battery state during calibration. Skipping this step causes the low-battery warning to fire early during your first measurement session, even with a full charge.

BMS lockout after the PASSY sat unused in a carry case for months

Li-ion cells self-discharge over storage. If the pack drops below approximately 2.5V per cell — around 5.0V total — the BMS enters a protection state and will not respond to a normal charge cycle. The charger sees no load and stops immediately. To recover, apply a low-current trickle charge at 0.1C using a compatible Li-ion charger until the pack rises above 6.0V, then continue with a standard charge cycle.

Receiver shuts down mid-logging session with no low-battery warning

This happens when sustained GNSS processing load pulls enough current to drag cell voltage below the BMS cutoff threshold — even if the display showed a healthy charge percentage moments before. The state-of-charge indicator on these receivers reads a voltage snapshot at startup, not a continuous measurement, so it can misrepresent available capacity under load. Charge the pack fully, then run the calibration cycle through the system menu before the next session. This recalibrates the threshold the instrument uses to trigger the warning.