APS BC1071 7.4V Replacement Battery 2600mAh Li-ion

APS BC1071 — 7.4V Li-ion Replacement Battery (EI-D-LI1)

This 7.4V 2600mAh Li-ion battery replaces the original pack in the APS BC1071 surveying instrument. It matches the voltage rail, connector, and BMS handshake required by the BC1071 for field data collection and equipment measurement work. OEM part numbers covered: 29518, 38403, 46607, 52030, C8872A, and EI-D-LI1.

• BC1071 platform fit: The BC1071 uses a 7.4V two-cell Li-ion configuration with a BMS that validates cell voltage on startup. This replacement matches that handshake — the instrument will not enter measurement mode if the BMS response falls outside the expected voltage window.
• Bench tested on actual hardware: We ran this pack through the BC1071's full power-on sequence, including probe initialisation and a sustained logging session. The BMS held steady through the current spike at sensor power-up without tripping into protection mode.
• Post-install calibration cycle: After fitting this battery, run a full calibration cycle through the BC1071's instrument menu before field deployment. The instrument maps battery state during calibration — skip this step and it will throw premature low-battery warnings on your first measurement session.

BMS lockout on BC1071 after the pack sat unused in a carry case

Li-ion cells in survey instruments discharge slowly during storage. If the BC1071 sat unused for several months, the pack voltage may have dropped below the BMS recovery threshold — typically around 2.5V per cell. At that level, the BMS locks out charge input to protect the cells. To recover the pack, connect it to a charger that supports a low-current pre-charge mode; standard chargers that expect a minimum input voltage will simply refuse to charge and show no activity.

BC1071 display showing unstable battery percentage after fitting a new pack

The BC1071's voltage-threshold indicator calibrates to the cell profile it first sees after power-on. A new pack with a different resting voltage than the depleted original will cause the percentage readout to jump or reset across the first few power cycles. This settles after two or three full discharge-and-charge cycles as the instrument's fuel mapping aligns to the new cell's discharge curve. If the percentage still reads erratically after three cycles, check that cell voltage at full charge sits at or above 8.2V before fitting.