Tianbao 92600 Replacement Battery 7.4V 3400mAh Li-ion

Tianbao 92600 / MA1805A — 7.4V Li-ion Replacement Battery

This is a 7.4V, 3400mAh (25.16Wh) Li-ion replacement battery for Tianbao professional survey and field measurement instruments. It fits equipment referencing OEM part numbers 92600, 92670, and MA1805A. If your original pack no longer holds charge or fails to power the instrument through a full measurement session, this is the direct swap.

• 92600 / 92670 / MA1805A compatibility: These three part numbers reference the same 7.4V Li-ion platform used across Tianbao field instruments. The cell count, connector pinout, and BMS communication protocol are identical across the group — one replacement covers all three.
• Bench tested on actual hardware: We cycled this pack through probe initialisation sequences and sustained sensor logging loads. The BMS handled the current spike at probe power-up without tripping, and voltage held steady under continuous measurement draw.
• First-deployment calibration step: After installing this pack, run a full calibration cycle through the instrument menu before heading into the field. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings to appear during your first measurement session even when the pack is fully charged.

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

Li-ion cells self-discharge slowly in storage. If the pack drops below approximately 2.5V per cell during extended storage, the BMS enters a protective lockout state and blocks charge input. The instrument will show no response — no charging indicator, no power-on. Connect the pack to the charger for at least 15–20 minutes before concluding it is dead; many chargers apply a low-current trickle to recover cells from this state. Once the pack reaches around 3.0V per cell, normal charging resumes.

Voltage dropout causing readings to reset or drift mid-logging session

Sustained sensor loads draw more current than brief power-on cycles, and an aged or marginal cell will sag in voltage under that load even if the charge indicator looked healthy at startup. When cell voltage dips below the instrument's operating threshold mid-session, the processor resets or the measurement module loses power momentarily — logged data can corrupt or readings reset to zero. A new pack with full cell capacity maintains voltage above the dropout threshold under continuous load. Confirm cell voltage is above 7.0V under load using a multimeter before deploying on a long field session.