TK7N6384 Fuji 7.4V Survey Instrument Compatible Battery 2600mAh

Fuji Electric Systems — 7.4V Li-ion Replacement Battery (TK7N6384)

This 7.4V, 2600mAh Li-ion battery replaces the OEM TK7N6384 pack used in Fuji Electric survey and test instruments. It fits portable measurement and diagnostic equipment used in professional fieldwork and inspection tasks. Voltage and capacity match the original spec exactly.

• Survey and test instrument fit: These instruments share a common 7.4V two-cell Li-ion architecture with a BMS handshake that monitors cell voltage balance and current draw. The connector and cell configuration match the TK7N6384 footprint, so the pack seats and communicates correctly with the instrument's power management circuit.
• Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on a 7.4V Li-ion test rig. The BMS responded correctly to charge termination, and cell balancing completed without error flags or protection trips under normal instrument load.
• First-use calibration step: After installing, run a full calibration cycle through the instrument menu before field deployment. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings on the first measurement session.

BMS cutoff when a probe or sensor module initialises

Survey instruments draw a short current spike the moment a probe or sensor module powers up. If the pack's BMS threshold is set conservatively, this spike can trip the protection circuit and cut power before a single reading is taken. This is more likely with an aged or deeply discharged pack where internal resistance has climbed. A fresh, fully charged pack at 8.4V handles the inrush without triggering cutoff.

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

Sustained sensor load during a logging session pulls more current than idle display use. If the pack's cells are unbalanced, one cell can sag below the BMS cutoff threshold while the other still reads normal — the instrument shuts off without a warning because average voltage looked fine until that moment. This happens most often with packs that have accumulated shallow charge cycles. Fully discharging and recharging once resets the cell balance and eliminates the mid-session dropout.