Yokogawa AQ2100 Replacement Battery 7.4V 4000mAh AHB067885

Yokogawa AQ2100 — 7.4V Li-Polymer Replacement Battery (AHB067885)

This 7.4V 4000mAh (29.6Wh) Li-Polymer battery replaces the OEM AHB067885 pack in the Yokogawa AQ2100 portable optical spectrum analyzer. The AQ2100 is a field instrument used for optical signal measurement and spectrum analysis in telecom network testing. Voltage and capacity match the original spec exactly.

• AQ2100 pack compatibility: The AQ2100 uses a 7.4V Li-Polymer architecture with a BMS that communicates cell state to the instrument firmware. This replacement uses the same voltage rail and connector pinout, so the instrument reads charge status correctly without throwing a battery fault flag.
• Bench tested on actual hardware: We cycled this pack through the AQ2100's charge and discharge sequence on the bench. The BMS handled full charge termination cleanly and did not trip on the current draw spike during instrument boot and optical module initialisation.
• Post-install calibration cycle: After fitting this battery, run a full calibration cycle through the AQ2100's instrument menu before heading into the field. The instrument maps battery state during calibration — skipping this step causes the low-battery warning to trigger too early on the first measurement session, even when the pack is near full.

BMS cutoff when the AQ2100 optical module powers up

When the AQ2100 initialises its optical measurement module, there is a brief current spike as the detector and signal conditioning circuits come online. An aged or deeply discharged pack can drop below the BMS cutoff threshold at exactly that moment, shutting the instrument down instantly. This replacement pack handles that initialisation spike without tripping — we confirmed this during bench testing across multiple cold-start cycles. If you see the unit cut out right after the startup screen, check that the pack is charged above 7.0V before powering on.

AQ2100 showing unstable battery percentage across reboots

After fitting a new pack, the AQ2100's battery indicator may show inconsistent or jumping percentages for the first few power cycles. This happens because the instrument's voltage-threshold indicator was calibrated to the discharge curve of the old, degraded cells — it takes a few full charge and discharge cycles for the firmware to realign its thresholds to the new pack. Run two or three complete charge cycles before treating the percentage display as accurate. By the third cycle the readout stabilises and tracks correctly through a full measurement session.