RAE Systems QRAE II Replacement Battery 3.7V 2300mAh

RAE Systems QRAE II Gas Monitor — 3.7V Li-Polymer Replacement Battery (20-3402-000)

This 3.7V, 2300mAh lithium-polymer battery replaces the OEM pack in the RAE Systems QRAE II portable multi-gas detector. It fits the QRAE II and QRAE II Gas Monitor Detector used in confined space entry, industrial hygiene surveys, and hazardous area inspections. Voltage and capacity match the original specification exactly.

• QRAE II platform fit: The QRAE II uses a single-cell Li-Polymer pack with a proprietary connector and onboard BMS handshake. This replacement carries the same cell geometry — 56.90 × 47.62 × 17.24mm — and communicates correctly with the instrument's power management circuit so the detector boots normally and displays charge state without fault codes.
• Bench tested on actual hardware: We ran this pack through the QRAE II power-up sequence and sustained sensor load across the electrochemical, LEL, and oxygen channels simultaneously. The BMS held voltage steady under the combined sensor draw and did not trip during gas-alarm events, which briefly spike current as the audible and visual alerts fire together.
• Post-install calibration cycle: After fitting this battery, run a full calibration cycle through the QRAE II instrument menu before field deployment. The detector maps battery state during calibration, and skipping this step causes premature low-battery warnings to appear on the first monitoring session even when the pack is fully charged.

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

Li-Polymer cells self-discharge slowly during storage. If the QRAE II was left in a bag for several months, the cell voltage may have dropped below the BMS recovery threshold — typically around 2.5V for single-cell packs. When this happens, the BMS latches into a protective lockout state and the charger sees no load, so the indicator light either stays off or flashes an error. Place the detector on charge for at least 30 minutes without interruption; most BMS circuits include a trickle-recovery mode that will slowly raise cell voltage back above the 2.7V reinitialisation threshold before allowing a normal charge cycle to begin.

Readings drifting or logging session resetting mid-survey

The QRAE II's electrochemical sensors draw sustained current throughout a logging session, and an aged or partially depleted pack can sag below the detector's minimum operating voltage under that load even when the charge indicator still shows bars. When voltage droops momentarily, the instrument's processor resets and the active log entry is lost. This is a voltage-dropout failure, not a firmware issue. Fitting a fresh pack and confirming the open-circuit voltage reads at or above 3.9V before deployment will prevent mid-session resets.