RAE Systems MultiRAE Plus 4.8V Replacement Battery 500-0037-100

RAE Systems MultiRAE Plus / PGM-50 — 4.8V Ni-MH Replacement Battery (500-0037-100)

This is a 4.8V 2000mAh Ni-MH replacement battery for the RAE Systems MultiRAE Plus, MultiRAE Qrae, and PGM-50 portable multi-gas detectors. It replaces OEM parts 500-0037-100, CD500-0059-000-FRU, and 0059 0039 0037. The pack slots into the same battery compartment and connects to the same BMS handshake the instrument expects at power-up.

• MultiRAE Plus, Qrae, and PGM-50 compatibility: These three instruments share the same 4.8V four-cell NiMH pack format, connector pinout, and BMS communication protocol. A single battery revision covers all three because RAE Systems standardised the power rail across this detector family.
• Bench tested on actual hardware: We ran this pack through the PGM-50 power-up sequence and monitored the BMS handshake during sensor initialisation. The pack held voltage above the cutoff threshold during the electrochemical sensor warm-up draw and passed the instrument's internal battery check without fault codes.
• First-use calibration cycle: After installing this pack, run a full calibration cycle through the instrument menu before field deployment. The MultiRAE maps battery state during calibration — skipping this step causes premature low-battery warnings to appear during the first measurement session, even on a fully charged pack.

PGM-50 and MultiRAE Plus shutting down mid-survey with no warning

This happens when the electrochemical sensor array draws a combined initialisation current that pushes the pack voltage below the BMS cutoff threshold — typically around 4.2V under load for a four-cell NiMH string. An aged original pack with degraded cells hits this threshold during the sensor polling cycle, not during idle. The instrument interprets the voltage drop as a dead battery and cuts power immediately. Replacing the pack and running a calibration cycle before the next field session resets the instrument's voltage-state map and stops the unexpected shutdowns.

MultiRAE Qrae not recognising the new pack after long storage

If the instrument sat unused for several months with the original pack still installed, the cells may have self-discharged below the BMS recovery threshold — often under 4.0V for this pack format. The BMS enters a sleep state and the instrument either shows a battery error or fails to power on at all. Place the pack on the charger for a minimum 30-minute pre-charge pass before inserting it into the instrument. If the charger does not begin the charge cycle, hold it at a trickle input using a compatible NiMH charger set to 100mA until the pack recovers to 4.4V, then switch to normal charge.