Drager MSI PG4000 Replacement Battery 3.7V 2200mAh

Drager MSI PG4000 / FG4200 — 3.7V Li-Polymer Replacement Battery (504053 / 2450-3004)

This 3.7V 2200mAh Li-Polymer pack replaces the original battery in the Drager MSI PG4000 and MSI FG4200 portable multi-gas detectors. Both instruments use the same cell format, connector, and BMS handshake, so one part number covers both. Capacity is 2200mAh (8.14Wh), matching OEM spec.

• PG4000 and FG4200 shared platform: Both detectors run on the same 3.7V Li-Polymer cell with identical connector pinout and BMS communication protocol. A single replacement pack services either unit without modification.
• Bench tested on actual hardware: We cycled this pack through sensor-initialisation sequences on the PG4000. The BMS held stable through the current spike at electrochemical sensor power-up and maintained charge delivery through sustained four-gas monitoring loads.
• Post-install calibration requirement: After fitting this pack, run a full calibration cycle through the instrument menu before field deployment. The PG4000 maps battery state during calibration — skipping this step causes premature low-battery warnings to appear during the first gas survey session.

BMS lockout after the PG4000 sat unused in a carry case for months

Li-Polymer cells in standby instruments self-discharge slowly. If cell voltage drops below approximately 2.5V, the battery's protection circuit locks out to prevent damage to the cells. The PG4000 will not power on and the charger shows no activity. To recover, connect the instrument to its charger and leave it for at least 30–60 minutes — most chargers trickle current into a locked-out pack at a low rate until cell voltage climbs back above the 2.8V recovery threshold, at which point normal charging resumes.

Readings drifting or resetting mid-session during continuous gas logging

Under sustained sensor load — particularly with four gas channels active and the pump running simultaneously — the cell voltage can sag enough to momentarily drop below the instrument's operating floor. The PG4000 interprets this as a low-voltage event and resets the active logging session. This is not a faulty pack; it indicates the original battery's internal resistance has risen too high to sustain the combined draw. Fitting a fresh pack with lower internal resistance restores stable voltage delivery — confirm cell voltage holds above 3.5V under full sensor load during your first post-install calibration.