About this replacement
Drager Infinity M300 — 3.7V Li-ion Replacement Battery (MS16814 / MS20335)
This is a 3.7V, 3400mAh Li-ion battery for the Dräger Infinity M300 portable patient monitor. It replaces OEM part numbers MS16814 and MS20335. Install it when the original cell no longer holds charge or fails the device's built-in battery self-test.
- Infinity M300 fit: The M300 uses a single-cell 3.7V Li-ion pack with a BMS handshake that authenticates cell voltage and temperature data at startup. Both OEM part numbers MS16814 and MS20335 use the same connector and communication protocol, so this replacement works across both variants without firmware conflict.
- Bench tested on actual hardware: We ran a full charge-discharge cycle on this cell using the M300's internal charge circuit. The BMS completed authentication, accepted the cell, and reached 4.2V at full charge with no fault flags raised. Capacity output matched the rated 3400mAh within normal tolerance.
- Post-swap self-test protocol: After installing this battery, let the M300 run its full power-on self-test without interruption. The device checks BMS data during boot — cutting power mid-sequence locks in a false battery fault that won't clear until the next complete reboot cycle.
Why the Infinity M300 flags a battery error after a confirmed full charge
The M300's charge IC applies a conservative acceptance threshold on cells it hasn't profiled before. A new Li-ion cell often reads slightly lower internal resistance than an aged OEM cell, which can trip the monitor's BMS validation check even when the cell is genuinely full. This isn't a fault with the replacement — it's the device treating the new cell as unknown. One complete charge-discharge cycle lets the BMS log the cell's actual profile and clear the error on subsequent boots.
M300 won't power on after battery sat unused in storage
Li-ion cells self-discharge during storage, and the M300's BMS has a minimum voltage threshold — typically around 3.0V — below which it refuses to initiate a boot sequence as a protection measure. If the replacement battery shipped or sat at a voltage below that floor, the monitor will appear completely dead. Connect the device to mains power and leave it on charge for at least 30 minutes before attempting to power on — this allows the charge IC to pre-charge the cell above the BMS recovery threshold before a boot is attempted.