About this replacement
Edan iM3s Monitor — 3.7V Li-Polymer Replacement Battery (01.21.064397)
This 3.7V, 2000mAh lithium-polymer battery replaces the internal cell in the Edan iM3s patient monitor. The iM3s is a portable clinical vital signs monitor used in hospital wards and point-of-care settings. It tracks heart rate, SpO₂, blood pressure, and other patient parameters — so power continuity matters.
- iM3s platform fit: The iM3s uses a single-cell Li-Polymer pack at 3.7V nominal. The BMS on this monitor negotiates with the cell over a dedicated communication line. Voltage rail, connector pinout, and pack dimensions (49 × 47 × 12mm) all match the OEM specification.
- Bench tested on actual hardware: We cycled this cell through the iM3s charge IC and confirmed the BMS handshake completes without a fault flag. Charge termination behaved correctly, and the monitor accepted the cell without throwing a battery-type error.
- Post-swap startup protocol: After fitting this battery, allow the iM3s to complete its full power-on self-test without interruption. The monitor runs a BMS verification sequence at boot. Cutting power during that sequence locks in a false battery fault that persists until the next clean reboot.
Why the iM3s charges slowly or stops short of 100% on the first cycle
The iM3s charge IC applies a conservative current limit when it first encounters a new cell. It treats an unknown capacity state as a safety condition and throttles the charge rate until internal resistance data is logged. This is normal behaviour on the first charge, not a fault. Run one complete charge-to-full cycle and the IC recalibrates — subsequent charges reach 100% at normal speed.
iM3s showing low-battery alarm immediately after a confirmed full charge
The BMS compares cell voltage against a threshold calibrated for the OEM cell chemistry. A new replacement cell that hasn't completed a full charge-discharge cycle may read slightly below that threshold at rest, triggering the alarm even at full charge. This is a BMS learn-cycle issue, not a defective cell. Run one complete charge-discharge cycle on the iM3s before clinical use — the BMS recalibrates its cutoff reference and the alarm clears. Do not place the device in clinical service until that cycle is complete and the alarm does not recur.