Edan IM3 Patient Monitor Replacement Battery 11.1V 3400mAh

Edan IM3 / IM20 Series — 11.1V Li-ion Replacement Battery (21.21.064213-11)

This is an 11.1V 3400mAh Li-ion battery for the Edan IM3, IM12, IM20, and iM20 Transport Patient Monitor series. It replaces OEM part numbers 21.21.064213-11 and TWSLB-012. These monitors are portable clinical vital signs units — ECG, SpO2, NIBP, temperature — and this battery is what keeps them running away from wall power.

• IM3 / IM12 / IM20 platform compatibility: These models share a common battery bay, connector pinout, and BMS handshake protocol across the series. The same 11.1V three-cell Li-ion configuration satisfies the charge IC and power management firmware across all listed variants.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on IM-series hardware. The BMS accepted the new cell without fault flags, the charge IC ramped correctly through CC/CV stages, and the protection circuit responded accurately to load transitions during the monitor's active display and alarm cycles.
• Post-installation self-test cycle: After fitting this battery, let the monitor complete its full power-on self-test without interruption. The IM series runs a BMS verification sequence at boot — cutting power mid-sequence writes a battery fault to the device log that persists until the next clean reboot.

IM3 alarming low battery immediately after a confirmed full charge

The IM3's charge IC calibrates its capacity estimate against the OEM cell's known chemistry profile. A new replacement cell hasn't yet built a discharge history the BMS can reference, so the state-of-charge algorithm reads conservatively and triggers the low-battery threshold early. This is not a defective cell. Run one complete charge-to-discharge-to-full-recharge cycle under normal monitor load before trusting the battery indicator. After that conditioning cycle, the BMS recalibrates and the alarm threshold maps correctly to actual cell capacity.

Monitor will not power on after the replacement battery was stored before installation

Li-ion cells self-discharge during storage at roughly 2–3% per month. If the cell dropped below the IM series BMS recovery threshold — typically around 9V for an 11.1V three-cell pack — the protection circuit latches off and blocks output entirely. Connect the monitor to mains power first, not the battery alone. The charger circuit can push a pre-charge recovery current into a latched pack that the device's own power rail cannot. Leave it on mains for at least 30 minutes before attempting to boot on battery power.