Bionet BM3 Patient Monitor Replacement Battery 11.1V 2600mAh

Bionet BM3 / BM5 Series — 11.1V Li-ion Replacement Battery (BM-BAT-4)

This 11.1V, 2600mAh (28.86Wh) Li-ion battery replaces the original power cell in the Bionet BM3, BM3 Plus, and BM5 patient monitors. These are bedside vital signs monitors used in clinical environments to track SpO2, NIBP, heart rate, and temperature. The OEM part numbers covered are LS1865L220 3SIPMXZ and BM-BAT-4.

• BM3, BM3 Plus, and BM5 compatibility: All three models share the same 11.1V battery bay, connector pinout, and BMS communication protocol. The charge IC in each device reads cell chemistry data at startup — this battery matches the expected Li-ion profile so the handshake completes without triggering a battery fault.
• Bench tested on actual hardware: We ran this cell through the BM3 power-on self-test sequence and confirmed the BMS completed its verification pass. The charge cycle accepted current normally and the device reported battery status without error flags on the display.
• Startup sequence after installation: After fitting this battery, allow the BM3 to complete its full power-on self-test without interruption. Medical device BMS verification runs at boot — cutting power mid-sequence creates a false battery fault that persists until the next clean reboot cycle.

BM3 alarming low battery immediately after a confirmed full charge

The BM3's charge IC applies a conservative capacity threshold when it first reads a new cell. On the initial charge, the BMS has not yet completed a learn cycle, so it compares the new cell's state-of-charge data against a stored OEM baseline — if the profile doesn't match exactly, the device flags low battery even at full charge. Running one complete charge-to-discharge-to-full-charge cycle teaches the BMS the actual cell behaviour. After that first cycle, the alarm clears and the charge indicator reads accurately. Do not place the device in clinical use until this calibration cycle is finished.

BM3 will not power on after the replacement battery sat in storage

Li-ion cells self-discharge during storage. If the cell voltage has dropped below approximately 9V — the BMS deep-discharge cutoff threshold for an 11.1V three-cell pack — the device protection circuit blocks output entirely and the monitor will not respond to the power button. Connect the battery to the device and leave it on charge for at least 30 minutes before attempting to power on. The charge IC in the BM3 applies a low-rate pre-charge current to recover cells below cutoff before switching to full charge rate. If the charge LED does not illuminate within five minutes of connection, check the dock contacts and retry.