Masimo 23893 Radical-7 Replacement Battery 11.1V 5200mAh

Masimo Radical-7 / Root Platform — 11.1V Li-ion Replacement Battery (P1239900132)

This 11.1V, 5200mAh Li-ion battery fits the Masimo Radical-7 Pulse CO-Oximeter (model 23893), the RDS7, and the Root Monitoring Platform. It replaces OEM part numbers P1239900132, P1741000086, and 23893. Voltage and cell chemistry match the original battery bay spec exactly.

• Radical-7, RDS7, and Root platform compatibility: All three platforms share the same 11.1V three-cell Li-ion architecture and battery connector pinout. The BMS handshake protocol is identical across this family, so one cell configuration covers the full group without hardware modification.
• Bench tested on actual hardware: We cycled this battery through charge and discharge on a clinical monitor bench rig. The BMS accepted the cell pack on first connection, completed the self-test sequence without fault flags, and held voltage within spec across the full discharge curve.
• Power-on self-test protocol: After installing this battery, let the Radical-7 complete its full boot and BMS verification cycle without interruption. Cutting power during that startup sequence causes the device to log a false battery fault that persists until the next clean reboot from a full charge.

Why the Radical-7 alarms low battery immediately after a confirmed full charge

The Radical-7 BMS stores a learned capacity profile from the previous cell. A new cell has no charge history, so the BMS applies its most conservative threshold and flags a low-battery alarm even when the pack is fully charged. This is not a fault with the replacement cell — it is the BMS running without a baseline. Run one complete charge-to-discharge-to-charge cycle and the BMS updates its profile. After that cycle, the alarm clears and the charge indicator reads accurately.

Device will not power on after the battery sat in storage

Li-ion cells self-discharge during storage. If this battery spent extended time in a warehouse, cell voltage may have dropped below the Radical-7's BMS recovery threshold — typically around 9V for an 11.1V three-cell pack. The monitor will not attempt a boot below that threshold as a safety measure. Connect the battery to the OEM charger and leave it for at least 60 minutes before pressing the power button. Most cells recover to the boot threshold within that window and the device powers on normally.