Masimo Rainbow 14282 Replacement Battery 4.8V 2000mAh

Masimo Rainbow / Radical-7 — 4.8V Ni-MH Replacement Battery (14282)

This is a 4.8V, 2000mAh Ni-MH replacement battery for the Masimo Rainbow and Radical-7 pulse oximeters. It cross-references OEM part numbers 14282, B11588, and AMED3404. The Rainbow platform measures blood oxygen saturation and pulse rate non-invasively, and this battery keeps that monitoring capability portable and uninterrupted.

• Rainbow and Radical-7 compatibility: Both the Rainbow and Radical-7 share the same 4.8V battery bay, connector pinout, and BMS handshake protocol. A single cell pack covers the full platform without modification.
• Bench tested on actual hardware: We ran this battery through charge and discharge cycles on the Radical-7. The BMS accepted the cell, completed its initialisation sequence, and voltage held stable across the load profile typical of continuous SpO2 monitoring.
• Post-install self-test handling: After installing this battery, let the device complete its full power-on self-test without interrupting it. The Masimo BMS runs a battery verification step at startup — cutting power during this window registers a false battery fault that persists until the next clean reboot cycle.

Device not completing boot sequence after battery swap

The Radical-7 runs a multi-stage power-on self-test that includes a BMS verification pass. A fresh Ni-MH cell that hasn't completed its first full charge-discharge cycle may sit just below the voltage threshold the device expects at startup. The BMS reads the resting voltage of the new cell and can flag it as insufficient even when the cell is fully charged. Run one complete charge cycle before the first clinical use — the cell needs to reach its stable open-circuit voltage of approximately 5.4V at rest before the device accepts it cleanly.

Charge indicator not reaching 100% on first charge

On the first charge, the Radical-7's charge IC applies a conservative current limit to a new Ni-MH cell it hasn't profiled yet. The indicator may stall between 85–95% and appear stuck. This is the charge controller holding back until the cell's internal resistance stabilises — it is not a fault. Leave the device on charge until the indicator clears. After the first full cycle, subsequent charges reach 100% at normal speed.