About this replacement
Puritan Bennett Renaissance II — 4.8V Ni-MH Replacement Battery (P-495219-00)
This 4.8V, 1800mAh Ni-MH battery replaces the OEM pack in the Puritan Bennett Renaissance II portable oxygen concentrator. It fits the Renaissance II, model 49221900, and PB700 platforms. Voltage and capacity match the original specification — the concentrator's compressor and oxygen generation system draw exactly what this cell is rated to supply.
- Renaissance II / PB700 platform compatibility: These models share the same 4.8V battery bay, connector pinout, and BMS handshake protocol. One cell pack covers all three listed variants without modification.
- Bench tested on actual hardware: We cycled this pack through the Renaissance II's full charge-discharge profile. The BMS accepted the cell on first insertion, completed its verification handshake, and held charge without triggering a fault code across multiple load cycles.
- Post-swap self-test protocol: After installing this battery, let the Renaissance II complete its full power-on self-test without interruption. The device runs a BMS verification sequence at startup — cutting power during this window writes a false battery fault to memory that persists until a complete reboot and clean restart.
Why the Renaissance II alarms low battery with a freshly charged replacement installed
The Renaissance II BMS calibrates its charge threshold against the OEM cell's established charge curve. A new Ni-MH cell hasn't built that history yet — its internal resistance reads slightly higher on the first few cycles, which the BMS interprets as a low-capacity pack. This is a learn-cycle artefact, not a fault with the replacement cell. Run one complete charge-discharge cycle and the BMS recalibrates its baseline. The alarm clears on its own once the cell passes the internal threshold check, typically after that first full cycle.
Renaissance II won't power on after the replacement cell sat in storage
Ni-MH cells self-discharge over time, and a pack that's been sitting in storage may drop below the Renaissance II's BMS recovery threshold — typically around 4.0V for a 4.8V pack. Below that voltage, the BMS treats the cell as damaged and blocks startup to protect the concentrator's electronics. Place the pack on charge for a full uninterrupted cycle before attempting to power on the device. If the charger indicates a fault rather than charging, check the pack voltage with a multimeter — a reading above 3.8V means the BMS can still recover the cell with a slow charge.