About this replacement
Puritan Bennett PB110 / Nellcor — 3.6V Ni-MH Replacement Battery (5677)
This 3.6V Ni-MH battery at 2000mAh (7.2Wh) replaces the original cell in the Puritan Bennett PB110, PB 100, and Nellcor pulse oximetry monitors. These devices display patient blood oxygen saturation and heart rate in clinical and home healthcare settings. OEM part numbers covered: 5677 and B10667.
- PB110, PB 100, and Nellcor platform fit: These three models share the same 3.6V single-cell Ni-MH power rail, connector pinout, and BMS handshake protocol — one battery services all three variants without modification.
- Bench tested on actual hardware: We cycled this cell through charge and load on the PB110 platform. The BMS completed its verification pass and the device held stable voltage under the monitor's intermittent SpO2 sampling load profile.
- Post-swap self-test protocol: After installing this cell, allow the monitor to complete its full power-on self-test without interruption. Nellcor devices run a BMS verification sequence at startup — cutting power mid-cycle logs a false battery fault that persists until the next clean reboot.
Why the PB110 alarms low battery immediately after a confirmed full charge
The Nellcor BMS stores a chemistry baseline from the original factory cell. A new Ni-MH replacement presents a slightly different internal resistance profile, and the BMS flags this as a low-state cell on first boot. This is not a defect in the battery. Run one full charge-to-discharge cycle and the BMS recalibrates its threshold to match the new cell's actual capacity curve. After that first conditioning cycle, the low-battery alarm clears and does not return at full charge.
Monitor will not power on after the replacement cell sat in storage
Ni-MH cells self-discharge at roughly 1–2% per day in storage. If this battery shipped or sat unused for several weeks, its resting voltage may have dropped below the BMS recovery threshold — typically around 3.0V for a 3.6V nominal cell. The BMS interprets anything below that floor as a damaged or missing cell and blocks startup. Place the battery on charge for a full uninterrupted cycle before attempting to power on the monitor. Once voltage climbs back above the 3.0V threshold, the BMS releases the block and the device boots normally.