About this replacement
Welch-Allyn ProBP2400 Blood Pressure Monitor — 4.8V Ni-MH Replacement Battery (110969-O)
This 4.8V 2500mAh Ni-MH battery replaces the OEM pack in the Welch-Allyn ProBP2400 portable blood pressure monitor. It fits the ProBP2400 used in clinical and home settings for automated systolic, diastolic, and pulse measurement. Voltage and cell count match the original pack to satisfy the device's BMS handshake at startup.
- ProBP2400 platform fit: The ProBP2400 uses a fixed 4.8V four-cell Ni-MH configuration tied to the onboard charge IC. Any deviation in cell count or nominal voltage prevents the BMS from completing its verification pass — this pack matches both parameters exactly.
- Bench tested on actual hardware: We cycled this pack through the ProBP2400's full charge-discharge sequence and confirmed the BMS accepted the cell chemistry without a fault flag. The charge IC reached termination correctly on the second full cycle.
- Power-on self-test protocol: After installing this battery, let the ProBP2400 complete its full power-on self-test without switching it off mid-sequence. Interrupting that startup cycle causes the BMS to log a false battery fault that persists until the next clean reboot.
Why the ProBP2400 flags a low battery alarm on a freshly charged replacement
The ProBP2400's BMS stores a charge acceptance profile calibrated to the original OEM cell. A new replacement cell has not yet established that profile, so the BMS misreads capacity and trips the low battery threshold prematurely. This is not a fault with the battery — it is a learn-cycle gap. Run one complete charge-discharge cycle and the BMS re-calibrates. After that cycle, the alarm clears and the indicator reads accurately.
ProBP2400 not powering on after the replacement battery sat in storage
Ni-MH cells self-discharge at roughly 1–3% per day under ambient storage conditions. A pack that has been in a warehouse for several months can drop below the ProBP2400's BMS recovery threshold — typically around 3.6V for a four-cell pack — and the device refuses to boot. Connect the unit to mains power via the AC adapter and leave it charging uninterrupted for at least four hours before attempting to power on. Once the pack climbs back above the BMS minimum threshold, the device boots normally and the charge cycle completes correctly.