About this replacement
Onyx Healthcare OPM-P02T Series — 10.9V Li-ion Replacement Battery (9789BALX02)
This is a 10.9V, 8400mAh Li-ion replacement battery for the Onyx Healthcare OPM-P02T and OPM-P02T-00 pulse oximeters. These portable patient monitoring devices measure blood oxygen saturation and heart rate in clinical and home care settings. OEM part number 9789BALX02 cross-references directly to this cell pack.
- OPM-P02T and OPM-P02T-00 fit: Both models share the same 10.9V battery rail, connector pinout, and BMS handshake protocol — a single cell pack covers both variants without modification.
- Bench tested on actual hardware: We cycled this battery through the OPM-P02T boot sequence and confirmed the BMS initialised correctly, passed the device's internal self-test, and reported state-of-charge accurately to the display within one full charge-discharge cycle.
- Post-swap power-on procedure: After installing this battery, let the device complete its full power-on self-test without interruption. Medical-grade BMS firmware runs a verification routine at startup — cutting power during this sequence logs a persistent battery fault that will not clear until the next clean reboot.
OPM-P02T alarming low battery immediately after a confirmed full charge
The OPM-P02T sets its low-battery alarm threshold against internal BMS state-of-charge registers, not raw terminal voltage. On a new cell, those registers haven't been calibrated to the actual capacity yet, so the device reads an artificially low state-of-charge and trips the alarm even when the pack is physically full. One complete charge-discharge cycle writes corrected data to the BMS registers. After that cycle, the alarm clears and the device reads accurately.
Device not completing boot sequence after battery sat in storage
Li-ion cells self-discharge during storage. If the OPM-P02T battery dropped below approximately 9V — the BMS recovery threshold for this pack — the protection circuit will have opened the output and the device will not respond to the power button at all. Connect the charger and leave it for at least 30 minutes before pressing power. The charge IC applies a low-rate recovery current first, and the BMS will close the output circuit once cell voltage climbs back above the recovery floor.