Criticon Dinamap P81 Replacement Battery 4.8V 1500mAh

Criticon Dinamap P81 / P81T — 4.8V Ni-MH Replacement Battery (120446)

This is a 4.8V, 1500mAh Ni-MH replacement battery for the Criticon Dinamap P81 and P81T vital signs monitors. These portable clinical units measure blood pressure and heart rate at the bedside, running on internal battery power during patient assessments. This cell matches OEM part numbers 120446 and BATT/110446.

• Dinamap P81 and P81T compatibility: Both models share the same 4.8V battery bay, connector pinout, and BMS handshake protocol. The P81T adds trending memory but draws from the same voltage rail, so one battery SKU covers both units.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Dinamap P81 platform. The BMS accepted the cell without fault codes, completed its initialisation sequence, and held voltage above the low-battery alarm threshold through multiple discharge cycles.
• Post-swap startup protocol: After installing this battery, allow the Dinamap to complete its full power-on self-test without interruption. The BMS runs a chemistry verification routine at boot — cutting power mid-sequence registers a false battery fault that persists until the next clean reboot.

Why the Dinamap P81 alarms low battery immediately after a confirmed full charge

The P81's BMS stores a charge profile from the previous cell and compares the new cell's voltage rise curve against it during the first charge cycle. A fresh Ni-MH cell charges slightly differently than a broken-in one, and the monitor can flag this as a fault before the cell has had a chance to establish its own baseline. Run one full charge-discharge cycle before clinical use. After that cycle, the BMS updates its reference profile and the alarm clears.

Dinamap P81 will not power on after the replacement battery sat in storage

Ni-MH cells self-discharge in storage, and if voltage drops far enough, the P81's BMS will refuse to boot — it interprets the low resting voltage as a damaged or deeply depleted cell. Connect the monitor to mains power and leave it on charge for a full uninterrupted cycle before attempting to power on from battery alone. Once the cell reaches approximately 5.4V across its full pack (1.35V per cell), the BMS clears the under-voltage lockout and normal boot resumes.