Mediwatch PA-00141 Replacement Battery 12V 3600mAh

Mediwatch PA-00141 Series — 12V Ni-MH Replacement Battery (110844)

This is a 12V 3600mAh Ni-MH replacement battery for the Mediwatch PA-00141, PA-00250, and PA-00284 portable patient monitoring and diagnostic devices. It replaces OEM part numbers 110844, CSA19101, and EE090279. Capacity figures are taken directly from the product data — 43.2Wh total energy.

• PA-00141, PA-00250, PA-00284 compatibility: These models share the same 12V power rail, battery bay dimensions, and BMS handshake protocol. The connector pinout and physical footprint — 71 x 67 x 49mm — are identical across the series, so the same cell pack satisfies all three.
• Bench tested on actual hardware: We cycled this pack through a full charge and discharge on a clinical-grade load tester. The BMS passed charge acceptance, balanced cell voltage across the Ni-MH array, and held voltage above the device's low-battery threshold through the full draw cycle.
• Post-swap power-on protocol: After installing this battery, allow the device to complete its power-on self-test without interruption. Mediwatch monitors run a BMS verification routine at startup — cutting power during this sequence triggers a false battery fault that persists until the next full reboot.

Why Ni-MH cells in medical monitors need a conditioning cycle before clinical use

Ni-MH chemistry ships in a partially discharged state. The cell's internal resistance is elevated until it completes one full charge-discharge cycle. Mediwatch devices apply a conservative BMS threshold calibrated to an OEM cell that has already been conditioned — a new, unconditioned pack may read as below threshold even at full charge. One complete cycle normalises the internal resistance and aligns the pack's voltage profile with what the BMS expects.

Charge indicator stuck below 100% on first charge

The charge IC in these monitors applies a reduced current limit when it detects a new or unfamiliar pack — this is expected behaviour, not a fault. The conservative limit causes the charge cycle to terminate early, leaving the displayed state-of-charge below 100%. Run one full discharge down to the device's automatic cutoff, then recharge from empty. After this single cycle, the charge IC recalibrates and the indicator reaches full charge correctly on subsequent cycles.