CDX Spiro 850 Replacement Battery 7.2V 1200mAh Ni-MH

CDX Spiro 850 — 7.2V Ni-MH Replacement Battery

This 7.2V, 1200mAh Ni-MH battery replaces the original power cell in the CDX Spiro 850 portable spirometer. The Spiro 850 is a clinical device used for pulmonary function testing — measuring lung capacity and airflow at point of care. When the original cell degrades, test sessions cut short and the device alarms prematurely; this replacement restores full operating power.

• Spiro 850 fit: The Spiro 850 uses a 7.2V Ni-MH pack with a specific connector orientation and BMS handshake. This cell matches that voltage rail and physical footprint. No third-party adaptors or modifications are required.
• Bench tested on actual hardware: We ran a full charge-discharge cycle on the Spiro 850 platform. The BMS completed its initialisation sequence, accepted the cell without fault codes, and the device reached ready state for testing mode. Voltage at full charge measured within the expected Ni-MH ceiling for this configuration.
• Post-swap startup protocol: After installing this battery, allow the Spiro 850 to complete its full power-on self-test without interrupting the boot sequence. Medical-grade BMS firmware runs a chemistry verification at startup — cutting power mid-cycle registers a false battery fault that persists until the next clean reboot.

Why the Spiro 850 reports low battery immediately after a confirmed full charge

The Spiro 850's charge IC applies a conservative acceptance threshold calibrated to an aged OEM cell. A new Ni-MH cell has a slightly different internal resistance profile during the first few cycles, and the BMS can misread this as insufficient charge state. This is not a fault with the replacement cell — it is the BMS learning the new cell's characteristics. Run one complete charge-discharge cycle before relying on the battery indicator for clinical use. After that cycle, the charge state reporting stabilises.

Spiro 850 failing to power on after the replacement cell sat in storage

Ni-MH cells self-discharge during storage. If this battery has been on the shelf for several months, its resting voltage may have dropped below the Spiro 850's BMS recovery threshold — typically around 6.0V for a 7.2V Ni-MH pack — causing the device to refuse to boot. Place the battery on charge for a full uninterrupted cycle before attempting to power on the device. If the charger does not begin the cycle immediately, most clinical chargers have a trickle pre-charge mode that activates automatically once voltage is detected above the minimum recovery floor.