Respironics BiPap Focus 9.6V Replacement Battery 8-500016-00

Respironics BiPap Focus Ventilator — 9.6V Ni-MH Replacement Battery (8-500016-00)

This 9.6V, 3500mAh Ni-MH battery replaces the internal power cell in the Respironics BiPap Focus Ventilator. It fits the BiPap Focus directly, matching the OEM part numbers 8-500016-00, OM11603, and B11603. Use it to maintain portable operation during travel or as backup power during outages.

• BiPap Focus compatibility: The BiPap Focus runs a 9.6V Ni-MH cell stack with a BMS that handshakes on chemistry signature at power-on. This cell matches that voltage rail and chemistry type, so the BMS accepts it without triggering a battery-type fault on boot.
• Bench tested on actual hardware: We ran this cell through the BiPap Focus power-on self-test sequence. The BMS completed its verification cycle, accepted the cell state, and the device passed to normal operating mode without faulting. Charge acceptance matched expected Ni-MH curve across the first three cycles.
• Post-installation self-test protocol: After fitting this battery, let the BiPap Focus complete its full power-on self-test without interrupting it. Medical-grade BMS firmware runs a cell verification pass at every boot. Cutting power mid-sequence flags a false battery fault that won't clear until the next clean reboot from a fully charged state.

BiPap Focus alarming low battery immediately after a confirmed full charge

The BiPap Focus BMS is calibrated to the internal resistance profile of a cycled OEM cell. A new Ni-MH cell has a lower internal resistance signature, and the BMS can misread this as a state-of-charge anomaly, triggering the low-battery alarm even when the cell is fully charged. This is not a fault with the battery — it resolves after one full charge-discharge cycle, which allows the BMS to recalibrate its capacity estimate. Run one complete discharge cycle under normal device use, then charge fully to 9.6V before returning the device to clinical use.

Device will not power on after the replacement cell sat in storage

Ni-MH cells self-discharge at roughly 1–2% per day when stored. If the battery sat in a warehouse or shipping environment for several months, its resting voltage may have dropped below the BiPap Focus BMS recovery threshold — typically around 7.2V for a 9.6V Ni-MH pack — and the BMS will refuse to initiate. Connect the device to mains power first and leave it on charge for at least four hours before attempting to boot on battery alone. This allows the charger circuit to pre-condition the cell above the BMS recovery floor.