Infinum Omni II Replacement Battery XHP5Ah 11.1V 5000mAh

Infinum Omni II / Omni — 11.1V Li-ion Replacement Battery (XHP5Ah)

This 11.1V, 5000mAh (55.5Wh) Li-ion battery replaces the OEM pack in the Infinum Omni II and Omni portable oxygen concentrators. It slots directly into the battery bay and connects to the same BMS interface the device uses for charge state reporting and fault detection. Capacity figures are from the product data — 5000mAh at 11.1V nominal.

• Omni II and Omni compatibility: Both models share the same 11.1V three-cell Li-ion architecture, battery connector pinout, and BMS communication protocol. A single replacement pack covers either unit without modification.
• Bench tested on actual hardware: We ran charge and discharge cycles on this cell with the Omni's BMS active. The protection circuit responded correctly to end-of-charge termination, low-voltage cutoff, and thermal monitoring events across all test cycles.
• Post-swap self-test requirement: After installing this battery, let the Omni II complete its full power-on self-test without interruption. Medical-grade BMS firmware runs a verification sequence at startup — cutting power during this phase logs a persistent battery fault that won't clear until a clean reboot with a full charge.

Why the Omni II alarms low battery on a freshly charged replacement

The Omni II's charge IC sets a conservative acceptance threshold calibrated against OEM cell chemistry. A new third-party cell with a slightly different internal resistance profile can report a state-of-charge value the BMS treats as marginal, even at full charge. This isn't a fault with the cell — it's the BMS learning the new pack's characteristics. One full charge-to-discharge-to-full-charge cycle recalibrates the state-of-charge model and clears the alarm. Do not use the device clinically until that cycle is complete.

Omni II will not power on after the replacement battery sat in storage

Li-ion cells self-discharge during storage. If the pack voltage drops below approximately 9V (roughly 3V per cell), the Omni II's BMS enters deep-discharge lockout and blocks startup to protect the cells. The device will show no response — no lights, no boot sequence. Connect the OEM charger and leave it for at least two hours before attempting power-on; the charger applies a trickle current to lift the pack above the BMS recovery threshold before switching to normal charge rate.