WEGO P12n Oxygen Concentrator Replacement Battery 7.4V 7800mAh

WEGO P12n / Surpass P12N — 7.4V Li-ion Replacement Battery (SPQDCY2S3P)

This is a 7.4V 7800mAh (57.72Wh) Li-ion replacement battery for the WEGO P12n and Surpass P12N portable oxygen concentrators. It slots directly into the battery bay and powers the concentrator's compressor, control board, and alarm circuits. Capacity figures come from the product data, not estimated equivalents.

• P12n and Surpass P12N compatibility: Both models run the same 7.4V two-cell battery architecture with the SPQDCY2S3P connector and BMS handshake. Swapping between these variants does not require firmware changes or adapter hardware.
• Bench tested on actual hardware: We cycled this battery through charge and full-load discharge on a P12n unit. The BMS passed cell-balance verification at startup and held voltage above the low-battery alarm threshold through the complete discharge profile without unexpected cutoff.
• Post-swap self-test protocol: After installing this battery, let the P12n complete its full power-on self-test without interrupting the boot sequence. The concentrator's BMS runs a cell-verification routine at startup — cutting power mid-sequence creates a latched battery fault that will persist until the next clean reboot cycle.

Why the P12n triggers a low-battery alarm on a freshly charged replacement

The P12n's charge-monitoring IC applies a conservative acceptance threshold calibrated to a broken-in OEM cell. A new cell's internal resistance reads slightly higher than that baseline on the first charge cycle, and the device interprets this as a degraded or undercharged pack. Run one full charge-to-discharge cycle before using the battery in a clinical setting. After that cycle, the BMS recalibrates its reference point and the alarm clears.

P12n will not power on after the battery has been sitting in storage

Li-ion cells self-discharge at roughly 2–3% per month. If this battery has been stored long enough to drop below the BMS recovery threshold — typically around 2.5V per cell — the concentrator's protection circuit will refuse to initialise and the unit will show no response at the power button. Connect the battery to a known-good charger and allow a full charge before attempting to power on the device. If the charger shows activity and reaches a green or full indicator, try the power-on sequence again at that point.