Bird Vela 6 Hour 12V Replacement Battery 3500mAh Ni-MH

Bird Vela 6 Hour — 12V Ni-MH Replacement Battery

This is a 12V 3500mAh Ni-MH replacement battery for the Bird Vela 6 Hour portable ventilator. It fits the extended-operation variant used for patient transport and backup power continuity. Capacity is 42Wh, matching the original cell specification for this unit.

• Vela 6 Hour platform fit: The 6 Hour model runs a dedicated battery bay sized for this cell's 84.60 × 68.10 × 34.00mm footprint. The BMS on this ventilator handshakes over the connector for both charge state and fault detection — connector alignment and cell chemistry both need to match for the BMS to report status correctly.
• Bench tested on actual hardware: We ran charge and discharge cycles on this cell and confirmed the BMS accepted charge without triggering a chemistry mismatch fault. The protection circuit responded correctly to load and returned accurate state-of-charge data through the full cycle.
• Post-installation self-test protocol: After fitting this battery, allow the Vela to complete its full power-on self-test without interruption. The device runs a BMS verification sequence at startup — cutting power during this window logs a battery fault that persists until the next clean reboot, not until the next charge.

Why the Vela 6 Hour reports a battery fault after a confirmed full charge

The Vela's BMS uses learned capacity thresholds calibrated to the original cell's charge curve. A new Ni-MH cell has a slightly different voltage response during the first few cycles, which can push it outside the BMS acceptance window even at 100% charge. This triggers a fault flag rather than a chemistry error. One full charge-discharge cycle usually brings the cell's curve within the BMS threshold and clears the fault on the next startup.

Vela 6 Hour not completing boot sequence on new battery

If the cell voltage sat below 10V during storage, the Vela's BMS may not supply enough rail voltage to complete the boot sequence — the device powers on briefly, then cuts off. This is a deep-discharge recovery situation, not a dead cell. Connect the ventilator to mains power and leave the battery on charge for a full cycle before attempting battery-only boot. Once the cell recovers above the BMS recovery threshold, typically around 10.8V, the boot sequence completes normally.