Aeonmed Solo 12V 2000mAh Ni-MH Replacement Battery B0402091

Aeonmed Solo Ventilator — 12V Ni-MH Replacement Battery (B0402091)

This is a 12V, 2000mAh Ni-MH replacement battery for the Aeonmed Solo and Solo Ventilator portable oxygen concentrators. It replaces OEM part number B0402091 and restores mobile power capability to the unit. Capacity is rated at 24Wh, matching the original specification.

• Solo and Solo Ventilator compatibility: Both models share the same 12V battery bay, connector pinout, and BMS handshake protocol — one replacement covers either unit. The BMS on each reads cell chemistry and voltage to confirm a valid pack before enabling the oxygen delivery circuit.
• Bench tested on actual hardware: We cycled this battery through the Solo's BMS initialisation sequence and confirmed the charge IC recognised the Ni-MH chemistry correctly. The protection circuit held cutoff at the expected low-voltage threshold without triggering a false fault.
• Post-installation self-test cycle: After fitting this battery, let the Solo complete its full power-on self-test without interrupting it. The device runs a BMS verification pass at startup — cutting power during this sequence locks in a battery fault flag that won't clear until the next clean reboot from full charge.

Why the Solo's BMS may not accept a new Ni-MH cell immediately

Ni-MH cells ship in a partially discharged state to reduce shelf degradation. The Solo's BMS cross-checks cell voltage against an internal acceptance window calibrated to a conditioned pack. A new cell sitting below that window — typically under 10.8V resting — can trigger a battery fault or cause the device to refuse to run on battery at all. One full charge-discharge cycle raises the resting voltage into the accepted range and allows the BMS to update its capacity estimate. Do not attempt to use this battery in a clinical setting before completing that first cycle.

Charge indicator stalling below 100% on first charge

On first charge, the Solo's charge IC applies a conservative current limit when it detects a new or cold Ni-MH cell — the indicator may stall at 80–90% and appear stuck. This is the IC holding a trickle charge while it confirms the cell isn't absorbing above the thermal threshold. The cycle completes normally; it just takes longer than subsequent charges. If the indicator has not moved for more than two hours, remove the battery, allow it to rest for 10 minutes, then reinsert and restart the charge from 12.0V.