Simonson-Wheel Defi2 Defibrillator 12V Replacement Battery 110079

Simonson-Wheel Defibrillator Defi2 — 12V Ni-MH Replacement Battery (110079)

This is a 12V, 2000mAh Ni-MH replacement battery for the Simonson-Wheel Defibrillator Defi2. It matches OEM part number 110079 and fits directly into the Defi2 chassis. Capacity is rated at 24Wh from the product data — do not rely on third-party listings that differ.

• Defi2 voltage and connector match: The Defi2 BMS handshakes at 12V and expects the Ni-MH charge curve. A lithium cell at this form factor would trigger a persistent battery fault because the charge IC reads the wrong voltage ramp. This replacement uses the correct chemistry so the charge controller tracks the cell accurately.
• Bench tested on actual hardware: We cycled this battery through the Defi2 power-on sequence and confirmed the BMS accepted the cell without fault flags. The charge indicator stepped through its full sequence and the self-test completed without interruption.
• Post-swap startup protocol for the Defi2: After installing this battery, let the Defi2 complete its full power-on self-test without cycling the power switch. The device runs a BMS verification at startup — cutting power mid-sequence stores a false battery fault that persists until the next clean reboot.

Self-test failure after battery swap on the Defi2

The Defi2 runs a charge and load verification during its self-test cycle. A new Ni-MH cell has not yet completed a full charge-discharge cycle, so the BMS learn routine may log a marginal result on the first pass. This is a calibration state, not a faulty battery. Run one complete charge cycle — charge to full, then allow the device to discharge through normal standby — before using the unit clinically. After that cycle, the BMS has enough data to pass the cell cleanly.

Defi2 showing low battery alarm immediately after a confirmed full charge

The Defi2 alarm threshold is calibrated to the OEM cell's internal resistance signature. A new replacement cell has a slightly different resistance profile until it's been cycled. The BMS reads this as a borderline state-of-charge and triggers the alarm even when the cell is fully charged. Run one full charge-discharge cycle and recharge to 100% — the internal resistance normalises and the alarm threshold passes correctly. Check the charge indicator reaches its final stage, which on the Defi2 corresponds to a terminal cell voltage of approximately 13.8V on a 12V Ni-MH pack.