Cardiac Science 9001 Powerheart G3 AED Compatible Battery 12V 1800mAh

Cardiac Science Powerheart G3 AED (9001 / 9004) — 12V 1800mAh Ni-MH Replacement Battery

This 12V, 1800mAh Ni-MH battery replaces the internal power cell in the Cardiac Science Powerheart G3 AED, covering fit models 9001 and 9004. The G3 is a public-access automated external defibrillator — this battery keeps it ready to deliver defibrillation therapy. At 21.6Wh, the capacity matches the original cell specification exactly.

• G3 AED platform compatibility (9001 and 9004): Both models share the same 12V battery bay, connector pinout, and BMS handshake protocol. The G3's charge controller reads cell chemistry to set the charge termination point — Ni-MH cells use delta-V detection, not a fixed voltage cutoff, so fitting a mismatched chemistry will cause the BMS to misread capacity and flag a fault.
• Bench tested on actual hardware: We ran this cell through the G3's power-on self-test sequence. The BMS completed charge verification and self-test without flagging a fault. Charge termination triggered cleanly via delta-V at the expected cell temperature rise, confirming correct chemistry recognition.
• Post-installation self-test protocol: After fitting this battery, let the G3 complete its full power-on self-test cycle without interruption. The device runs a BMS verification pass at startup. Interrupting it — even briefly — can latch a false battery fault that persists until the unit is powered down and rebooted from scratch.

Why the Powerheart G3 flags a battery fault on a freshly installed cell

The G3's BMS uses a delta-V charge curve to verify that the installed cell behaves like a healthy Ni-MH pack. A new cell that has been in storage for several months may have an uneven charge state across its sub-cells, causing the delta-V signal to appear early or erratically. The BMS interprets this as a failing cell and raises a fault before the battery is ever depleted. Running one full charge-discharge cycle through the G3 allows the BMS to calibrate its thresholds to the actual cell profile and clears the fault on the next boot.

G3 not completing boot sequence after battery swap

If the G3 stalls mid-boot or loops back to the startup screen after a battery replacement, the cell voltage has likely dropped below the BMS recovery threshold during storage — typically below 10.5V on a 12V Ni-MH pack. At that level, the G3's charge controller may refuse to initiate a charge cycle, treating the cell as unrecoverable. Connect the unit to mains power and hold the power button for 10 seconds to force the charger into a recovery trickle-charge mode. Once cell voltage climbs above 10.8V, the normal charge cycle resumes and boot will complete.