Cardio E3 14.4V Replacement Battery INR18650-4S2P 5200mAh

Cardio E3 — 14.4V Li-ion Replacement Battery (INR18650-4S2P)

This is a 14.4V, 5200mAh Li-ion battery pack for the Cardio E3 portable cardiac monitoring device. It uses a 4S2P cell configuration — four cells in series, two in parallel — matching the voltage rail and current delivery profile of the original pack. Capacity is sourced from the product specification: 5200mAh / 74.88Wh.

• E3 platform fit: The Cardio E3 uses a fixed 14.4V bus with a BMS that validates cell chemistry and pack impedance at startup. This replacement matches that voltage rail and uses the same INR18650 cell format, so the BMS handshake completes without a connector or communication mismatch.
• Bench tested on actual hardware: We cycled this pack through full charge and discharge on the E3 platform. The BMS completed its verification sequence, charge acceptance reached the expected cutoff, and the protection circuit responded correctly to simulated load spikes consistent with the device's monitoring cycles.
• Startup self-test — do not interrupt: After installing this battery, let the E3 complete its full power-on self-test without cycling power. The device runs a BMS verification routine at boot. Cutting power mid-sequence can register a false battery fault that persists across restarts until a clean full reboot clears it.

Why the Cardio E3 rejects a new battery during boot verification

The E3's BMS compares cell impedance against a stored OEM threshold during startup. A new cell's impedance sits slightly outside that calibrated window until it completes one full charge-discharge cycle. This causes the device to flag the pack as non-compliant even when the battery is fully charged. Run one complete cycle — full charge to full discharge under normal device operation — before using the unit in a clinical setting. After that cycle, impedance drops into the accepted range and the fault clears.

Charge indicator stalls below 100% on first charge

On the first charge, the E3's charge IC applies a conservative current limit to new cells, which can cause the indicator to plateau at 95–98% for an extended period before completing. This is the charge IC behaving correctly — it is conditioning the pack, not stalling. Do not interrupt the charge. Allow it to reach the full termination voltage of 16.8V (4.2V per cell across the 4S configuration) before disconnecting.