Hellige EKG Cardio Smart 18V Ni-MH Replacement Battery 2000mAh

Hellige EKG Cardio Smart / ES500 — 18V Ni-MH Replacement Battery

This 18V 2000mAh Ni-MH battery replaces the original power cell in the Hellige EKG Cardio Smart and ES500 portable electrocardiographs. These are compact clinical ECG units used in hospital wards and mobile cardiac monitoring. Voltage and capacity match the original at 18V and 2000mAh (36Wh).

• EKG Cardio Smart and ES500 compatibility: Both models share the same 18V battery rail, physical form factor, and BMS handshake protocol — one cell fits both units without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench, monitoring the BMS communication at each stage. The protection circuit responded correctly at both ends of the charge curve, with no false cutoff events during the test sequence.
• Post-swap power-on self-test: After installing this battery, allow the Cardio Smart to complete its full power-on self-test without interruption. The device runs a BMS verification at startup — cutting power during this sequence triggers a persistent battery fault that won't clear until the next clean reboot cycle.

Why the Cardio Smart charges to full but still alarms low battery

The Cardio Smart's charge IC applies a conservative threshold on new Ni-MH cells. On the first charge, the BMS may not accept the cell's state-of-charge report as valid because the internal resistance profile of a new cell doesn't match the learned baseline. This causes the device to flag a low battery condition even after a confirmed full charge. One complete charge-discharge cycle resets the learned baseline, and the alarm clears on the second charge.

Device won't power on after battery sat in storage

Ni-MH cells self-discharge in storage, and if the voltage drops far enough, the BMS enters a recovery lockout — it won't pass current to the device until the cell voltage climbs above the minimum recovery threshold. Place the battery on charge immediately and leave it connected for a full charge cycle without interrupting. If the charger doesn't initiate, the cell may need a brief trickle charge first — check that the charger shows any activity indicator within 10 minutes of connection. A cell that recovers will hold charge normally from that point forward.