Eton ECG-1A Medical Device Replacement Battery 12V 2000mAh

Eton ECG-1A / ECG-2201 Series — 12V Ni-MH Replacement Battery (HYHB-1172)

This is the HYHB-1172 replacement battery for the Eton ECG-1A, ECG-2201G, ECG-2201, and ECG-2303B portable electrocardiograph devices. It runs at 12V with a 2000mAh (24Wh) Ni-MH cell pack. The battery slots into the device's internal bay and powers the unit during patient ECG recordings.

• ECG-1A and ECG-2201 series compatibility: These models share the same 12V power rail, connector pinout, and BMS handshake protocol, which is why a single part number covers all of them. Voltage tolerance across the pack matches what the device's charge IC expects at both full charge and cutoff.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a calibrated load matching the ECG's draw profile. The BMS held cutoff within spec and did not trip false-low during the load transitions that occur when the ECG's signal acquisition circuit activates.
• Post-installation self-test cycle: After fitting this battery, allow the ECG device to complete its full power-on self-test without interruption. The device runs a BMS verification sequence at startup — cutting power mid-sequence flags a persistent battery fault that does not clear until the next complete reboot.

Why the ECG-1A reports a battery fault after a confirmed full charge

The ECG-1A's BMS compares the incoming cell's charge curve against a stored OEM reference profile. A new Ni-MH pack has not yet established a consistent delta-peak signature, so the BMS can misread charge termination and flag a fault. This is a chemistry calibration gap, not a defective cell. Running one complete charge-discharge cycle lets the BMS update its reference and clears the fault on subsequent charges. After that first cycle, the charge indicator and fault status behave normally.

Device shuts off mid-recording during the first few uses

New Ni-MH cells have higher internal resistance in the first several cycles, and the ECG's load profile during active signal acquisition draws enough current to cause a brief voltage sag. If that sag drops below the BMS low-voltage cutoff threshold — typically around 9.6V on a 12V Ni-MH pack — the device shuts off as a protection event, not a capacity failure. This resolves progressively over the first eight to ten charge-discharge cycles as internal resistance drops and the pack reaches full electrochemical conditioning. Do not use this battery for clinical recordings until it has completed those conditioning cycles.