About this replacement
CONTEC ECG 1201 / ECG 1201G — 14.4V Li-ion Replacement Battery (WP-18650-14.4-4400)
This is a 14.4V, 5200mAh (74.88Wh) lithium-ion battery pack for the CONTEC ECG 1201 and ECG 1201G portable 12-lead electrocardiograph. It replaces OEM part numbers WP-18650-14.4-4400, WP-18650-14.4-5200, WPC09-0092, and M05-32442L-05. The pack fits the standard battery bay on both the ECG-1201 and ECG-1201G variants.
- ECG 1201 and 1201G compatibility: Both models run the same 14.4V power rail and use the same BMS handshake protocol. The connector pinout and BMS communication lines are shared across ECG-1201 and ECG-1201G, so one pack covers all four OEM part numbers listed above.
- Bench tested on actual hardware: We cycled this pack through full charge and discharge on ECG 1201 hardware. The BMS passed communication checks on both models, charge termination triggered correctly at 16.8V, and no protection cutoffs fired under the device's normal acquisition load.
- Post-swap self-test requirement: After installing this battery, allow the ECG 1201 to complete its full power-on self-test without interruption. The device runs a BMS verification sequence at startup — cutting power during this window writes a false battery fault flag that persists until the next clean reboot cycle.
ECG 1201 not completing boot sequence on a new battery
The ECG 1201 runs a BMS learn cycle during its first few charge-discharge passes. On a fresh cell, the device's charge IC applies a conservative upper current limit until it maps the pack's internal resistance profile. If the boot sequence stalls or loops, the BMS has not yet completed its initialisation. Run one full charge to 16.8V, allow the device to discharge through a normal session, then recharge fully before clinical use.
Low battery alarm triggers immediately after a confirmed full charge
This happens when the device reads state-of-charge against thresholds calibrated to the original OEM cell chemistry. A new replacement cell has a slightly different internal resistance profile, so the fuel gauge algorithm under-reports capacity on the first cycle. The alarm clears after one complete charge-discharge cycle, which lets the BMS recalibrate its capacity baseline. Charge fully to 16.8V, run the device through a normal acquisition session, and recharge — the alarm should not return.