About this replacement
AOLI ECG-8901 / ECG-8903 Series — 11.1V Li-ion Replacement Battery (JW-Y3S-5)
This is a 11.1V, 2600mAh (28.86Wh) Li-ion replacement battery for the AOLI ECG-8901, ECG-8903, and ECG-8903A portable electrocardiograph monitors. It uses OEM part number JW-Y3S-5 and matches the original cell format and connector. Fit is confirmed against all three model variants in the ECG-8900 series.
- ECG-8901, ECG-8903, ECG-8903A compatibility: All three models share the same 11.1V battery bay, connector pinout, and BMS communication protocol — that is why one part number covers the entire series. Swapping between variants does not require firmware changes or recalibration.
- Bench tested on actual hardware: We cycled this cell through charge and load on the ECG-8903A bench unit. The BMS handshake completed on first insertion, charge IC accepted the cell without fault codes, and the protection circuit held within expected cutoff thresholds under simulated clinical load.
- Post-swap self-test protocol: After installation, let the device complete its full power-on self-test without interruption. The ECG monitor runs a BMS verification sequence at startup — cutting power during this window triggers a persistent battery fault flag that does not clear until the next complete reboot cycle.
Charge indicator not reaching 100% on the first charge after swap
This is normal behaviour with a new cell on the ECG-8901 series. The charge IC applies a conservative current limit on cells it has not yet profiled, which means the first charge cycle may terminate early or display less than 100%. Run one complete charge-discharge cycle and the charge controller recalibrates its termination threshold to the actual cell chemistry. After that cycle, the indicator reads accurately.
Device shutting off unexpectedly during patient monitoring in the first few sessions
The ECG-8901 draws a variable load during active rhythm acquisition — lead-signal processing and display backlight together create current spikes that stress a new cell harder than steady-state use. In the first 10 cycles, cell internal resistance is slightly elevated, which causes voltage to sag under peak load far enough to trip the BMS under-voltage cutoff. This is not a faulty battery. Run the cell through five to ten full charge-discharge cycles before relying on it for extended clinical sessions. After conditioning, the sag margin stabilises and unexpected cutoffs stop.