About this replacement
Medion Akoya S6212T Series — 15.5V Li-ion Replacement Battery (US55-4S3000-S1L5)
This is a 15.5V, 2600mAh (40.3Wh) Li-ion battery for the Medion Akoya S6212T notebook and compatible models including the MD99270, MD98453, and MD98456. It fits the original battery bay and connects to the same four-cell BMS architecture as the factory unit. Use the OEM part number US55-4S3000-S1L5 or 40046152 to verify fit against your existing cell.
- S6212T platform compatibility: The Akoya S6212T and its MD-series variants share the same 15.5V four-cell pack architecture, connector pinout, and BMS handshake protocol — which is why a single cell covers the full range of models listed.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the S6212T platform. The BMS completed a full handshake with the BIOS, charge current tapered correctly at top-of-charge, and protection circuitry triggered at the expected low-voltage cutoff.
- Post-install calibration on the S6212T: After fitting, run one full discharge down to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after swapping cells on this platform.
BIOS reporting poor battery health immediately after replacement
The Akoya S6212T BIOS reads health data stored in the old cell's EEPROM and compares it against the new cell's reported state. A fresh cell has no charge history, so the BIOS flags it as degraded — this is a data mismatch, not a faulty battery. Running one complete discharge-to-hibernate followed by a full uninterrupted charge gives the fuel gauge IC enough data to re-baseline against the new chemistry. After two or three full cycles, the health readout in both the BIOS and Windows normalises.
Laptop shuts off at 20–30% charge shown on screen
This happens when the fuel gauge IC is still calibrated to the old cell's discharge curve. The displayed percentage does not match actual cell voltage, so the system hits a low-voltage cliff before the gauge reaches zero. Under combined CPU and display load, voltage drops faster than the gauge tracks — the BIOS trips the cutoff to protect the cell. Discharge the laptop fully to hibernate, charge to 100% without interruption, and repeat twice. By the third cycle the fuel gauge curve aligns with the new cell and the early shutdowns stop.