Maibenben S436 Replacement Battery 11.4V 4100mAh Li-Polymer

Maibenben S436 — 11.4V Li-Polymer Replacement Battery (PF4WN-00-17-3S1P-0)

This 11.4V, 4100mAh (46.74Wh) Li-Polymer cell replaces the original battery in the Maibenben S436 notebook. It matches the OEM voltage rail, connector pinout, and physical footprint of the S436 battery bay. Cross-compatible part numbers include PF4WN-00-17-3S1P-0, PF4WN-03-17-3S1P-0, and U45A1HPFS01.

• S436 platform fit: All three OEM part numbers listed above share the same 3S1P cell configuration, 11.4V nominal rail, and BMS handshake protocol on the S436 motherboard — swapping between them does not require a firmware change or connector adapter.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the S436 platform. The BMS negotiated correctly with the system EC, charge current stepped down as expected at the 4.2V per-cell ceiling, and no protection-trip faults were logged during load testing.
• Post-swap calibration on the S436: After fitting this cell, run the battery down until the laptop hibernates on low-charge cutoff, then charge uninterrupted to 100%. This single full cycle resets the BIOS battery learn sequence and clears the inaccurate health or capacity warning that appears after every cell replacement on this model.

BIOS reporting poor battery health immediately after fitting the S436 replacement cell

When you swap the physical cell, the BIOS still holds EEPROM data from the old battery — cycle count, wear level, and design capacity logged against the previous unit. The firmware reads that stale data and flags health as degraded before the new cell has run a single cycle. This is not a fault with the replacement cell. One full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the battery controller to rewrite its learn data against the new cell's actual charge curve.

S436 shutting down at 20–30% charge shown on the fuel gauge

The fuel gauge IC on the S436 estimates remaining capacity against a stored model of the previous cell. A new cell with a different discharge curve hits a voltage point the gauge has not mapped, and the system reads it as critically low before the cell is actually depleted. The laptop shuts down to protect against over-discharge even though real charge remains. Run two to three full discharge-and-recharge cycles to let the fuel gauge IC recalibrate its model against the new cell — after calibration, the reported percentage should track accurately down to the 5–8% low-battery threshold.