Maibenben 4S Replacement Battery 14.8V 4000mAh Li-Polymer

Maibenben 4S — 14.8V Li-Polymer Replacement Battery

This is a 14.8V, 4000mAh (59.2Wh) Li-Polymer replacement battery for the Maibenben 4S laptop. It fits the 4S notebook directly and restores full unplugged operation when the original cell has degraded or failed to hold charge. Voltage and capacity match the original specification.

• Maibenben 4S compatibility: The 4S platform draws from a single battery rail at 14.8V with a four-cell Li-Polymer configuration. This replacement matches that cell count and voltage, so the BMS handshake between battery and motherboard completes without fault codes.
• Bench tested on actual hardware: We cycled this cell through charge and discharge under CPU and display load. The BMS held cutoff at the correct low-voltage threshold and the charge controller brought it to 100% without interruption or thermal event.
• First-cycle reset on the 4S: After fitting this battery, run the laptop down to hibernate cutoff on a normal workload, then charge it uninterrupted to 100% without using the machine. This forces the BIOS learn cycle to register the new cell and clears the inaccurate health warning that appears after every cell swap on this platform.

Why the Maibenben 4S BIOS reports poor battery health after a cell swap

The BIOS on the 4S reads health data from EEPROM stored in the original battery pack — not from live cell measurements. When a new cell goes in, that EEPROM data is gone, and the firmware flags the pack as degraded because it has no charge history to reference. This is not a fault with the replacement cell. Running one complete discharge-to-hibernate then an uninterrupted full charge gives the BIOS enough data to recalibrate and clear the warning. After two or three cycles the health readout stabilises.

Laptop shutting down at 20–30% remaining after the battery swap

This happens when the fuel gauge IC on the motherboard is still calibrated to the wear curve of the old, degraded cell. The gauge predicts a voltage cliff at 20–30% because that is where the old cell actually failed under load. The new cell can sustain voltage well below that point, but the firmware does not know it yet. Run two full discharge cycles down to hibernate cutoff and the fuel gauge IC will recalibrate against the new cell's actual voltage curve — shutdowns at false-low readings stop after that.