Fujitsu LifeBook CH75/E3 Replacement Battery 15.4V 3400mAh

Fujitsu LifeBook CH75/E3 Series — 15.4V Li-Polymer Replacement Battery (CP790491-01)

This is a 15.4V, 3400mAh (52.36Wh) lithium-polymer battery for the Fujitsu LifeBook CH75/E3, CH90/E3, WC1/E3, and WC2/E3 tablets. It replaces OEM part numbers CP790491-01, CP790492-01, FPB0356, FPB0357, GC020028M00, and GC020028N00. Same voltage, same form factor, same connector orientation as the factory cell.

• CH75/E3, CH90/E3, WC1/E3, WC2/E3 fit: All four LifeBook models share the same 15.4V battery rail, connector pinout, and BMS handshake protocol — one cell covers the entire platform. The BMS negotiation is identical across these variants, so the charge IC accepts this battery without a firmware conflict.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the LifeBook platform. The BMS accepted the cell on first insertion, the charge IC stepped through CC/CV phases cleanly, and no protection fault codes triggered during the test cycle.
• Fuel gauge reset after installation: After fitting this battery, run the tablet down to automatic shutoff, then charge uninterrupted to 100% without using the device. This single full cycle resets the fuel gauge IC calibration against the new cell and clears the inaccurate percentage readings that appear immediately after a swap.

Why the LifeBook CH75/E3 shuts down at 15–25% remaining

When the display backlight and WiFi radio pull current simultaneously, the combined load creates a short voltage sag at the cell terminals. If the BMS reads that dip as a low-voltage cutoff event, it trips the protection circuit and shuts the tablet down — even though the gauge still shows charge remaining. This happens more often with a degraded cell, but it can also occur on a new battery whose fuel gauge is still calibrated to the old cell's discharge curve. Running one full discharge-to-shutoff cycle recalibrates the gauge and typically eliminates these early cutoffs.

Fast charging not available after battery swap

After fitting a replacement cell, the LifeBook's charge IC may default to standard charge rates until it completes one accepted USB-PD negotiation cycle with the new battery in the circuit. The charge controller re-evaluates cell impedance and temperature response during the first full charge before it unlocks higher charge rates. If fast charge still does not appear after one full cycle, check that the USB-PD adapter is connected directly — not through a hub or dock — and confirm the cable supports full power delivery. A direct connection to a USB-PD charger rated at 45W or above resolves this in most cases.