About this replacement
Microsoft Surface Book 2nd 15" 1793 Keyboard — 11.36V Li-Polymer Replacement Battery (G3HTA040H)
This 11.36V, 5400mAh (61.34Wh) Li-Polymer battery replaces the G3HTA040H cell inside the detachable keyboard base of the Surface Book 2 15-inch (Model 1793). The keyboard base carries its own independent battery, separate from the tablet clipboard unit. Replacing this cell restores the extended battery capacity the keyboard base provides to the overall system.
- Surface Book 2 15" keyboard base fitment: The 1793 keyboard base uses a dedicated battery rail isolated from the clipboard display unit. The two batteries communicate charge state to Windows through separate fuel gauge ICs. This replacement targets the base unit only — it does not affect the clipboard battery.
- Bench tested on actual hardware: We ran this cell through the Surface Book 2 base BMS handshake and confirmed the charge IC accepted the new cell without flagging a fault. The base-to-clipboard power-sharing logic operated normally across both charge and discharge cycles.
- Fuel gauge recalibration after swap: After installation, run the keyboard base down to automatic shutoff through normal use, then charge uninterrupted to 100%. This one full cycle forces the fuel gauge IC to recalibrate against the new cell capacity and clears the inaccurate percentage readings that typically appear immediately after a swap.
Why the Surface Book 2 base battery percentage reads wrong after replacement
The keyboard base uses a dedicated fuel gauge IC that stores a learned capacity model for the original cell. When a new cell goes in, that stored model no longer matches the actual cell characteristics, so Windows reports an incorrect percentage. The IC needs one complete discharge-to-shutoff and uninterrupted full charge to relearn the cell's voltage curve. Until that cycle runs, readings anywhere between 10% and 40% off are normal and not a fault with the replacement cell.
Surface Book 2 base not contributing charge to the clipboard after battery swap
The Surface Book 2 uses a bi-directional power-sharing architecture where the keyboard base can charge the clipboard unit when docked. If the base battery reports below a threshold voltage — common on a new cell that shipped partially discharged — the firmware disables outbound power sharing until the base cell clears that floor. Charge the base to at least 50% via the Surface Connect port before docking and testing power-share behaviour. If sharing still does not activate, confirm the base battery voltage reads above 10.8V in the Surface app diagnostics.