About this replacement
Microsoft Surface Book 2 1835 13.5" Tablet Keyboard — 11.36V Li-Polymer Replacement Battery (G3HTA050H)
This 11.36V, 5000mAh (56.8Wh) Li-Polymer battery replaces the OEM cell in the detachable keyboard base of the Microsoft Surface Book 2 1835 13.5". It restores power to the keyboard dock, maintaining wireless input and charging pass-through when the tablet screen is separated from the base. OEM part numbers G3HTA050H and G3HTA049H both apply to this configuration.
- Surface Book 2 1835 keyboard base fitment: The 13.5" Surface Book 2 keyboard base uses a dedicated battery separate from the tablet display unit. This cell sits in the hinge base and supports the docking rail voltage handshake — the tablet draws from both units when docked, so a dead base battery affects overall system charge distribution.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the keyboard base, confirming the BMS communicates correctly with the Surface firmware. Charge acceptance, cutoff thresholds, and dock-rail handshake all responded as expected with no fault codes triggered.
- Fuel gauge recalibration after installation: After fitting this battery, run the base down to automatic shutoff, then charge uninterrupted to 100%. The fuel gauge IC calibrates against the new cell during this first full cycle, which corrects the inaccurate percentage readings that commonly appear immediately after a swap.
Why the Surface Book 2 base shows a different charge level than the tablet display unit
The Surface Book 2 runs two independent battery circuits — one in the tablet display and one in the keyboard base. Windows reports a combined percentage, but each cell has its own state of charge. A degraded or replaced base battery will skew the combined reading noticeably. After swapping the base cell, the reported percentage can look off by 10–20% until the fuel gauge IC has completed one full calibration cycle.
Surface Book 2 shutting down while docked with charge showing above 15%
This happens when the base battery voltage drops below the BMS cutoff threshold under combined load — keyboard backlight, USB-A ports, and charging current to the tablet display all draw from the base cell simultaneously. A cell with degraded capacity hits this voltage cliff faster than the fuel gauge predicts, causing a sudden shutdown before the percentage reaches zero. Replacing the base battery resolves the issue if the display unit cell tests healthy. After installation, confirm the base charges to a steady 11.36V at full capacity before docking under heavy load.