Microsoft Surface Book 1938 Tablet Compatible Battery 7.6V 2200mAh

Microsoft Surface Book 1938 — 7.6V Li-Polymer Replacement Battery (M1097873-001 / MQ08)

This is a 7.6V, 2200mAh Li-Polymer battery for the tablet component of the Microsoft Surface Book 1938. It replaces OEM part numbers M1097873-001 and MQ08. When the original cell degrades, the tablet loses usable charge quickly — this battery restores the capacity the tablet portion needs to function independently from the keyboard base.

• Surface Book 1938 tablet unit fit: The 1938 tablet runs a dedicated cell separate from the keyboard base battery. This replacement matches the 7.6V nominal voltage rail and the thin 2.20mm profile required to seat correctly inside the tablet housing without clearance issues.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Surface Book 1938 tablet. The BMS accepted the charge handshake without fault flags, and voltage held stable under display-on plus Wi-Fi load.
• Fuel gauge recalibration after swap: After installation, run the tablet down to automatic shutoff, then charge uninterrupted to 100% without removing it from the charger. 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 battery swap.

Surface Book 1938 tablet shutting down at 15–25% remaining

This happens because the fuel gauge IC was calibrated to the old, degraded cell. The new cell has a steeper voltage curve in the lower charge range than the gauge expects. When display brightness is high and Wi-Fi is active simultaneously, the combined load pulls voltage down faster than the gauge tracks, triggering a low-voltage shutoff before the percentage reaches zero. Run one complete discharge-to-shutoff cycle followed by an uninterrupted charge to 100% — after that cycle, the gauge maps correctly to the new cell's actual voltage curve.

Surface Book 1938 not showing fast charge after battery replacement

Fast charging on the Surface Book relies on the charge IC completing a successful negotiation cycle with a known-good cell. On a freshly installed battery, the controller has not yet logged an accepted charge handshake. Complete one full charge from low to 100% using the original Microsoft power supply — third-party chargers can interrupt the negotiation. After that first successful cycle, the charge IC unlocks higher current delivery for subsequent sessions.