About this replacement
Google Pixel XL — 3.85V Li-Polymer Replacement Battery (B2PW2100)
This is a 3.85V, 3400mAh Li-Polymer cell for the Google Pixel XL smartphone. It fits the G-2PW2100, G-2PW2200, and G-2PW2100-021-B model variants. Drop this in when your original cell no longer holds enough charge to get through a full day.
- Pixel XL variant coverage: The G-2PW2100 and G-2PW2200 share the same battery bay dimensions, connector pinout, and BMS handshake protocol — all confirmed against OEM part numbers B2PW2100 and 35H00263-00M.
- Bench tested on actual hardware: We cycled this cell on a Pixel XL unit and confirmed the BMS handshake completed correctly, charge termination triggered at full voltage, and the fuel gauge IC accepted the new cell without throwing a hardware fault.
- First-cycle fuel gauge reset: After installation, disable fast charging and run one full discharge down to automatic shutdown, then charge uninterrupted to 100%. This gives the fuel gauge IC one clean cycle to map the new cell's discharge curve before fast charge current is applied to an uncalibrated cell.
Why the Pixel XL reports wrong battery percentage after a cell swap
The Pixel XL uses a coulomb counter IC that builds its charge model against the cell it has observed over many cycles. When you install a new cell, the IC is still running the old degraded cell's curve. This mismatch causes the percentage display to jump, stall, or report full charge when the cell is not actually full. One complete discharge-to-shutdown followed by an uninterrupted charge to 100% forces the IC to recalibrate against the new cell. After that single cycle, percentage reporting stabilises.
Sudden shutdown at 20–30% on the replacement cell
This happens when the fuel gauge IC triggers a shutdown based on the old cell's voltage cliff map — not the actual state of the new cell. The new Li-Polymer cell holds voltage well through most of its capacity curve, then drops steeply near the bottom. If the IC hasn't recalibrated, it reads that steep drop as 0% while the display still shows 20–30%. Run the first-cycle calibration described above, and confirm the cell rests at or above 3.85V open-circuit before reinstalling — a cell shipped below 3.0V per cell may need a slow pre-charge before the BMS will allow a normal charge cycle.