1300-3513 Sony Ericsson Xperia X Replacement Battery 3.8V 2700mAh

Sony Ericsson Xperia X / Xperia X Dual — 3.8V Li-Polymer Replacement Battery (1300-3513)

This is a 3.8V, 2700mAh Li-Polymer replacement battery for the Sony Ericsson Xperia X and Xperia X Dual smartphones (F5121, F5122). It replaces OEM part numbers 1300-3513 and LIS1624ERPC. Swap it in when the original cell no longer holds a charge or shuts down unexpectedly under load.

• F5121 and F5122 compatibility: Both the single-SIM F5121 and dual-SIM F5122 use the same battery bay, connector, and BMS handshake protocol — one cell fits both variants without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an F5121 unit. The BMS accepted the cell, reported voltage correctly, and Qualcomm Quick Charge negotiation completed without error on the second full cycle.
• Fuel gauge recalibration on first install: On first use after installation, disable fast charging and complete one full discharge-to-charge cycle. This allows the fuel gauge IC to recalibrate its coulomb counter against the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the Xperia X after a cell swap

This is a voltage cliff issue, not a capacity problem. When the modem transmits or the display peaks, current draw spikes sharply. A new cell with an uncalibrated fuel gauge IC can report 25% remaining while the actual terminal voltage has already dropped below the BMS cutoff threshold. The BMS reads that drop as a protection event and cuts power. One full discharge-charge cycle lets the coulomb counter map the new cell's actual voltage curve, which corrects the premature cutoff.

Phone warm near the battery during the first few charges after replacement

A new Li-Polymer cell has higher internal impedance than a well-cycled cell. The charge IC on the Xperia X compensates by pushing slightly more voltage to overcome that resistance, which generates more heat than you'd see on a broken-in cell. This is normal for the first three to five charge cycles as impedance drops toward its steady-state value. If the device stays warm beyond that point or the back panel feels hot to the touch, check that the thermal pad between the cell and the chassis is seated correctly after reassembly.