T-Mobile Evolve Compatible Battery 3.7V 1300mAh Li-ion

T-Mobile Evolve / Evolve 3G — 3.7V Li-ion 1300mAh Replacement Battery

This is a 3.7V, 1300mAh Li-ion replacement battery for the T-Mobile Evolve and Evolve 3G smartphones. It restores power to a phone whose original cell has degraded and can no longer hold a usable charge. Capacity matches the factory spec at 1300mAh (4.81Wh).

• Evolve and Evolve 3G fit: Both the Evolve and Evolve 3G share the same battery bay dimensions and voltage rail. The cell footprint is 64.18 × 49.95 × 4.15mm — either model accepts this cell without modification to the connector or housing.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge sequences on the Evolve platform. The BMS held charge termination correctly at 4.2V and low-voltage cutoff triggered before the cell reached damaging depth.
• Fuel gauge recalibration after swap: On first use after installation, disable fast charging if available and run one full discharge-to-charge cycle. The fuel gauge IC on the Evolve is calibrated to the old cell's discharge curve — one complete cycle lets it reset its reference before normal charging resumes.

Sudden shutdown at 20–30% on the replacement cell

This is the most common complaint after a cell swap on the Evolve. The fuel gauge IC still holds the old cell's voltage-to-capacity map, so it reports 25% remaining while the actual cell voltage has already dropped below the threshold the modem and display need to stay on. The phone cuts out not because the battery is faulty but because real voltage under load hits the hardware floor before the gauge catches up. One full discharge cycle — letting the phone run down to auto-shutdown, then charging uninterrupted to 100% — resets the coulomb counter and clears this behaviour.

Phone warm near the battery during the first few charges

A new Li-ion cell has higher internal impedance than a broken-in cell. During the first one or two charge cycles, the charge IC pushes current into that higher-impedance cell and generates more heat than you'd see with a worn-in battery. This is normal and reduces as the cell conditions. If the back of the phone stays noticeably warm past the third full charge, check that no background apps are holding a wake lock — that load on top of charging amplifies heat on a fresh cell. Confirm charge termination by watching the indicator drop to trickle at 4.2V.