About this replacement
Motorola Moto E / XT1021 / XT1025 — 3.8V Li-Polymer Replacement Battery (BL40)
This is a 3.8V, 1980mAh lithium-polymer battery that replaces the OEM BL40 cell in the Motorola Moto E series. It fits the XT1021, XT1025, Moto E Dual TV, and related variants. The battery powers the processor, display, cellular radio, and all background services on these devices.
- XT1021 / XT1025 / Moto E Dual TV compatibility: These models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. One BL40 cell covers the full group without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a Moto E unit. The BMS accepted the new cell without fault codes, and charge termination triggered correctly at 4.35V.
- Fuel gauge recalibration after swap: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.
Sudden shutdown at 20–30% on the Moto E after a cell swap
This happens because the fuel gauge IC is still calibrated to the old cell's voltage-versus-capacity curve. The new cell hits a steeper voltage cliff under modem or display load, and the IC reports 25% while the actual cell voltage has already dropped below the cutoff threshold. The phone shuts down to protect the cell — the percentage shown is simply wrong at that stage. Run one full discharge to near-zero and a complete charge to 100% without interruption to let the coulomb counter re-anchor to the new cell.
Phone warm near the battery during the first few charges after replacement
A fresh high-impedance cell generates more heat than a worn one during the initial charge cycles. The charge IC applies its standard current profile, but internal resistance on a new cell is slightly higher, so more energy converts to heat before the cell is broken in. This is normal for the first three to five cycles and fades as internal resistance drops. If the phone remains warm after five full cycles, verify the charge IC is not applying a fast-charge profile by checking the charging settings under the battery menu.