BLU Energy X Plus C826604400L Replacement Battery 3.8V 2900mAh

BLU Energy X Plus — 3.8V Li-Polymer Replacement Battery (C826604400L)

This 3.8V, 2900mAh Li-Polymer cell replaces the OEM battery in the BLU Energy X Plus (E030US) and Energy X (E010Q). It restores power capacity when the original cell has degraded, swells, or no longer holds a charge. Voltage and capacity match the factory specification exactly.

• Energy X and E010Q compatibility: The Energy X Plus (E030US) and Energy X (E010Q) share the same battery bay dimensions, connector pinout, and 3.8V nominal voltage rail. Both handsets use the same charge IC and BMS handshake logic, so one cell fits both platforms without modification.
• Bench tested on actual hardware: We ran this cell through a full charge cycle on the Energy X Plus and confirmed the BMS accepted the new cell without fault flags. Charge IC communication logged cleanly at each state-of-charge threshold with no voltage reporting errors on the first completed cycle.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This allows the fuel gauge IC to map the new cell's discharge curve before high-current charging begins — preventing coulomb counter drift from day one.

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

This happens because the fuel gauge IC is still calibrated to the old cell's discharge curve. When the new cell hits a voltage cliff under modem or screen load — typically around 3.5V — the phone cuts out even though the reported percentage says 20–30%. The OS has not yet mapped where the new cell's voltage drops steeply. One full discharge from 100% to automatic shutdown, followed by a complete charge, resets the coulomb counter and aligns the percentage reporting to the actual cell curve.

Phone warm near the battery during the first two charge sessions

A new Li-Polymer cell has higher internal impedance than a broken-in cell. The charge IC on the Energy X Plus pushes current into this higher-impedance cell, generating slightly more heat than normal at the battery contact area during CC phase. This is expected and typically resolves after two to three full cycles as internal impedance settles. If the phone stays warm past the CV taper phase or shows a charge fault, check that the replacement cell's connector is fully seated — a loose pin raises contact resistance further.