BQ Aquaris E4 B46 Replacement Battery 3.8V 1700mAh

BQ Aquaris E4 — 3.8V Li-Polymer Replacement Battery (B46)

This is a 3.8V, 1700mAh Li-Polymer battery for the BQ Aquaris E4 smartphone. It replaces part number B46 — the original cell used in this Android handset. Fit this when the existing battery holds little charge, swells, or fails to power the device entirely.

• Aquaris E4 fit: The E4 uses a compact Li-Polymer cell at 3.8V nominal with a specific connector orientation and a BMS that talks directly to the phone's charge IC. This replacement matches those electrical and physical specs — 56.60 × 52.40 × 4.80mm — so the cell seats correctly against the motherboard connector without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the E4 platform. The BMS accepted charge from the phone's onboard charge IC without fault codes, and the protection circuit tripped correctly at low-voltage cutoff.
• Fuel gauge recalibration after swap: After fitting this cell, run one full discharge down to auto power-off, then charge uninterrupted to 100% before using the phone normally. This gives the fuel gauge IC one clean cycle to map the new cell's discharge curve — skipping it causes the percentage counter to read inaccurately for days.

Sudden shutdown at 20–30% on the Aquaris E4

This happens when the cell voltage drops sharply under load before the fuel gauge reads zero. On the E4, the modem and display pull current simultaneously during calls or video, and a degraded or uncalibrated cell cannot hold voltage above the BMS cutoff threshold at those draw levels. The phone shuts down even though the reported percentage still looks reasonable. After fitting a new cell, run the full recalibration cycle described above — one complete discharge and charge — and the shutdowns stop once the coulomb counter is tracking the actual cell curve.

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

A new Li-Polymer cell has higher internal impedance than a broken-in one, so the charge IC on the E4 dissipates slightly more heat during the first one or two charge cycles. This is normal and settles after the cell completes its initial cycles. If warmth continues beyond the third full charge, check that the replacement cell is seated flat with no gap between the cell and the back cover — a raised cell can trap heat. Surface temperature should not exceed roughly 38–40°C during normal charging.