MyPhone NEXT Li-Polymer Replacement Battery 3.7V 2300mAh

MyPhone NEXT — 3.7V Li-Polymer Replacement Battery (NEXT)

This 3.7V, 2300mAh Li-Polymer cell is a direct replacement for the original battery in the MyPhone NEXT smartphone. It restores power capacity when the original cell has degraded through charge cycles. Capacity is rated at 8.51Wh and dimensions are 71.50 × 58.53 × 4.60 mm.

• MyPhone NEXT fit: This cell matches the voltage rail and physical footprint of the MyPhone NEXT. The BMS communication protocol and connector pinout align with the original unit, so the phone's charge IC accepts the new cell without modification.
• Bench tested on actual hardware: We cycled this cell through a full discharge and charge sequence on the bench. The BMS responded correctly at both the low-voltage cutoff and the charge termination threshold — no false shutdowns or abnormal charge termination during testing.
• Fuel gauge recalibration after swap: On first use after installing this cell, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map its internal model against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the MyPhone NEXT after a cell swap

The MyPhone NEXT uses a coulomb-counter fuel gauge that was calibrated against the original cell's discharge curve. After swapping to a new cell, the stored curve no longer matches reality. When the phone draws peak current — modem activity, screen brightness spikes — the new cell's voltage drops faster than the gauge predicts, and the system shuts down to protect the cell even though the reported percentage looks safe. One full discharge-charge cycle at standard charge rate resets the reference points. After calibration, the gauge tracks the new cell correctly and shutdowns at mid-range stop.

Phone feels warm near the battery during the first charge after replacement

A new Li-Polymer cell comes from storage with higher internal impedance than a fully conditioned cell. On the first charge cycle, the charge IC pushes current into a cell that has not yet reached its rated low-impedance state, generating slightly more heat than normal. This is a one-cycle event — not a fault. If the phone stays warm past the second full charge, check that the charger output does not exceed the rated input voltage for the NEXT. Use a 5V standard charger for the first two cycles and measure the battery area temperature after each session.