About this replacement
Emporia Pure / V25 Series — 3.7V Li-ion Replacement Battery (AK-V25)
This is a 3.7V, 1050mAh Li-ion cell that fits the Emporia Pure, V25, V25_001, and EUPHORIA handsets. It is a direct swap for the original AK-V25 cell when the existing battery no longer holds adequate charge. Voltage and cell dimensions match the OEM specification: 66.45 × 42.13 × 4.05mm.
- Pure / V25 platform fit: These models share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail. The AK-V25 part number covers both the original and V2.0 revision — both use the same mechanical and electrical interface, so one cell fits all variants listed.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the V25 platform. The BMS accepted the charge handshake without fault codes, and the protection circuit tripped correctly at low-voltage cutoff — no thermal events during the test cycle.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell — otherwise the percentage readout will drift early.
Sudden shutdown at 20–30% on the Emporia Pure after a cell swap
This is a voltage-cliff issue, not a defective cell. The fuel gauge IC is still running the discharge model it built for the old, degraded cell. When the new cell hits roughly 3.6–3.7V under screen or modem load, the phone's power manager sees a voltage drop it interprets as near-empty and cuts off. One full discharge-to-low-battery-warning cycle followed by a complete charge resets the coulomb counter and maps the new cell's actual discharge curve — shutdowns at false percentages stop after that cycle.
Phone feels warm near the battery during the first charge after replacement
A new Li-ion cell has higher internal impedance than a worn cell. During the first charge cycle, the charge IC delivers current into that higher impedance, and some of the energy converts to heat rather than stored charge. This is normal for the first one or two cycles as the cell's impedance settles. If warmth continues past the second full charge cycle, check that the back cover is fully seated — a gap traps heat and prevents normal passive dissipation. Surface temperature should be below 40°C within the first 20 minutes of charging.