Evolveo StrongPhone Accu Compatible Battery 3.7V 2600mAh

Evolveo StrongPhone Accu — 3.7V Li-Polymer Replacement Battery (StrongPhone Accu)

This 3.7V 2600mAh Li-Polymer cell is a direct replacement for the Evolveo StrongPhone Accu smartphone. It restores power to phones where the original cell has degraded, swelled, or no longer holds charge. Voltage and capacity match the original specification: 3.7V nominal, 2600mAh (9.62Wh).

• StrongPhone Accu fit: The StrongPhone Accu uses a slim Li-Polymer pouch cell at 3.7V with a dedicated BMS board. This replacement cell matches the 72.22 × 35.90 × 12.44mm footprint and connects to the same BMS, so the phone's charge IC sees the correct cell impedance from the first charge cycle.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS accepted the cell without triggering overcurrent or overvoltage cutoffs, and the charge IC brought the cell up to 4.2V within normal termination parameters.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC build an accurate discharge curve against the new cell before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the replacement cell

This happens because the fuel gauge IC is still running the discharge curve it mapped to the old, degraded cell. A new cell has a steeper voltage drop near the tail end of discharge — the phone hits its low-voltage cutoff at what the gauge still reads as 20–30%. The fix is one full discharge cycle from 100% down to automatic shutdown, then a full charge without interruption. After that cycle, the coulomb counter recalibrates and percentage readings stabilise.

Device not powering on after the battery sat in storage

Li-Polymer cells that have self-discharged below approximately 2.5V per cell will trigger BMS lockout — the protection circuit opens and blocks current flow to prevent damage. The phone shows no response: no boot screen, no charge indicator. To recover, connect the charger and leave it undisturbed for 15–20 minutes — the charge IC trickle-charges the cell up from the floor voltage until the BMS re-arms. Once the cell reaches roughly 3.0V, the BMS closes and normal charging resumes.