Evolveo StrongPhone Q4 Replacement Battery SGP-Q4-BAT 3.7V

Evolveo StrongPhone Q4 — 3.7V Li-ion Replacement Battery (SGP-Q4-BAT)

This is a 3.7V, 3000mAh (11.1Wh) Li-ion replacement battery for the Evolveo StrongPhone Q4 rugged smartphone. It replaces OEM part SGP-Q4-BAT directly. Fit the new cell when the original no longer holds adequate charge or fails to power the device through normal use.

• StrongPhone Q4 fitment: The Q4 uses a fixed 3.7V single-cell architecture with a dedicated BMS that governs charge cutoff and low-voltage protection. This cell matches the connector pinout and physical footprint — 57.52 × 55.10 × 9.00mm — so it seats correctly in the battery bay without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the Q4 platform. The BMS accepted the new cell without throwing a protection-circuit lockout, and the charge IC completed a full CC/CV charge cycle cleanly to 4.2V.
• First-cycle calibration tip: After installation, disable fast charging for the first complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging is applied to an uncalibrated cell — reducing the chance of erratic percentage readings early on.

Sudden shutdown at 20–30% on the StrongPhone Q4

This happens when the cell voltage drops below what the modem or display load requires, even though the fuel gauge still reads a charge remaining. A degraded or freshly swapped cell with an uncalibrated coulomb counter will hit this voltage cliff faster than the OS expects. The BMS cuts power to protect the cell before the reported percentage reaches zero. Run two full discharge-charge cycles without fast charging — the fuel gauge IC will re-anchor its curve and the early shutdowns will stop.

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

A new cell typically has higher internal impedance than a broken-in one, which causes the charge IC to dissipate slightly more heat during the constant-current phase. This is normal on the first one or two cycles and does not indicate a fault. It resolves as the cell's impedance settles with use. If the phone remains hot beyond the second full charge, measure charge port voltage — it should not exceed 5.2V during standard charging.