Sprint SCH-M580 Replacement Battery 3.7V 1500mAh Li-ion

Sprint SCH-M580 / Replenish / SPH-M930 — 3.7V Li-ion Replacement Battery

This 3.7V, 1500mAh Li-ion cell replaces the original battery in the Sprint SCH-M580, Replenish, and SPH-M930 handsets. All three share the same battery footprint, connector, and charge profile. Dimensions are 64.60 × 43.90 × 5.20mm — measure your original before fitting if unsure.

• SCH-M580, Replenish, and SPH-M930 compatibility: These three Sprint handsets use the same battery bay geometry and the same 3.7V charge termination voltage. One cell covers all three without any modification to contacts or housing.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SCH-M580 platform. The BMS accepted the charge handshake on the first cycle, and the protection circuit tripped correctly at the low-voltage cutoff threshold during discharge stress testing.
• Fuel gauge recalibration on first use: Disable fast charging if your device supports it for the first full discharge-charge cycle. The fuel gauge IC on these handsets calibrates against the cell's discharge curve on that first cycle — running a high current into an uncalibrated cell causes percentage drift for weeks afterward.

Why the SCH-M580 reports wrong battery percentage after a cell swap

The fuel gauge IC on this handset tracks charge state using a coulomb counter that was calibrated to the original cell's internal resistance and discharge curve. When you fit a new cell, that learned curve no longer matches the hardware. The OS reads a stale internal model and displays percentages that don't reflect actual charge. One full discharge down to auto-shutoff, followed by an uninterrupted charge to 100%, forces the IC to re-anchor its model to the new cell. After that single cycle, reported percentage stabilises.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff issue, not a capacity problem. Under modem load or screen-on bursts, a fresh cell with an uncalibrated fuel gauge can show 25% while actual terminal voltage has already dropped below the shutdown threshold. The BMS cuts power before the OS can warn you. The fix is the same: run one complete discharge-charge cycle without interruption so the coulomb counter locks onto the new cell's real voltage-to-capacity curve. If shutdowns persist past two full cycles, check that the battery contacts in the bay are clean and making solid contact — a high-resistance connection causes the same voltage sag symptom.