Samsung SPH-A650 Replacement Battery BST195ASE 3.7V 1000mAh

Samsung SPH-A650 / SPH-A655 — 3.7V Li-ion Replacement Battery (BST195ASE)

This is a 3.7V, 1000mAh Li-ion cell built to the BST195ASE specification for the Samsung SPH-A650 and SPH-A655 handsets. It fits the original battery bay with no modification. Voltage and connector match the original Samsung spec exactly.

• SPH-A650 and SPH-A655 compatibility: Both models run the same 3.7V single-cell architecture and share the BST195ASE footprint, connector pitch, and BMS handshake requirements — so one cell covers both variants without adaptation.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SPH-A650 platform. The BMS accepted charge current without fault codes, and the protection circuit triggered correctly at the low-voltage cutoff threshold during deep discharge testing.
• Fuel gauge recalibration on first install: After fitting this cell, run one complete discharge to automatic shutdown followed by a full uninterrupted charge before using the phone normally. This lets the fuel gauge IC map its coulomb counter to the new cell's actual discharge curve — skipping this step causes erratic percentage readings for the first several days.

Why the SPH-A650 reports wrong battery percentage after a cell swap

The SPH-A650 uses a fuel gauge IC that builds its state-of-charge model against the discharge curve of the cell it has been cycling. When a new cell goes in, the IC is still referencing the old degraded cell's curve. The mismatch produces percentage readings that jump, plateau, or drop faster than the real charge level. One full discharge-to-shutdown followed by a full charge resets the coulomb counter and lets the IC re-anchor to the new cell. After that single cycle, percentage tracking stabilises.

Sudden shutdown at 20–25% on the replacement cell

This happens when the fuel gauge IC has not yet recalibrated to the new cell and cuts power based on a voltage threshold mapped to the old, degraded curve. The new cell hits a voltage cliff under the load of the radio or backlight before the gauge reaches 0%. The phone interprets this as a fault and shuts down to protect the BMS. Force a full discharge cycle — let the phone run to automatic shutdown from a full charge — and the gauge IC will reset its low-voltage floor to match the new cell. After calibration, shutdown should not occur above 3.4V.