Simvalley SP-100 Replacement Battery 3.7V 1600mAh PX-3546

Simvalley SP-100 — 3.7V Li-ion Replacement Battery (PX-3546)

This 3.7V Li-ion cell replaces the original battery in the Simvalley SP-100 smartphone. It delivers 1600mAh (5.92Wh) of capacity and matches the physical footprint and connector of the factory cell. Install it when the original no longer holds a useful charge across a normal day of use.

• SP-100 platform fit: The SP-100 uses a compact single-cell Li-ion pack at 3.7V nominal. This replacement matches that voltage rail and the physical contact orientation the phone's charge IC expects. A mismatch in either causes the device to reject the pack or report a fault at boot.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SP-100 platform and confirmed the BMS handshake cleared correctly. The charge IC accepted the cell without error flags, and voltage held stable under screen and modem load.
• Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before it begins reporting percentage to the OS. Skipping this step causes the phone to show inaccurate percentages for the first several cycles.

Why the SP-100 reports wrong battery percentage after a cell swap

The SP-100's fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The OS reads percentage from the fuel gauge, not from raw voltage, so the displayed number drifts. One full discharge down to automatic shutdown followed by a full charge to 4.2V resets the coulomb counter and lets the IC re-learn the curve against the new cell.

Sudden shutdown at 20–30% on the SP-100

This happens when the cell voltage drops sharply under the combined load of the modem radio and display — a voltage cliff the fuel gauge did not predict. The gauge still shows 20–30% remaining, but the cell cannot sustain voltage above the protection cutoff under that current draw, so the BMS trips and the phone cuts off instantly. It is not a faulty battery — it is an uncalibrated gauge reading a new cell. Run two full discharge-charge cycles at standard rate, and the IC recalibrates the low-end cutoff threshold to match the actual cell curve.