Virgin Mobile 101 Li-ion Replacement Battery 3.7V 950mAh

Virgin Mobile 101 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 950mAh Li-ion battery for the Virgin Mobile 101 mobile phone. It replaces the original cell when the existing battery no longer holds a charge or fails to power the device. Voltage and capacity match the OEM specification exactly.

• Virgin Mobile 101 fit: The 101 runs a single-cell 3.7V Li-ion architecture. This replacement matches that voltage rail and physical footprint — 62.65 × 38.90 × 4.90mm — so the cell seats correctly in the battery bay without modification.
• Bench tested on actual hardware: We cycled this cell through a full discharge and charge sequence, monitoring BMS cutoff at the low-voltage threshold and charge termination at capacity. The protection circuit tripped correctly at both ends with no anomalies logged.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge down to automatic shutdown before recharging. The phone's fuel gauge IC calibrated its curve to the old cell — one full cycle lets it relearn the new cell's actual discharge profile before reporting accurate percentages.

Why the Virgin Mobile 101 reports wrong battery percentage after a cell swap

The 101'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 IC reads voltage and maps it to the old curve, producing percentage figures that are off — sometimes significantly. One full discharge-to-shutdown cycle followed by a full charge forces the IC to rebuild its model against the new cell's actual behaviour.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops below the phone's minimum operating threshold under load — even though the displayed percentage suggests charge remains. The fuel gauge IC hasn't recalibrated yet, so it misreads remaining capacity. Under modem or display load, the actual cell voltage sags past the cutoff point before the percentage reaches zero. Run one full discharge cycle to recalibrate; after that, the reported percentage and actual voltage floor align. If shutdowns continue after two full cycles, check that the cell is seated flat with no gap at the connector — a loose contact causes voltage drop under load.