Virgin Mobile C5133 Replacement Battery 3.7V 1400mAh

Virgin Mobile C5133 / C5133 Event — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1400mAh Li-ion battery for the Virgin Mobile C5133 and C5133 Event smartphones. It slots into the same battery bay as the original cell and connects to the same three-contact pogo strip. Voltage and physical dimensions match the OEM spec: 65.20 × 44.00 × 5.10mm.

• C5133 and C5133 Event compatibility: Both models share the same battery bay geometry, contact layout, and 3.7V nominal voltage rail. The BMS handshake on each is identical, so one cell covers both variants without modification.
• Bench tested on actual hardware: We cycled this cell on a C5133 unit and confirmed the BMS accepted the charge profile on the first cycle. Cutoff voltages held at the expected 4.2V charge ceiling and 3.0V discharge floor under screen and modem load.
• Fuel gauge recalibration on first use: Disable fast charging for the first complete discharge-charge cycle after installation. The fuel gauge IC is still calibrated to the old cell's discharge curve — running one full cycle at standard current lets it remap against the new cell before high-current charging begins.

Sudden shutdown at 20–30% on the C5133 after a cell swap

This is a voltage cliff issue, not a capacity issue. The fuel gauge IC still holds the discharge curve of the original cell in memory, so its percentage estimate drifts as the new cell ages differently. Under peak modem or display load, actual cell voltage drops below the BMS cutoff threshold before the OS has counted down to 0%. One full discharge-charge cycle at standard charge current resets the coulomb counter and brings the percentage readout back into alignment with real cell voltage.

Phone warm near the battery bay on the first charge after replacement

A new high-impedance cell presents higher internal resistance than the depleted original, so the charge IC pushes slightly more voltage to drive the same current — generating more heat at the cell surface during CC phase. This is normal on the first one or two cycles and decreases as internal resistance drops with use. If the device stays warm past the CV taper phase or the charge IC shows no current drop after reaching 4.2V, seat the battery contacts again and confirm the connector is fully engaged. Heat should be minimal by the third full charge cycle.