Cingular Flip IV Compatible Battery 3.7V 1300mAh TL14H504357W

Cingular Flip IV / U102AA — 3.7V Li-ion Replacement Battery (TL14H504357W)

This is a 3.7V, 1300mAh Li-ion cell for the Cingular Flip IV and U102AA mobile phones. It replaces OEM part TL14H504357W and restores power to devices where the original cell has degraded or lost the ability to hold a charge. Dimensions are 57.50 × 43.00 × 4.80mm — confirm against your existing cell before installing.

• Flip IV and U102AA compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell fits both. The fuel gauge IC on each device reads the same charge curve, so no firmware difference affects this swap.
• Bench tested on actual hardware: We cycled this cell through a full discharge-charge sequence and monitored BMS cutoff behaviour at the low-voltage threshold. The protection circuit triggered correctly at the expected floor, and charge acceptance held steady across the full 1300mAh rated capacity.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell — preventing early percentage jumps or premature cutoffs.

Sudden shutdown at 20–30% on the Cingular Flip IV after a cell swap

This happens because the fuel gauge IC is still calibrated to the old cell's discharge curve. When the modem transmits or the screen draws peak current, the new cell's voltage drops faster than the IC expects — it reads 25% but the cell voltage is already at the protection floor. The BMS trips and the phone cuts off. One full discharge-charge cycle with fast charging disabled forces the coulomb counter to relearn the new cell's actual capacity, and the shutdowns stop.

Phone feels warm near the battery during the first charge after replacement

A new cell starts with higher internal impedance than a broken-in cell. During CC-phase charging, the charge IC pushes current into that higher resistance, and the extra energy dissipates as heat. This is normal for the first one or two cycles and reduces as impedance drops. If the phone stays warm past two full charge cycles, check that the charge IC is not stuck in a fast-charge mode — dropping to a standard 5V/1A charger for the break-in cycles keeps temperatures in range.