T-Mobile Aspect Li3710T42P3h483757 Replacement Battery 3.7V

T-Mobile Aspect — 3.7V Li-ion Replacement Battery (Li3710T42P3h483757)

This is a 3.7V, 900mAh Li-ion battery that replaces the original cell in the T-Mobile Aspect candybar phone. It fits the Aspect directly using OEM part number Li3710T42P3h483757. Install it when the original battery no longer holds a charge or the phone refuses to power on.

• T-Mobile Aspect fit: The Aspect uses a single Li-ion cell at 3.7V nominal with a compact 47.67 × 37.27 × 5.80mm footprint. This replacement matches those dimensions and the OEM connector orientation so the BMS on the phone's charge IC can handshake correctly without fault codes.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a controlled load. The BMS held cutoff at the correct low-voltage threshold and the charge IC accepted a standard CC/CV charge profile without triggering a fault or dropping the connection mid-cycle.
• Fuel gauge recalibration on first use: After installing this cell, run one full discharge down to auto-shutoff, then charge uninterrupted to 100% before normal use. The Aspect's fuel gauge IC was calibrated to the original cell's discharge curve — one complete cycle resets that baseline against the new cell.

Sudden shutdown at 20–30% on the T-Mobile Aspect after a cell swap

This happens when the fuel gauge IC still references the old cell's voltage-to-capacity curve. A new cell can have a slightly steeper voltage drop under load at the lower end of its charge window. When the phone's modem transmits or the backlight fires, instantaneous current draw pulls the cell voltage below the BMS cutoff threshold even though the gauge still shows charge remaining. The fix is one full discharge-charge cycle, which forces the coulomb counter to remap against the new cell's actual discharge curve. After that cycle, shutoffs at 20–30% should stop.

T-Mobile Aspect shows incorrect battery percentage after replacement

The phone's fuel gauge IC stores a learned discharge model from the original cell. Drop in a new cell and that stored model no longer matches the actual charge state, so the percentage readout drifts — sometimes reading full when the cell is at 60%, or jumping several points between screen-on and screen-off states. This is not a fault with the replacement cell. Discharge the phone completely until it shuts itself off, then charge it to 100% in a single uninterrupted session. That cycle resets the coulomb counter and aligns the percentage display to the new cell's actual capacity curve.