Alcatel T790Y Replacement Battery TLP043E7 3.85V 4250mAh

Alcatel T790Y Series — 3.85V Li-Polymer Replacement Battery (TLP043E7)

This is a 3.85V, 4250mAh Li-Polymer battery for the Alcatel T790Y, T790H, T790S, and T790W smartphones. It replaces the OEM cell TLP043E7 (also listed as TLp043E1) when the original no longer holds charge or has swollen. Dimensions are 78.54 × 63.00 × 4.95mm — measure your existing cell before fitting.

• T790 series compatibility: The T790Y, T790H, T790S, and T790W share the same battery bay dimensions, connector pinout, and BMS handshake protocol — all use the TLP043E7 footprint with a matched 3.85V nominal rail.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on T790 series hardware. The BMS accepted charge current without fault flags, and the protection circuit triggered correctly at low-voltage cutoff.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard current. This lets the fuel gauge IC map the new cell's discharge curve before the OS uses that data for percentage reporting.

Sudden shutdown at 20–30% on the T790Y after a cell swap

A new Li-Polymer cell has a slightly different voltage-versus-capacity curve than the aged cell it replaces. The fuel gauge IC on the T790Y is still calibrated to the old, degraded curve. When the phone hits a voltage point the IC associates with "nearly empty," it shuts down — even if the new cell still has usable charge. The fix is one full discharge-charge cycle without fast charging, which forces the coulomb counter to re-learn the cell endpoints. After that cycle, shutdowns below 30% typically stop.

USB fast charge not activating on the first cycle after replacement

On the first charge after fitting a new cell, the T790Y's charge IC may fall back to standard 5V charging rather than negotiating a higher voltage. This happens because the BMS on a new, uncalibrated cell can present an unusual impedance signature that causes the handshake to fail. Plug into a standard 5V charger for the first full cycle, then switch back to your fast charger on the second charge. Most users see fast charging resume normally from cycle two onward.