Motorola T180 Replacement Battery AANN4012A 3.6V 850mAh

Motorola T180 Series — 3.6V Ni-MH Replacement Battery (AANN4012A)

This is a 3.6V, 850mAh Ni-MH replacement battery for the Motorola T180, T180e, T182, and T300 mobile phones. It replaces the original AANN4012A cell when the existing battery no longer holds a usable charge. The cell matches the original voltage and physical dimensions, so it seats correctly in the battery compartment.

• T180, T180e, T182, and T300 compatibility: These four models share the same battery bay geometry, connector orientation, and 3.6V single-cell Ni-MH power rail. The AANN4012A form factor covers all four without modification.
• Bench tested on actual hardware: We cycled this cell through full discharge and recharge on a T180 unit. The phone accepted the cell without error, and the charge circuit completed a full cycle without interruption.
• Ni-MH first-cycle conditioning: Ni-MH cells are sensitive to partial charging early in their life. Run two full discharge-to-charge cycles before using the phone heavily — this prevents the memory effect from locking the cell into a shortened capacity range from day one.

Why the T180 reports the wrong battery percentage after a cell swap

The T180's fuel gauge is calibrated to the discharge curve of the original cell. A new Ni-MH cell has a slightly different voltage-versus-capacity profile, so the gauge reads inaccurately until it relearns. This shows up as the percentage jumping erratically or plateauing at an incorrect value. Run one full discharge from 100% down to automatic shutoff, then charge uninterrupted to 100% — the gauge recalibrates against the new cell's actual curve during that cycle.

Sudden shutdown at 15–25% battery remaining on the replacement cell

Ni-MH cells have a relatively flat discharge curve that drops steeply at end of life. Under load from a call or active screen, the cell voltage can cliff suddenly below the phone's minimum operating threshold — typically around 3.0V — even when the gauge still shows charge remaining. This is a fuel gauge calibration lag, not a faulty cell. A full discharge-recharge cycle resets the gauge reference point and eliminates most premature shutdowns.