AT&T 8900 Replacement Battery KAS160 3.7V 1100mAh

AT&T 8900 / 8925 Tilt Series — 3.7V Li-Polymer Replacement Battery (KAS160)

This is a 3.7V, 1100mAh (4.07Wh) lithium-polymer cell for the AT&T 8900 and 8925 Tilt smartphones. It replaces OEM part numbers KAS160, KAIS160, 35H00088-00M, and 35H00086-00M. If the original cell no longer holds a charge, this swap restores normal device operation without replacing the phone.

• 8900 and 8925 Tilt compatibility: Both models run on the same 3.7V cell with identical connector orientation and BMS handshake protocol. The shared platform means one cell covers the full Tilt family, including the slide-keyboard 8925 variant.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the 8900 platform. The BMS communicated correctly with the charge IC, and the fuel gauge IC registered the cell without error codes or charge interruption.
• Fuel gauge recalibration on first use: After installing this cell, disable fast charging if available and run one complete discharge down to auto-shutoff, then charge uninterrupted to 100%. This gives the fuel gauge IC one full reference cycle against the new cell's actual discharge curve before normal use.

Why the AT&T 8900 reports wrong battery percentage after a cell swap

The 8900 uses a fuel gauge IC that stores a learned discharge curve from the original cell. When you install a new cell, that stored curve no longer matches the actual electrochemistry of the replacement. The gauge reads voltage and maps it against the old curve, producing percentage values that are off — sometimes by 15–20 points. Running one full discharge-to-shutoff cycle followed by an uninterrupted charge to 100% forces the IC to rewrite its reference map against the new cell. After that single cycle, percentage accuracy returns to normal.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC hasn't recalibrated and the cell hits a voltage cliff the old map didn't predict. Under modem or screen load, the cell voltage drops faster than the gauge expects, and the phone cuts power before the displayed percentage reaches zero. The fix is the same recalibration cycle — one full discharge to auto-shutoff, then a full uninterrupted charge. If the shutdowns continue after two full cycles, check that the battery connector is fully seated; a partial connection raises internal resistance and accelerates voltage sag under load.