Alltel AS855 Compatible Battery 3.7V 1200mAh Li-ion

Alltel AS855 Ignite — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1200mAh Li-ion battery for the Alltel AS855 and Ignite smartphones. It replaces the original cell when the phone no longer holds a charge or shuts down unexpectedly. Capacity is 4.44Wh — matched to the original spec.

• AS855 and Ignite compatibility: Both devices share the same 3.7V single-cell architecture, physical footprint (64.50 × 44.40 × 4.50mm), and connector layout. The BMS handshake is identical across both models, so one cell fits either device without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a smartphone test rig. The BMS held cutoff cleanly at the low-voltage threshold and accepted charge current without triggering protection interrupts on either the AS855 or Ignite platform.
• Fuel gauge recalibration on first use: On first installation, disable fast charging and run one complete discharge-to-charge cycle at standard current. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state — preventing erratic percentage readings from day one.

Sudden shutdown at 20–30% on the AS855 after a cell swap

The AS855 fuel gauge IC retains the discharge curve of the old cell in memory. When a new cell is installed, the IC mispredicts the voltage cliff — the point where cell voltage drops sharply under modem or screen load. The phone reads 25% remaining, but the actual cell voltage has already sagged below the shutdown threshold under load. One full discharge cycle from 100% to automatic cutoff, followed by a full charge without interruption, forces the coulomb counter to re-anchor to the new cell's actual curve. After that cycle, shutdowns at false-high percentages stop.

Phone feels warm near the battery during the first few charges

A new Li-ion cell has slightly higher internal impedance than a broken-in cell. The charge IC on the AS855 pushes the same current profile it used on the original cell, and the higher impedance converts more of that energy to heat during the first few cycles. This is normal and tapers off after two or three full charge cycles as the cell's internal resistance settles. If warmth persists beyond the third cycle or the phone becomes hot to the touch, check that the charge port is clean and that no third-party fast-charge adapter is connected — revert to the stock charger and confirm charge current drops to the standard 5V/1A input.