AMOI N89 Replacement Battery 3.7V 1300mAh O13

AMOI N89 / N816 Series — 3.7V Li-ion Replacement Battery (O13)

This is a 3.7V, 1300mAh Li-ion replacement battery for the AMOI N89, N806, N807, and N816 mobile phones. It replaces the original O13 cell when capacity has dropped and the phone no longer holds a useful charge. Capacity figure is 4.81Wh at nominal voltage.

• N89, N806, N807, N816 compatibility: These four models share the same O13 cell format — identical footprint (51.77 × 50.95 × 4.95mm), same 3.7V nominal rail, and the same connector orientation. Swapping between them requires no adapter or modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS held charge termination correctly at 4.2V and did not trigger overcurrent cutoff during normal screen-on load draws. Protection circuitry responded as expected to simulated short conditions.
• Fuel gauge recalibration on first install: After fitting this cell, run one complete discharge down to auto-shutdown, then charge to 100% before resuming normal use. The phone's fuel gauge IC was calibrated against the original cell's discharge curve — one full cycle resets that reference against the new cell, preventing erratic percentage readings early on.

Why the N89 reports the wrong battery percentage after a cell swap

The N89 uses a fuel gauge IC that tracks charge state by mapping voltage against a stored discharge curve from the original cell. A new Li-ion cell has slightly different impedance and a steeper voltage curve at low states of charge compared to an aged cell. Until the IC recalibrates, it reads percentage from the wrong curve — so the display can show 40% while the actual cell voltage is already near cutoff. One full discharge-to-shutdown followed by an uninterrupted charge to 100% gives the IC enough data to rebuild an accurate curve map. After that cycle, percentage readings stabilise.

Phone shuts off suddenly at 20–30% on the replacement cell

This is a voltage cliff issue, not a capacity problem. When the screen backlight and radio draw current simultaneously, internal cell resistance causes a sharp voltage drop — and if the fuel gauge IC still holds the old cell's curve, it allows discharge deeper than the BMS will tolerate. The BMS then cuts output to protect the cell, which the phone reads as a sudden power loss. The fix is the same recalibration cycle: discharge fully to auto-shutdown, then charge to 4.2V (100%) in one uninterrupted session. After one complete cycle, the fuel gauge IC tracks the new cell accurately and stops permitting load draw into the cutoff zone.