Asus Zenfone 3 Max 5.5 Replacement Battery 3.85V 3400mAh

Asus Zenfone 3 Max 5.5 — 3.85V Li-Polymer Replacement Battery (C11P1609)

This is a 3400mAh Li-Polymer cell replacement for the Asus Zenfone 3 Max 5.5. It fits the ZC553KL, ZenFone 3 Max Dual SIM 5.5, and X00DDA variants. Voltage is 3.85V and energy output is 13.09Wh — pulled directly from product data, not estimated.

• ZC553KL and X00DDA platform fit: These variants share the same connector pinout, BMS handshake protocol, and 3.85V voltage rail. One cell part number — C11P1609 — covers all of them because the charge IC and fuel gauge IC are identical across the board.
• Bench tested on actual hardware: We cycled this cell through a full discharge-charge sequence on a ZC553KL unit. The BMS accepted the handshake without error flags, and the charge IC ramped to the correct constant-current phase without thermal cutoff triggering.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge down to auto-shutoff, then charge to 100% uninterrupted. This gives the coulomb counter a clean reference curve against the new cell before the charge IC starts pushing higher current loads.

Sudden shutdown at 20–30% on the Zenfone 3 Max 5.5

This is a voltage cliff failure. The cell cannot hold its voltage above the BMS cutoff threshold when the modem, GPS, or screen pulls a current spike — even though the fuel gauge still reads 20–30%. The old cell's discharge curve is flatter and drops off a cliff under load well before the percentage suggests it should. A replacement cell with a fresh discharge curve eliminates the sag point that triggers the cutoff. After swapping, run one full calibration cycle so the fuel gauge IC maps the new curve correctly.

Phone reports wrong battery percentage after cell swap

The fuel gauge IC on the ZC553KL uses a coulomb counter calibrated to the original cell's capacity and discharge curve. When a new cell goes in, that stored curve no longer matches actual cell behaviour, so the percentage readout drifts — often jumping erratically or showing 100% that drops to 80% within minutes. The fix is one full uninterrupted cycle: drain to automatic shutoff, then charge to 100% without interruption. That single cycle resets the coulomb counter reference and brings the percentage display back into alignment.