Asus Zenfone Max C11P1508 Replacement Battery 3.8V 5000mAh

Asus Zenfone Max ZC550KL — 3.8V Li-Polymer Replacement Battery (C11P1508)

This is a 3.8V, 5000mAh Li-Polymer cell for the Asus Zenfone Max, covering ZC550KL, Z010D, and Z010AD variants. It replaces OEM part C11P1508 directly on the logic board connector. Capacity figures come from the product data, not third-party sources.

• ZC550KL / Z010D / Z010AD platform fit: These variants share the same 3.8V battery rail, physical footprint, and flex connector pinout. The BMS handshake on each model reads cell voltage and temperature from the same two-wire interface, so the replacement cell communicates without modification.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a ZC550KL unit. The BMS accepted the cell on first connection, charge current ramped normally through CC to CV phase, and no fault codes were logged in the battery stats partition.
• Fuel gauge recalibration on first install: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC build an accurate discharge curve for the new cell before high-current charging pushes current into an uncalibrated state register.

Why the Zenfone Max reports wrong battery percentage after a cell swap

The Zenfone Max uses a coulomb-counter fuel gauge IC that stores learned discharge curve data from the original cell. When a new cell goes in, the IC still references the old curve, so percentage readings drift — often showing full charge or dropping suddenly. The fix is one full uninterrupted discharge down to automatic shutdown, followed by a full charge to 100% without interruption. After that single cycle, the IC resets its reference points against the actual cell behaviour.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC has not yet mapped the new cell's voltage cliff — the point where cell voltage collapses rapidly under modem or display load. The phone cuts power to protect the cell before the percentage display catches up. It is not a faulty cell; it is an uncalibrated gauge. Run two full discharge-to-shutdown and full-recharge cycles, and the IC learns where the real low-voltage threshold sits. After calibration, shutdown should not occur above approximately 3.4V per cell.