Asus ZenFone Pegasus 4A C11P1610 Compatible Battery 3.85V

Asus ZenFone Pegasus 4A / ZB500TL — 3.85V Li-Polymer Replacement Battery (C11P1610)

This is a 3.85V, 4050mAh (15.59Wh) Li-Polymer cell for the Asus ZenFone Pegasus 4A and ZB500TL smartphones. It replaces OEM part C11P1610 (1ICP5/62/74) and fits the same physical bay with the same connector orientation. Use this when the original cell no longer holds a charge, swells, or causes unexpected shutdowns.

• ZenFone Pegasus 4A and ZB500TL compatibility: Both models run the same 3.85V battery rail, share the same connector pinout, and use the same BMS handshake protocol — one cell covers both variants without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on ZB500TL hardware. The BMS accepted charge from cold, balanced cells correctly under screen-on load, and held voltage above the shutdown threshold throughout the discharge curve.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-charge cycle at standard current. This lets the fuel gauge IC map the new cell's discharge curve before fast charge pushes higher current into an uncalibrated cell — skipping this step causes the percentage readout to drift or jump.

Sudden shutdown at 20–30% on the ZenFone Pegasus 4A after a cell swap

A new Li-Polymer cell has a slightly different voltage-to-capacity curve than the degraded cell the fuel gauge IC was calibrated against. When the phone hits a load spike — modem transmit, screen wake, or GPS — the cell voltage drops briefly below the shutdown threshold even though the displayed percentage reads 20–30%. The phone interprets this as a critical undervoltage event and cuts power instantly. One full discharge-charge cycle at standard current gives the coulomb counter enough data to remap the curve and move the shutdown trigger to the correct voltage.

USB fast charge not activating on the first cycle after replacement

After a cell swap, the charge IC on the ZB500TL sometimes defaults to trickle or standard 5V charging on the first cycle — it does not immediately negotiate the fast-charge protocol with a new, uncalibrated BMS. This is normal behaviour and not a fault with the replacement cell. Complete one full standard-current cycle first. On the second charge, fast charging should re-engage; if it does not, check that the charger output is at least 5V/2A and the cable supports data lines.