About this replacement
Asus ZenFone 2 / ZE500CL / ZE551KL — 3.7V Li-Polymer Replacement Battery (C11P1501)
This 3.7V, 2500mAh Li-Polymer cell replaces the original C11P1501 battery in the Asus ZenFone 2 lineup. It fits the standard ZenFone 2, ZenFone 2 Dual SIM, ZE500CL, ZenFone 2 Laser ZE551KL, and 13 additional ZenFone 2 variants. Dimensions are 81.20 × 53.10 × 4.80mm — match these before installation if your model isn't listed.
- ZenFone 2 platform fit: The ZenFone 2 series shares the C11P1501 footprint and connector across multiple sub-models despite name differences. Voltage rail and BMS handshake are consistent across ZE500CL and ZE551KL variants, so one cell covers the full range.
- Bench tested on actual hardware: We cycled this cell on a ZE551KL unit and logged BMS charge acceptance through three full cycles. Charge current stabilised correctly on the second cycle, and the protection circuit tripped as expected at the low-voltage cutoff threshold without locking out the board.
- Fuel gauge recalibration after cell swap: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the ZenFone 2's fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging pushes current into an uncalibrated state.
Sudden shutdown at 20–30% on the ZenFone 2 after a cell swap
The ZenFone 2 shuts down abruptly at 20–30% because the fuel gauge IC is still reading the old cell's discharge curve. The new cell's voltage drops faster under modem or display load than the calibration table expects, so the board sees a voltage cliff and cuts power before the percentage reaches zero. This is not a fault with the replacement cell — it resolves after one complete discharge to below 5% and a full charge to 100% without interruption. After that cycle, the coulomb counter resets against the actual cell behaviour and shutdowns stop.
ZenFone 2 not powering on after the battery was stored or left discharged
A Li-Polymer cell left discharged in storage can drop below 2.5V per cell, triggering a BMS lockout that blocks normal charging. The phone shows no charge indicator and appears completely dead. Connect the device to a wall charger — not a PC USB port — and leave it for 20–30 minutes without attempting to power it on. If the cell hasn't dropped below the hard cutoff floor, the charge IC will trickle current into the cell until voltage recovers above 3.0V and the BMS re-enables normal charge current.