Asus C11P1323 PadFone S Replacement Battery 3.8V 4900mAh

Asus PadFone S / PF500K — 3.8V Li-Polymer Replacement Battery (C11P1323)

This is a 3.8V, 4900mAh Li-Polymer cell built to fit the Asus PadFone S (PF500K, P93L, P92L). It replaces OEM part C11P1323 and secondary reference 0B200-00810000. Capacity figures come from our product data — 18.62Wh total energy at rated voltage.

• PadFone S variant coverage: The PF500K, P93L, and P92L share the same physical cell envelope (123.70 × 62.00 × 4.50 mm), connector pinout, and BMS handshake protocol — so one cell covers all listed variants without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the PadFone S platform. The BMS accepted the new cell without error flags, and the charge IC completed a full CC-CV cycle to 4.35V as expected.
• First-cycle fuel gauge reset: After fitting this cell, disable fast charging and run one complete discharge down to auto-shutoff, then charge to 100% on standard current. The fuel gauge IC on the PadFone S calibrates its coulomb counter against the new cell's discharge curve during that first cycle — skipping it leaves the percentage readout inaccurate for weeks.

Sudden shutdown at 20–30% on the PadFone S after a cell swap

A new Li-Polymer cell has a slightly different internal resistance profile than the aged cell it replaces. The PadFone S modem radio and display draw brief high-current spikes that can pull cell voltage below the BMS cutoff threshold — even when the fuel gauge still reads 25%. This is a voltage cliff event, not a capacity fault. It resolves after 2–3 full discharge-charge cycles as the fuel gauge IC maps the new cell's actual voltage-versus-capacity curve and adjusts the shutdown trigger point accordingly.

Phone warm near the battery during the first few charges after replacement

A fresh high-capacity Li-Polymer cell starts with higher impedance than a broken-in one. The charge IC on the PadFone S pushes constant current into that higher-impedance cell, and the resistance converts some of that energy to heat. This is expected behaviour for the first three to five cycles — not a fault with the cell or the charge circuit. If the back panel stays noticeably warm beyond five full cycles, check that the replacement cell's thickness matches the 4.50 mm spec, as an oversized cell pressed against the chassis traps heat against the charge IC.