About this replacement
Acer Chromebook Spin 11 CP311-1HN-C3E3 — 11.55V Li-Polymer Replacement Battery (AP19A8K)
This is an 11.55V, 3450mAh (39.85Wh) Li-Polymer battery cell for the Acer Chromebook Spin 11 and CP311 series convertibles. It replaces part number AP19A8K — the original internal cell that powers these 11-inch 2-in-1 Chromebooks. When the original cell degrades and the device can no longer hold a usable charge, this swap restores unplugged operation.
- CP311 series compatibility: The CP311-1HN, CP311-2HN, CP311-3H, and related variants share the same AP19A8K cell format, voltage rail, and BMS connector. The battery management handshake is identical across the lineup, so one part number covers all listed models.
- Bench tested on actual hardware: We cycled this cell on CP311 hardware and confirmed the BMS completed full charge termination at 11.55V, with no false low-voltage cutoffs and accurate state-of-charge signalling to ChromeOS from the first cycle.
- Post-swap calibration on the CP311: After installing, run the Chromebook down to automatic hibernate-cutoff, then charge uninterrupted to 100% without using the device. This resets the fuel gauge IC's learn cycle and clears the inaccurate battery health warning that ChromeOS displays after every cell replacement.
ChromeOS reporting poor battery health immediately after AP19A8K swap
The Acer EC firmware reads EEPROM data from the outgoing cell and stores a health baseline. When a new cell goes in, the EC compares current readings against that stale baseline and flags health as poor or degraded before the new cell has run a single cycle. This is a firmware artefact, not a sign of a faulty replacement. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the EC to rewrite the health register against the new cell's actual capacity curve. After that cycle, the health indicator resets to normal.
CP311 shutting down at 20–30% charge shown on screen
This happens when the cell voltage drops below the BMS cutoff threshold under combined CPU and display load, even though the fuel gauge still reads 20–30%. The fuel gauge IC has not yet mapped the new cell's voltage-to-capacity curve accurately — it is extrapolating from old data. The cell hits a voltage cliff under load before the gauge catches up. Run two or three full discharge-to-hibernate and full charge cycles; the fuel gauge IC recalibrates its curve against the new cell, and the premature shutdown stops. Confirm the gauge is reading correctly when resting voltage at 30% shown stays above 10.8V.