About this replacement
Acer Chromebook Spin 311 CP311-3H-K2RJ — 7.5V Li-Polymer Replacement Battery (AP16L8J)
This is a 7.5V, 4800mAh (36Wh) Li-Polymer battery for the Acer Chromebook Spin 311 CP311-3H-K2RJ convertible laptop. It also fits the CP311-3H and Spin 513 CP513-1H and CP513-1HL series. Part numbers AP16L8J, KT.0020G.010, KT.00205.008, KT.00205.002, and AP16L5J all cross to this cell.
- Spin 311 and Spin 513 shared platform: Both series run the same 7.5V two-cell Li-Polymer architecture with a matching connector pinout and BMS handshake protocol — that is why one SKU covers both lines. Swap one and the firmware reads the cell correctly without additional configuration.
- Bench tested on actual hardware: We ran this cell through the Spin 311 charge controller and confirmed the BMS negotiated full charge acceptance at 8.7V cutoff. No false full-charge flags and no thermal events during the charge cycle.
- First cycle after installation: After fitting this cell, run the Chromebook down to automatic hibernate-cutoff under normal screen and CPU load, then charge uninterrupted to 100%. This forces the battery learn cycle to reset, which clears the inaccurate health warning that appears in ChromeOS after any cell swap.
Why ChromeOS reports poor battery health immediately after a cell swap
The Chromebook's embedded controller stores charge history and health metrics in EEPROM tied to the old cell. When a new cell goes in, the controller reads stale data and flags health as poor or unknown before any cycles have run. This is not a fault with the replacement cell. One full discharge-to-hibernate followed by an uninterrupted charge to 100% triggers the battery learn cycle, which writes fresh baseline data to the controller and clears the warning.
Spin 311 shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The IC is still using the old cell's discharge profile, so it calls a low-voltage shutdown earlier than the real cutoff. It is not a defective cell. Run two to three full discharge-to-hibernate and full-charge cycles and the fuel gauge re-maps itself against the new chemistry — shutdowns will stop occurring above 4.0V per cell.