About this replacement
Acer Chromebook C738T / CB3-131 / CB5-132T — 10.8V Li-ion Replacement Battery (AC15A3J)
This is a 10.8V, 3450mAh (37.26Wh) Li-ion replacement battery for the Acer Chromebook C738T and related models including the CB3-131 and CB5-132T. It replaces OEM part numbers AC15A3J, KT.00303.017, AC15A8J, and KT.00305.004 among others. Fits the convertible 2-in-1 Chromebook platform used widely in education environments.
- C738T, CB3-131, CB5-132T fit group: These models share the same 10.8V three-cell Li-ion architecture, physical connector, and BMS handshake protocol. The AC15A3J part number spans the full CB-series range because Acer kept the same battery bay and charge controller across these SKUs.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a CB3-131 unit. The BMS accepted the connection without fault codes, the charge controller stepped through CC and CV phases cleanly, and the cell reached full rated voltage before the controller dropped to trickle.
- Post-install calibration on ChromeOS: After fitting this battery, run the charge down to automatic hibernate cutoff — do not force shutdown. Then plug in and charge uninterrupted to 100%. ChromeOS uses this cycle to reset the fuel gauge IC against the new cell's actual capacity curve, clearing the inaccurate health warning that appears after every cell swap.
ChromeOS reporting battery health as "poor" immediately after replacement
ChromeOS reads battery health from EEPROM data stored on the fuel gauge IC. When you swap a cell, the IC still holds the wear history and cycle count from the old battery. The OS interprets this stale data as a degraded cell and flags it as poor health — even on a brand-new replacement. Running one full discharge-to-hibernate followed by an uninterrupted full charge forces the fuel gauge IC to recalibrate against the new cell's actual voltage curve. After that cycle, the health indicator updates to reflect the real state of the new battery.
C738T shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC hasn't been calibrated to the replacement cell yet. The displayed percentage is based on the old cell's voltage-to-capacity map, so 25% on screen may already be below the actual low-voltage cutoff threshold for the new cell. Under full CPU and display load, the voltage drops sharply and the BMS trips before the OS can initiate a clean shutdown. Complete one full discharge-to-hibernate cycle and charge back to 100% without interruption — after recalibration the gauge will track accurately and the cutoff will align with the correct voltage floor of approximately 9.0V.