About this replacement
Acer Aspire 3820T Series — 11.1V Li-ion Replacement Battery (AS10B31)
This 11.1V, 4400mAh (48.84Wh) Li-ion battery replaces the original cell in the Acer Aspire 3820T and its variants, including the 3820T-5246, 3820T-7459, and 3820T-332G16N. It also cross-references OEM part numbers AS10B41, AS10B7E, AS10B5E, AS10B61, AS10B6E, AS10B3E, AS10B51, and AS10E7E. Physical dimensions are 268.73 x 21.45 x 23.33mm — confirm your tray matches before fitting.
- Aspire 3820T platform fit: The 3820T family shares a common battery tray geometry, connector pinout, and BMS handshake across all sub-models in this series. Any unit carrying an AS10B-prefix OEM part number uses the same voltage rail and communication protocol, so one cell covers the full range.
- Bench tested on actual hardware: We cycled this cell through charge, full-load discharge, and sleep-state draw on a 3820T unit. The BMS reported correct voltage at each charge threshold, and the protection circuit tripped cleanly at the low-voltage cutoff without requiring a manual reset.
- BIOS learn cycle after installation: After fitting this cell, run one full discharge to hibernate cutoff, then charge uninterrupted to 100%. The 3820T BIOS uses this cycle to recalibrate its battery model against the new cell's actual capacity — skipping it leaves the health indicator stuck on the previous cell's data.
Why the Aspire 3820T BIOS flags a new battery as poor health immediately after swap
The 3820T stores battery health data in EEPROM on the original cell. When you fit a replacement, the BIOS reads that stored data and flags the new cell as degraded — because the EEPROM record belongs to the old cell, not the one now installed. This is a firmware behaviour, not a fault with the replacement cell. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the BIOS to rewrite the battery model against the new cell. After two to three cycles, the health indicator updates and the warning clears.
Laptop shuts down at 20–30% charge shown on screen
This happens when the fuel gauge IC's calibration is still mapped to the old cell's discharge curve. Under combined CPU and display load, the new cell's actual voltage drops faster than the gauge predicts, and the system hits the hardware cutoff before the percentage reaches zero. It is not a dead cell — it is a mismatch between the gauge's model and the new chemistry. Run two complete discharge cycles to hibernate cutoff, charging fully to 100% each time. After the second cycle, the fuel gauge IC recalibrates its curve and the shutdowns stop; confirm the cell holds above 10.5V under load before ruling out a deeper fault.