About this replacement
Lenovo IdeaPad Duet 5 Chromebook 13Q7C6 — 7.72V Li-Polymer Replacement Battery (L21C4PG0)
This is a 7.72V, 5300mAh (40.92Wh) Li-Polymer replacement battery for the Lenovo IdeaPad Duet 5 Chromebook 13Q7C6 series. It replaces OEM part numbers L21C4PG0, L21D4PG0, L21L4PG0, L21M4PG0, and SB11D64647. It fits the 82QS regional variants sold across North America and Europe.
- 13Q7C6 series compatibility: All 82QS-prefix models share the same battery bay, connector pinout, and BMS communication protocol. The voltage rail and physical footprint — 242.60 × 93.80 × 3.50mm — are identical across regional variants, so one cell covers the full range.
- Bench tested on actual hardware: We ran this cell on a 13Q7C6 unit and confirmed the BMS handshake completes on first boot. The EC recognises the battery and begins the charge cycle without prompting any error state or unknown device flag.
- Post-install calibration on the 13Q7C6: After fitting this cell, run one full discharge until the device hibernates, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
Why the Duet 5 Chromebook shuts down at 20–30% after a battery swap
The fuel gauge IC on this platform maps voltage curves against the previous cell's EEPROM history. A new cell with no discharge history doesn't match those stored curves, so the gauge misjudges remaining capacity. Under combined CPU and display load, the new cell hits a voltage cliff that the IC interprets as empty — even when the gauge still shows 20–30%. Running two or three full discharge-to-hibernate and full charge cycles lets the IC rebuild an accurate curve against the replacement cell's actual chemistry.
BIOS reporting wrong Wh rating after installing a replacement cell
System information showing an incorrect Wh figure — typically the old cell's rated value — is an EEPROM read issue, not a cell defect. The embedded controller caches the previous battery's rated Wh and doesn't always flush that on first boot. Complete the calibration cycle described above, then cold boot with the battery below 5V. After the learn cycle completes, the BIOS should report 40.92Wh to match the cell's actual rating.