About this replacement
HP EliteBook Folio G1 — 7.7V Li-Polymer Replacement Battery (EO04XL)
This is a 7.7V, 4600mAh (35.42Wh) Li-Polymer replacement battery for the HP EliteBook Folio G1 ultrabook. It fits all EliteBook Folio G1 variants, including the Subnotebook and specific SKUs such as 1EN92ES and V1C37EA. It replaces OEM part numbers EO04XL, 827927-1B1, 827927-1C1, 828226-005, HSTNN-I73C, and HSTNN-IB71.
- EliteBook Folio G1 platform fit: Every Folio G1 variant shares the same 7.7V power rail, flat Li-Polymer form factor, and BMS communication protocol. The connector pinout and physical dimensions — 269.70 × 120.20 × 5.70 mm — are identical across all listed SKUs, so no adapter or modification is needed.
- Bench tested on actual hardware: We cycled this cell through charge, idle draw, and sustained CPU load. The BMS correctly reported state-of-charge to the host system and held voltage within spec under combined display and processor load without triggering a protection cutoff.
- BIOS learn cycle after installation: After fitting this battery, run one full discharge to the hibernate cutoff, 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 the Folio G1.
BIOS reporting battery health as poor immediately after replacement
The Folio G1 BIOS reads health data stored in the old cell's EEPROM and compares it against the new cell's reported values. Because the EEPROM signature differs from what BIOS last recorded, it flags the battery as degraded or unknown — even when the cell is brand new. This is not a fault with the replacement cell. Run one complete discharge-to-hibernate then a full uninterrupted charge cycle, and the BIOS will recalibrate its health baseline against the new cell's data.
Folio G1 shutting down abruptly at 20–30% charge shown
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The gauge thinks 20–25% remaining maps to a safe voltage, but under combined CPU and display load the cell hits its lower voltage cliff faster than the old calibration expects. The BMS trips a protection cutoff before the OS can act, causing an instant shutdown rather than a graceful hibernate. Run two full discharge-to-hibernate and charge-to-100% cycles — after that, the fuel gauge IC recalibrates and shutdown will not occur until the cell genuinely reaches its low-voltage threshold.