EP04XL Replacement Battery for HP Elite Dragonfly G1 7.7V 6800mAh

HP Elite Dragonfly G1 / G2 — 7.7V Li-Polymer Replacement Battery (EP04XL)

This is a 7.7V, 6800mAh (52.36Wh) lithium-polymer battery for the HP Elite Dragonfly G1, G2, Dragonfly Max, and Dragonfly-8MK79EA. It replaces OEM part EP04XL and cross-references HSTNN-DB9J, HSTNN-IB8Y, L52448-1C1, and L52581-005 among others. The cell slots into the same bay as the original and uses the same BMS handshake protocol.

• G1, G2, Max, and 8MK79EA compatibility: All four models share the same 7.7V battery rail, identical connector pinout, and the same BMS communication stack over SMBus. One cell fits all four without modification.
• Bench tested on actual hardware: We ran this cell through charge-discharge cycles on a G1 unit. The BMS handshake completed on first boot, state-of-charge reporting stabilised after three full cycles, and thermal cutoff thresholds behaved within spec under sustained CPU and display load.
• Post-install calibration for the Dragonfly: After fitting this cell, run one full discharge to 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 this platform.

Why the Elite Dragonfly shuts down at 20–30% after a battery swap

The Dragonfly's BIOS maps discharge curves against data stored from the previous cell. With a new cell installed, those stored curves no longer match the actual voltage-capacity relationship of the fresh chemistry. Under full CPU plus display load, the BIOS sees voltage drop faster than its model predicts and triggers a protective shutdown before the cell is actually depleted. Running two to three full discharge-recharge cycles lets the fuel gauge IC re-learn the new cell's curve, after which the reported percentage tracks accurately to cutoff.

BIOS reporting battery health as "poor" or "unknown" immediately after installation

HP's battery health check reads EEPROM data broadcast by the BMS — cycle count, rated Wh, and internal resistance — and compares it against expected values for the platform. A freshly installed cell starts with a cycle count of zero and EEPROM values that differ from the worn original, which the BIOS initially flags as an anomaly rather than a healthy cell. This is a firmware interpretation issue, not a fault with the battery. Boot into HP Support Assistant or run the built-in battery check after completing the calibration cycle; the health status should clear to normal once the BIOS has logged at least one full learn cycle at 100%.