About this replacement
LG 15Z90N Series — 7.74V Li-Polymer Replacement Battery (EAC64618302)
This is a 7.74V, 8900mAh (68.89Wh) Li-Polymer replacement battery for the LG gram 15Z90N and related thin-and-light ultrabooks. It fits the 15Z90N, 15Z90P, 15Z990, 15ZT90P, and over a dozen additional gram variants that share the same battery bay and connector. The OEM part numbers are EAC64618302 and LBV7227E.
- 15Z90N and 15Z90P series compatibility: These gram models share the same low-profile battery bay, 7.74V two-cell Li-Polymer architecture, and connector pinout. The BMS handshake uses the same EEPROM communication protocol across the series, so the same cell works across all listed variants without modification.
- Bench tested on actual hardware: We ran this cell through charge, discharge, and BMS communication checks on a 15Z90N unit. The BMS accepted the cell, voltage regulation held steady across load transitions, and the protection circuit tripped correctly at both over-voltage and under-voltage thresholds.
- First-cycle calibration on the gram platform: After fitting this cell, run one full discharge down to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears on the gram platform after every cell swap.
Why the LG gram 15Z90N shuts down at 20–30% after a battery swap
The gram's fuel gauge IC stores charge-curve data calibrated to the original cell. A new cell with different internal resistance shifts the voltage-to-capacity curve, so the IC calls empty well before the cell actually is. Under full CPU and display load, the voltage sag is steeper, triggering an early shutdown that looks like a battery fault but is actually a calibration gap. Two to three full discharge-and-charge cycles give the fuel gauge IC enough data to recalibrate against the new cell's curve. After calibration, the reported percentage and actual cutoff voltage align.
BIOS reporting incorrect Wh rating after fitting a replacement cell
The Wh figure the BIOS displays comes from EEPROM data written to the battery's protection circuit, not from a live measurement. When the EEPROM-stored value doesn't match the actual cell chemistry, the BIOS reads the stored number and flags a mismatch or shows the wrong capacity entirely. This is a data discrepancy, not a fault with the cell. To clear it, enter the BIOS battery settings, run a full learn cycle, and confirm the reported value updates to match the installed cell's rated 68.89Wh.