About this replacement
HP EliteBook 820 Series — 11.1V Li-Polymer Replacement Battery (SB03XL)
This 11.1V, 4140mAh (45.95Wh) lithium-polymer cell replaces the original battery in the HP EliteBook 820, 820 G1, and 820 G2 series notebooks. It matches the OEM voltage rail and connector spec for direct fitment. Part numbers SB03XL, HSTNN-LB4T, and 717378-001 are all covered by this cell.
- EliteBook 820 / 820 G1 / 820 G2 fitment: All three generations share the same 11.1V battery bay, connector pinout, and BMS communication protocol over SMBus. The charge controller in each model reads the same EEPROM identifiers, so the cell handshakes without firmware conflict.
- Bench tested on actual hardware: We ran this cell on an EliteBook 820 G1 and 820 G2 unit. The BMS accepted the cell immediately, charge current ramped normally through CC/CV stages, and the fuel gauge IC registered capacity without triggering an unknown-battery error.
- Post-swap calibration cycle: After installing, run the laptop down to hibernate-cutoff under normal load — screen on, Wi-Fi active — then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell and clears the inaccurate health warning that appears on first boot after every cell swap.
BIOS reporting battery health as poor immediately after replacement
The EliteBook 820 BIOS stores learned capacity data from the previous cell in its battery learn table. When a new cell goes in, the BIOS compares live readings against stale data and flags a health warning — not a fault with the new cell. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the BIOS to rewrite the learn table against the new cell's actual chemistry. After one or two of these cycles the health status clears. If the warning persists past three full cycles, check BIOS version — some early 820 G1 firmware builds require an update before the learn cycle resets correctly.
EliteBook 820 shutting down at 20–30% charge shown on the gauge
This happens when the fuel gauge IC has not yet calibrated against the new cell's discharge curve. The IC still uses the old cell's voltage-to-capacity map, so it misreads the new cell's voltage cliff and triggers a shutdown well before actual depletion. It is not a defective cell — the map just needs a reset. Run two full discharge-to-hibernate cycles with the display at full brightness and a CPU load running, then charge each time to 100%. By the second or third cycle the gauge IC recalibrates and the early-shutdown stops. The target resting voltage at full charge should read between 12.4V and 12.6V on a calibrated cell.