About this replacement
HP EliteBook 840 G5 Series — 11.55V Li-ion Replacement Battery (SS03XL)
This 11.55V, 4250mAh (49.09Wh) lithium-ion battery replaces the original cell in the HP EliteBook 840 G5. It fits the 840 G5 across multiple SKUs including 3JX43EA, 3ZG47ES, 3TU08PA, and 3UW57PC. OEM part numbers covered include SS03XL, HSTNN-IB8C, HSTNN-DB8J, and 932823-171 among others.
- 840 G5 multi-SKU coverage: HP shipped the 840 G5 in dozens of regional and channel variants — 3JX43EA, 3ZG47ES, 3UW57PC, and 3TU08PA among them — but all share the same battery bay geometry, 11.55V three-cell architecture, and SS03XL connector and BMS handshake protocol. One cell covers the full lineup.
- Bench tested on actual hardware: We ran this cell through charge-discharge cycles on an 840 G5 chassis. The BMS negotiated correctly with the EC controller, charge current ramped as expected through CC and CV phases, and the fuel gauge IC registered capacity without triggering a fault flag.
- Post-install calibration on the 840 G5: After fitting this cell, run the laptop on battery until it hibernates at cutoff, then charge uninterrupted to 100% without interruption. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears on the first boot after any cell swap.
BIOS reporting battery health as poor after fitting the new cell
The HP BIOS on the 840 G5 reads health data from the battery's EEPROM and compares it against charge history logged on the old cell. A fresh cell has no cycle history, so the BIOS interprets this mismatch as degradation and flags poor health or an unknown battery warning. This is a firmware calibration issue, not a fault with the replacement cell. Run one complete discharge-to-hibernate cycle followed by a full uninterrupted charge to 100%. After that single learn cycle, the BIOS re-evaluates and the health warning clears.
Laptop shuts down at 20–30% charge shown on screen
This happens when the fuel gauge IC still holds calibration data from the old, degraded cell. The IC predicts shutdown voltage based on the old cell's discharge curve, which no longer matches the new chemistry. Under combined CPU and display load, the laptop hits the predicted voltage cliff before the gauge reaches 0%, triggering an immediate shutdown. Running two full discharge-to-hibernate cycles recalibrates the IC against the new cell's actual discharge curve. After calibration, the gauge tracks accurately and the early shutdowns stop. Target a resting voltage of around 11.1V at the hibernate cutoff point to confirm the IC is reading the new cell correctly.