About this replacement
HP ProBook 4340s / 4341s — 10.8V Li-ion Replacement Battery (668811-541)
This is a 10.8V, 4400mAh (47.52Wh) lithium-ion battery for the HP ProBook 4340s and ProBook 4341s laptops. It replaces OEM parts 668811-541, 668811-851, 669831-001, HSTNN-UB3K, HSTNN-W84C, RC06, RC06XL, H4Q46AA, and HSTNN-YB3K. Physical dimensions are 206.10 × 50.70 × 20.30mm — confirm these against your current cell before ordering.
- ProBook 4340s and 4341s compatibility: Both models run the same 10.8V power rail and use an identical connector and BMS handshake. HP used the same battery platform across both SKUs, so one cell covers both machines without any adapter or wiring change.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a ProBook 4340s unit. The BMS communicated correctly with the EC, charge current stepped down normally at 95%, and the fuel gauge tracked accurately across the full state-of-charge window.
- Post-install calibration on the ProBook 4340s: 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 on the first boot after any cell swap.
BIOS reporting poor battery health immediately after fitting a new cell
The HP ProBook BIOS reads health data from the battery's EEPROM registers on first contact. When a new cell arrives, those registers don't yet reflect actual cycle history on that specific machine, so the BIOS flags it as degraded. This is a data mismatch, not a fault with the cell itself. Running a full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the EC to rewrite those registers against real measured data. After one or two complete cycles, the BIOS health indicator should clear to normal.
Laptop shuts down abruptly at 20–30% charge shown on the gauge
This happens when the cell voltage drops below the EC's minimum threshold under combined CPU and display load before the fuel gauge reaches zero. It's a voltage cliff — the cell can't sustain the current draw at that state of charge, and the EC cuts power to protect the board. On the ProBook 4340s, this usually follows several incomplete calibration cycles that left the fuel gauge IC misaligned with the actual cell chemistry. Discharge the laptop fully to automatic hibernate, recharge to 100% without interruption, and repeat once more. The EC's fuel gauge IC recalibrates against the new cell and the cutoff point shifts back toward 0%.