Agilent N9340B Spectrum Analyzer Replacement Battery 10.8V 5200mAh

Agilent N9340B / N9330A Series — 10.8V Li-ion Replacement Battery (3CGR18650D-2)

This 10.8V 5200mAh Li-ion battery pack replaces the original power cell in the Agilent N9340B handheld spectrum analyzer and related N9330 series instruments. It also fits the N9330A, N9330, and N9334 among other compatible units. Voltage and capacity match OEM specifications exactly — confirmed against Part No 3CGR18650D-2, N9330B-BCG, and N9330B-BAT.

• N9330 and N9340 series compatibility: These instruments share a common battery bay geometry, connector pinout, and BMS handshake protocol across the N9330, N9330A, N9340B, and N9334 platforms — which is why a single cell spec covers the entire range.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on N9340B hardware. The BMS completed its authentication handshake without fault, and the charge IC accepted the full 5200mAh input across both the first and second cycles.
• Post-swap startup protocol: After installing this battery, let the N9340B complete its full power-on self-test without interruption. The analyzer runs a BMS verification sequence at boot — cutting power mid-cycle writes a false battery fault to memory that persists until the next clean reboot.

Why the N9340B reports a battery fault after a fresh swap

The N9340B runs a BMS learn cycle during its first few charge-discharge passes on a new cell. Until that cycle completes, the analyzer's charge controller applies conservative thresholds calibrated to aged OEM chemistry — not a fresh cell. This mismatch causes the instrument to flag capacity or voltage readings that are actually normal for a new pack. Running one full charge-discharge cycle before field use lets the BMS recalibrate its state-of-charge model to the new cell's actual characteristics.

Charge indicator stalls below 100% on first charge

On the first charge after installation, the N9340B's charge IC applies a reduced current ceiling to an unrecognised cell — this is intentional behaviour, not a fault with the battery. The indicator commonly stalls between 85% and 95% and may show a flashing charge status rather than a solid full-charge icon. This resolves after the first complete cycle. Allow the battery to discharge to the low-battery warning — around 9.6V under load — then charge uninterrupted to completion before using the instrument in the field.