Keysight U1610A 10.8V Replacement Battery NF2040XD 5200mAh

Keysight U1610A / U1620A — 10.8V Li-ion Replacement Battery (NF2040XD)

This 10.8V Li-ion battery replaces the OEM NF2040XD pack in the Keysight U1610A and U1620A digital multimeters. Capacity is 5200mAh (56.16Wh). Both instruments share the same battery bay, connector pinout, and BMS communication protocol, so one part covers both models.

• U1610A and U1620A compatibility: Both meters run the same 10.8V three-cell Li-ion architecture with identical BMS handshake requirements. The pack must respond to the instrument's state-of-charge polling or the meter flags a battery fault and limits operation.
• Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on U1610A hardware. The BMS handled probe initialisation current spikes cleanly and maintained output voltage within the instrument's operating window throughout sustained measurement loads.
• Calibration cycle before first field use: After installing this pack, run a full calibration sequence through the instrument's menu before taking it to site. The U1610A maps battery state during calibration — skipping this step causes the low-battery indicator to trigger early during the first measurement session, even with a fully charged pack.

BMS lockout after the U1610A sat unused in a carry case for months

Li-ion cells self-discharge over time. If the pack drops below approximately 2.5V per cell during storage, the BMS trips into deep-discharge protection and the instrument will not respond to a normal charge cycle — the charger sees too low a voltage and refuses to engage. Recovery requires a compatible charger with a pre-charge or trickle-charge mode that can bring cell voltage up to around 3.0V per cell before the BMS releases the lockout. Once voltage recovers past that threshold, a standard charge cycle completes normally and cell balance restores.

Readings drifting or logging session resetting mid-capture

Sustained sensor loads during a logging session draw more current than single-point measurements. If the pack has aged or cells are unbalanced, voltage sags under that continuous draw and the instrument's internal regulator drops out briefly — enough to interrupt the logging buffer and reset the session. The symptom looks like a software glitch but traces back to pack voltage dropping below the regulator's hold-up threshold. Check pack voltage under load with a second meter; a healthy pack should hold above 10.0V during active logging. Replace the pack if voltage falls below that under load.