Fluke LIQ-100 Compatible Battery 3.7V 5200mAh Li-ion

Fluke LIQ-100 / LinkIQ Series — 3.7V Li-ion Replacement Battery (FNBP-LION-01)

This is a 3.7V 5200mAh Li-ion replacement for the Fluke LIQ-100 liquid analyzer and LinkIQ series field instruments. It fits the LIQ-100, LIQ-100-IE, and Networks LIQ-100-IE variants that all run on the FNBP-LION-01 cell pack. Swap it in when the original pack no longer holds charge through a full field session.

• LIQ-100 and LinkIQ platform compatibility: The LIQ-100 family shares a common voltage rail, connector pinout, and BMS handshake across variants. Any model calling for FNBP-LION-01 draws from the same 3.7V cell configuration, so one pack covers the full lineup without firmware or connector issues.
• Bench tested on actual hardware: We cycled this pack through probe initialisation and sustained sensor logging. The BMS held steady through the current spike at probe power-up and did not trip under continuous measurement load at 3.7V nominal.
• First-install calibration cycle: After fitting the new pack, run a full calibration cycle through the instrument menu before going into the field. The LIQ-100 maps battery state during calibration — skip this and the instrument will throw premature low-battery warnings within the first measurement session.

LIQ-100 shutting down mid-measurement with the charge indicator still showing bars

The LIQ-100 pulls a short current spike each time it activates the probe module or switches measurement modes. On a degraded cell, internal resistance has risen enough that this spike causes a brief voltage sag below the BMS cutoff threshold — even when the indicator still reads partial charge. The instrument reads voltage, not true capacity, so it shows bars right up until the BMS trips. A fresh 5200mAh pack with low internal resistance handles the spike without the sag that triggers shutdown.

Pack will not charge and instrument shows no power after months in storage

Li-ion cells self-discharge during storage. If the pack has sat unused long enough, cell voltage drops below the BMS recovery threshold — typically under 2.5V per cell — and the protection circuit locks out charging entirely. The instrument shows nothing because there is not enough voltage to wake the BMS. To recover, apply a trickle charge via a bench charger or compatible Li-ion charger at around 0.1C for 15–30 minutes to bring cell voltage back above 2.8V, then switch to the standard charge cycle. If the pack was stored below roughly 2.0V, recovery is unlikely and a replacement pack is the correct fix.