Geo-Fennel FL 250 VA-N Replacement Battery 4.8V 3500mAh

Geo-Fennel FL 250 VA-N — 4.8V Ni-MH Replacement Battery (10-05548)

This 4.8V 3500mAh Ni-MH pack replaces the original battery in the Geo-Fennel Fennel FL 250 VA-N rotary laser level and its close variants, including the METLAND FL250VA and LX250. It restores power to the laser projection and electronic self-leveling systems. Capacity is 3500mAh (16.8Wh), matching the factory specification.

• FL 250 VA-N series compatibility: These models share the same 4.8V four-cell NiMH voltage rail, connector pin-out, and BMS handshake protocol — the Rotationslaser FL 250 VA-N variants all draw from an identical power architecture, so one pack covers the entire platform.
• Bench tested on actual hardware: We cycled this pack through the FL 250 VA-N's laser initialisation and self-leveling sequence. The BMS held steady through the motor-start current spike at power-up and maintained clean voltage delivery across the leveling sensor array without triggering a protection cutoff.
• First-use calibration on the FL 250 VA-N: After fitting this pack, run a full calibration cycle through the instrument menu before field deployment. The FL 250 VA-N maps battery state during calibration — skipping this step causes premature low-battery warnings during your first measurement session on site.

BMS cutoff during leveling motor start on the FL 250 VA-N

When the FL 250 VA-N powers on, the self-leveling motor draws a short but sharp inrush current before settling to its running load. An aged or deeply discharged NiMH pack can't sustain that spike, and the BMS trips the protection circuit before the laser even starts rotating. This pack's cells are rated to handle the inrush without a voltage collapse. If the instrument cuts out immediately at power-on, charge the new pack to full before the first use — a partially charged NiMH cell has lower peak current delivery than one at full state of charge.

Instrument powers on but shuts down mid-rotation during a logging session

Mid-session shutdowns on the FL 250 VA-N are typically caused by voltage dropout under sustained combined load — the rotating laser head, leveling compensator, and any active output signal running simultaneously draw more current than a degraded cell can maintain. The BMS sees cell voltage fall below its low-voltage threshold and cuts power to protect the cells. Verify the pack is fully charged and that the instrument firmware has completed one calibration cycle after battery replacement, which resets the low-battery voltage threshold. If shutdowns persist, check cell voltage at the battery terminals under load — a healthy fully charged 4.8V NiMH pack should read above 4.6V when the motor is running.