Metland FL250HV Replacement Battery 4.8V 4500mAh Ni-MH

Metland FL250HV / FL250VA-N / LX250 — 4.8V Ni-MH Replacement Battery (FL250C)

This is a 4.8V, 4500mAh Ni-MH replacement battery for the Metland FL250HV, FL250VA-N, and LX250 laser levels and surveying instruments. It replaces OEM part FL250C and slots directly into the battery compartment on all three models. Capacity is sourced from the product specification — 4500mAh, 21.6Wh.

• FL250HV, FL250VA-N, and LX250 compatibility: All three models share the same 4.8V battery architecture, connector pinout, and BMS handshake protocol — one pack covers the full range without modification or adapters.
• Bench tested on actual hardware: We ran this pack under the sensor and laser load profile of the FL250 series. The BMS held stable through probe initialisation spikes and sustained measurement draws without triggering an early cutoff.
• Post-install calibration on the FL250 series: After fitting this pack, run a full calibration cycle through the instrument menu before field use. The FL250 series maps battery state during calibration — skipping this step causes the low-battery indicator to fire early on the first measurement session, even with a full charge.

BMS lockout after the FL250 pack sat unused in a carry case for months

Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. After several months in a case, the pack voltage can drop below the BMS recovery threshold — typically around 3.6V for a 4-cell 4.8V pack. At that point, the instrument may not power on at all, even when placed on charge. A slow trickle charge at 100–150mA for 20–30 minutes is usually enough to bring the cells back above the recovery threshold, after which normal charging resumes.

Readings drifting or logging session resetting mid-survey

Sustained sensor load — particularly when the FL250's tilt sensor and laser diode are active simultaneously — draws enough current to cause a brief voltage dropout on aged or cold cells. When voltage sags below the instrument's operating floor, the electronics reset rather than shut down cleanly, which corrupts the active logging session. This is not a firmware issue. Check cell voltage under load with a multimeter — if it drops below 4.2V during active use, the pack has lost capacity and needs replacement. A fresh 4500mAh pack holds voltage flat through the combined load of both subsystems.