Spectra Precision Focus 6 Replacement Battery 3.7V 6400mAh

Spectra Precision Focus 6 / Focus 8 — 3.7V Li-ion Replacement Battery

This 3.7V Li-ion battery at 6400mAh (23.68Wh) replaces the original pack in the Spectra Precision Focus 6 and Focus 8 robotic total stations. Both instruments run the same battery form factor, connector, and BMS handshake protocol. Dimensions are 67.90 × 39.50 × 25.60mm — confirm against your existing pack before ordering.

• Focus 6 and Focus 8 shared platform: Both total stations use identical battery bays, voltage rails, and BMS communication lines. A single cell format serves the full pair, which is why one replacement SKU covers both units without modification.
• Bench tested on actual hardware: We cycled this pack through the instrument's power-on sequence, servo initialisation, and EDM ranging burst. The BMS held steady through motor-drive current spikes without tripping into protection mode.
• Pre-deployment calibration cycle: After fitting this battery, run a full calibration sequence through the instrument's onboard menu before heading to site. The Focus 6 and Focus 8 map battery state during calibration — skipping this step causes premature low-battery warnings during your first measurement session, even with a fully charged pack.

BMS cutoff during servo motor initialisation on the Focus 6

When the Focus 6 powers on, it runs an automatic servo initialisation sweep that briefly spikes current draw beyond normal operating load. An aged or deeply discharged replacement pack can hit the BMS overcurrent threshold at exactly that moment, cutting power before the instrument fully boots. This is a cell-condition issue, not a firmware fault. Charge the new pack to 4.2V before first use and allow the BMS to complete one full charge cycle — this pre-conditions the protection circuitry for the motor-start surge.

Battery percentage jumping or resetting between power cycles

The Focus 6 and Focus 8 display fuel gauge readings tied to voltage thresholds stored from the previous pack. A new cell with different internal resistance will report inconsistent percentages — often jumping from 80% to 20% — until the instrument recalibrates its reference points. Run two full discharge-recharge cycles through normal field use without interrupting mid-charge. After the second cycle, the display percentage will stabilise and track accurately against actual cell voltage.