Hemisphere S320 GNSS Replacement Battery 7.4V 3400mAh

Hemisphere S320 GNSS Receiver — 7.4V Li-ion Replacement Battery

This 7.4V, 3400mAh (25.16Wh) lithium-ion battery replaces the internal pack in the Hemisphere S320 and S320 GNSS survey receivers. The S320 is a multi-frequency GNSS positioning instrument used in geodetic survey, construction staking, and geospatial data collection. This pack matches the original voltage rail and physical envelope at 70.35 × 38.50 × 20.65mm.

• S320 and S320 GNSS compatibility: Both the S320 and S320 GNSS variants run the same 7.4V power architecture with an identical battery bay and connector. The BMS handshake is voltage-threshold based — no proprietary authentication chip — so the pack communicates state-of-charge to the firmware without modification.
• Bench tested on actual hardware: We cycled this pack through full charge and discharge under a simulated GNSS tracking load. The BMS held stable across satellite acquisition bursts and sustained RTK correction logging. No false low-voltage cutoffs were triggered during multi-constellation tracking.
• Post-install calibration cycle: After fitting this pack, run a full calibration cycle through the S320 instrument menu before heading into the field. The receiver maps battery state during that process. Skipping it causes premature low-battery warnings to appear during your first measurement session, even when the pack is near full charge.

BMS cutoff when the S320 initialises its satellite tracking engine

At power-on, the S320 pulls a short current spike as it initialises the RF front-end and begins satellite acquisition. If the battery's state of charge is below roughly 20%, that spike can push the cell voltage momentarily below the BMS protection threshold, triggering an immediate cutoff. The instrument shuts off before it ever reaches the main screen. This is not a firmware fault — it is the BMS protecting cells from a low-voltage load event. Charge the pack to at least 3.7V per cell before powering on after extended storage.

S320 shows erratic battery percentage across consecutive reboots

When a new or deeply discharged pack is first installed, the S320's voltage-threshold indicator has no prior reference for the new cell's discharge curve. It will show inconsistent percentages — sometimes jumping from 80% to 40% between reboots — until the firmware recalibrates to the actual cell behaviour. Run two full charge-to-discharge cycles in the field before trusting the on-screen percentage. After those cycles, the displayed level stabilises and tracks accurately against actual remaining capacity.