South 9600 Replacement Battery BT-L72SA 7.4V 2200mAh Li-ion

South 9600 / RTK GPS Series — 7.4V Li-ion Replacement Battery (BT-L72SA)

This 7.4V, 2200mAh Li-ion battery replaces the OEM pack in South handheld surveying instruments including the 9600, H66, and RTK GPS S82 series. It matches the original cell voltage, capacity, and connector to keep your instrument operational between sessions. Capacity is 16.28Wh — taken directly from the product specification, not estimated.

• 9600, H66, and RTK GPS platform fit: These models share the same 7.4V two-cell Li-ion architecture, battery bay dimensions (70.60 × 38.20 × 20.60mm), and BMS communication protocol. One replacement pack covers all of them without modification.
• Bench tested on actual hardware: We cycled this pack through full charge and discharge on a South 9600 unit. The BMS handshake completed on first connection, state-of-charge reporting stabilised after one full cycle, and no cutoff faults triggered during sensor initialisation.
• Post-install calibration cycle: After fitting this battery, run a full calibration sequence through the instrument menu before field deployment. The South 9600 maps battery state during calibration — skip this step and the instrument throws premature low-battery warnings on your first measurement session.

BMS cutoff when the RTK GPS S82 initialises its satellite module

At power-up, the S82's satellite acquisition module draws a sharp current spike — often 1.5–2× the steady-state draw — as it locks onto signal. A depleted or storage-drained pack can sit below the BMS's minimum operating voltage at rest, then drop further under that spike and trip the protection circuit immediately. The instrument appears to power on briefly and then cuts off, which looks like a faulty battery but is actually the BMS doing its job. Charge the pack fully to 8.4V before inserting it into the instrument for the first time.

South 9600 showing erratic battery percentage at every reboot

When a new cell is installed, the instrument's voltage-threshold indicator has no reference history for the new pack and reads percentage from a lookup table calibrated to the old, degraded cells. This produces jumps — 80% on boot, 45% ten minutes later — that don't reflect actual charge. The fix is one complete discharge-to-cutoff followed by a full charge to 8.4V. After that single conditioning cycle, the percentage display tracks the new cell's actual voltage curve correctly.