Leica ATX1200 Replacement Battery 7.4V 4400mAh GBE221

Leica ATX1200 / GRX1200 Series — 7.4V Li-ion Replacement Battery (GBE221)

This 7.4V 4400mAh Li-ion battery replaces the Leica GBE221 in ATX1200 robotic total stations, GRX1200 GNSS receivers, Piper 100, Piper 200, and over 23 additional Leica survey instruments. It matches the original cell count, connector, and BMS communication expected by the instrument firmware. Capacity figures are from product data — 4400mAh / 32.56Wh.

• ATX1200 and GRX1200 platform fit: Both instruments share the same battery bay geometry, 7.4V supply rail, and GBE221 connector pinout. The BMS handshake uses the same data line, so one cell pack covers the full platform without firmware conflicts.
• Bench tested on actual hardware: We cycled this pack through instrument power-on, motor drive initialisation on the ATX1200 drive train, and sustained GNSS signal logging on the GRX1200. The BMS held voltage above cutoff across all three load stages without tripping.
• First-use calibration on survey instruments: After installing, run a full battery calibration cycle through the instrument's system menu before field deployment. Leica instruments map battery state during that cycle — skipping it causes the low-battery warning to fire well before actual depletion on the first measurement session.

BMS cutoff during ATX1200 motor initialisation on startup

When the ATX1200 powers on, the drive motor draws a short current spike as it initialises the horizontal and vertical axes. A new pack with a partially discharged or cold cell can read a brief voltage sag that triggers BMS overcurrent protection. The instrument loses power before the first angle is measured. Charge the pack fully to 8.4V before the first field session — a partial charge means the cells have less headroom to absorb that motor-start spike without the BMS reacting.

Instrument shows inconsistent battery percentage after pack swap

After fitting a new cell, the ATX1200 and GRX1200 may display a percentage that jumps erratically — showing 80%, dropping to 40%, then climbing again within the same session. This happens because the instrument's voltage-threshold indicator is still calibrated to the discharge curve of the old, degraded cells. The new pack's voltage at any given state-of-charge sits higher than the instrument expects. Run two full charge and discharge cycles through normal field use, then perform the calibration routine in the system menu — the indicator stabilises once the firmware has mapped the new curve.