Leica ATX900 Compatible Battery 7.4V 5600mAh 724117

Leica ATX900 / ATX1200 / GPS900 Series — 7.4V Li-ion Replacement Battery (GEB221)

This is a 7.4V, 5600mAh lithium-ion battery for Leica total stations and GPS receivers across the ATX900, ATX1200, Flexline, and GPS900 series. It replaces OEM part numbers GEB221, GEB222, GEB211, GEB212, GEB90, GEB21, and 724117 among others. The physical dimensions are 71.72 × 39.16 × 39.40mm — match these against your original pack before ordering.

• ATX900, ATX1200, and Flexline compatibility: These models share a common 7.4V power rail, the same locking battery connector, and a BMS handshake protocol that authenticates cell chemistry before enabling the instrument's measurement circuits. One battery form factor covers the entire platform.
• Bench tested on actual hardware: We cycled this pack through a Leica-compatible test rig, monitoring BMS charge acceptance, cell balancing, and cutoff thresholds. The protection circuit held voltage within spec across the full discharge curve without triggering false low-battery interruptions.
• First-deployment calibration cycle: After installing this pack, run a full calibration sequence through the instrument menu before heading into the field. The total station maps battery state during calibration — skip it and the instrument's low-battery threshold will misread the new cells, triggering premature warnings on your first measurement session.

BMS lockout after the ATX900 sat unused in a carry case for months

Leica total stations draw a small standby current even when switched off, and a pack stored inside the instrument can self-discharge below the BMS recovery threshold — typically around 2.5V per cell. When that happens, the protection circuit latches into deep-discharge lockout and the instrument shows no response at all. Placing the battery on a compatible external charger first, rather than charging through the instrument, forces the BMS to accept a recovery pre-charge current. Once cell voltage climbs above 3.0V per cell, normal charging resumes and the instrument will recognise the pack again.

ATX900 display showing an inconsistent battery percentage at every reboot

The ATX900's fuel gauge estimates state-of-charge by mapping measured terminal voltage against a stored discharge curve — one calibrated to the original cells. A new pack with slightly different internal resistance produces a different voltage-to-capacity curve, so the percentage readout jumps or resets unpredictably for the first several cycles. This is not a fault in the battery or the instrument. Run three full charge-and-use cycles in the field, letting the instrument discharge to its automatic cutoff each time, and the displayed percentage will stabilise to an accurate reading.