About this replacement
GeoMax ZTS 602LR Series — 6V Ni-MH Replacement Battery (ZBA-100)
This is a 6V 4100mAh Ni-MH replacement battery for the GeoMax ZTS 602LR, ZTS602, ZTS602S, and ZTS602LR total stations. These are professional surveying instruments used in land surveying and construction layout. This pack replaces OEM part ZBA-100 (also cross-referenced as 645465).
- ZTS 602 platform compatibility: All ZTS602 variants share the same 6V battery bay, connector pinout, and BMS handshake protocol. One pack covers the full model range — LR, S, and base — because GeoMax standardised the power module across this series.
- Bench tested on actual hardware: We cycled this pack through a ZTS602 instrument bench rig. The BMS negotiated correctly at startup, held stable voltage through angular measurement sequences, and showed no false low-battery cutoffs during EDM distance pulses.
- First deployment after installation: After fitting this pack, run a full instrument calibration cycle through the ZTS602 menu before heading to site. The instrument maps battery state during calibration. Skipping this step causes premature low-battery warnings to appear during your first measurement session in the field.
BMS lockout after the ZTS602 sat unused in a case for months
Ni-MH cells self-discharge over time. If the pack drops below approximately 4.5V total during storage, the BMS enters a protective sleep state and the instrument will not power on — even with a charger connected. The fix is a slow recovery charge at low current (typically 100–200mA) using a compatible external Ni-MH charger that can override the BMS sleep condition. Once the pack climbs back above the BMS wake threshold — around 5.0V — normal charging resumes and the instrument will recognise the pack again.
ZTS602 readings reset or drift mid-session under sustained EDM load
Extended distance measurement sequences draw sustained current from the pack — the EDM module and angle sensors run simultaneously, and voltage sag under this combined load can dip enough to trigger a momentary reset on the instrument's CPU. This is common when cells have partially degraded or when a new pack hasn't been fully conditioned. Run two full charge-discharge cycles before a long measurement session to let the cells reach stable capacity. If resets continue, check the terminal voltage under load — it should hold above 5.4V during active EDM sequences.