GeoMax ZT80+ Survey Instrument Replacement Battery 7.4V 2800mAh ZBA400

GeoMax ZT80+ / Zoom Series — 7.4V Li-ion Replacement Battery (ZBA400)

This 7.4V 2800mAh Li-ion pack replaces the ZBA400 and ZBA200 batteries used in the GeoMax ZT80+ total station and related Zoom and Stonex R6 instruments. It fits instruments that share the same battery bay geometry and 7.4V power rail across the ZT80+, Zoom 20, Zoom 30, and Stonex R6 platforms. Capacity is 2800mAh (20.72Wh) as rated.

• Cross-platform fit — ZT80+, Zoom 20, Zoom 30, Stonex R6: These instruments share a common battery form factor, connector pinout, and 7.4V supply rail. The BMS communication handshake is consistent across the platform, so the pack registers correctly in each instrument's power management system without modification.
• Bench tested on actual hardware: We cycled this pack through instrument power-on, angle measurement, and EDM ranging sequences. The BMS held voltage within spec under the combined draw of the display, motor drive, and ranging module. No mid-cycle cutoff was observed during sustained measurement sessions.
• First-use calibration on the ZT80+: After fitting a new pack, run a full calibration cycle from the instrument menu before heading to site. The ZT80+ maps battery state during calibration — skipping this step causes the low-battery indicator to trigger early on the first measurement session, even with a full charge.

BMS lockout after the ZT80+ sat unused in a carry case for months

Li-ion cells self-discharge during storage. If the pack drops below approximately 2.5V per cell while unused, the BMS trips into deep-discharge protection and the instrument will not power on at all — it looks like a dead battery even on a charger. The pack needs a low-current recovery charge before normal charging can resume. Place it on the GeoMax charger and leave it for at least 30 minutes before expecting the charge indicator to respond. If the charger does not acknowledge the pack after an hour, the cells have dropped below the BMS recovery threshold of around 2.4V per cell.

ZT80+ display shows incorrect battery percentage at every reboot

A new pack has a different internal resistance profile than the worn cell it replaced. The instrument's voltage-threshold indicator was calibrated to the old cell's discharge curve, so the percentage reading is unreliable for the first several charge cycles. This is not a fault with the pack — it is the instrument recalibrating its state-of-charge estimate. Run three full charge-discharge cycles in normal field use and the percentage readout will stabilise. Do not rely on the percentage display for field planning until after those initial cycles.