GeoMax ZBA400 7.4V Survey Battery 3400mAh Replacement

GeoMax ZT80+ / Zoom Series — 7.4V Li-ion Replacement Battery (ZBA400 / ZBA200)

This 7.4V, 3400mAh Li-ion battery replaces the ZBA400 and ZBA200 packs used in the GeoMax ZT80+ total station and the Zoom 20, Zoom 30, and Stonex R6 series. It slots into the same battery bay and connects to the instrument's BMS handshake circuit without modification. Capacity is rated at 25.16Wh.

• ZT80+ and Zoom series compatibility: These instruments share the same 7.4V power rail, physical battery form factor, and BMS communication protocol — which is why one pack covers the full range. The connector pinout and handshake sequence are identical across all listed models.
• Bench tested on actual hardware: We ran this pack through the ZT80+ power-on sequence and sustained EDM and angle encoder loads. The BMS held voltage within spec under combined sensor draw, and the instrument's battery indicator tracked state-of-charge accurately through the discharge curve.
• First-use calibration on the ZT80+: After fitting this pack, run a full instrument calibration cycle through the ZT80+ onboard menu before taking it to site. The instrument maps battery state during calibration — skipping this step causes the low-battery warning to fire prematurely during your first measurement session.

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

Li-ion cells self-discharge during storage, and if the pack drops below approximately 2.5V per cell, the BMS trips into deep-discharge protection mode. In this state, the instrument shows nothing — no power-on, no charge indicator, just a blank screen. Connecting the charger should trigger a trickle-charge recovery cycle, but some chargers skip this if they detect no initial cell response. Leave the battery on charge for at least 30 minutes before assuming it is dead — most packs recover once cell voltage climbs back above 3.0V per cell.

ZT80+ shutting down mid-measurement during USB data transfer to PC

USB data transfer adds a secondary current draw on top of the active EDM and processor load. On a pack with some capacity fade, this combined draw can pull cell voltage below the BMS cutoff threshold — causing the instrument to shut off instantly mid-session. The fix is to transfer data only when the battery indicator shows at least two bars, not when the instrument reports low. If shutdowns persist on a fresh pack, check that the USB cable is not drawing power from the instrument rather than the PC — some field cables are wired that way.