About this replacement
GeoMax Zipp10 / ZT20 Series — 7.4V Li-ion Replacement Battery (ZBA302)
This is a 7.4V, 4400mAh Li-ion replacement battery for the GeoMax Zipp10 total station and ZT20 / ZT20R / Zoom 20 series survey instruments. It replaces OEM part numbers ZBA302 and ZBA301. Capacity is sourced from the product specification — 32.56Wh cell pack, same footprint as the factory unit at 72.45 × 39.50 × 40.00mm.
- Zipp10 and ZT20 platform fit: These models share the same battery bay geometry, 7.4V nominal voltage rail, and two-pin communication interface. The BMS handshake protocol is identical across the Zipp10, ZT20, ZT20R, and Zoom 20, so one cell pack serves the full lineup without modification.
- Bench tested on actual hardware: We cycled this pack through instrument power-on, EDM activation, and sustained angle-logging sequences. The BMS held voltage within spec across the angular encoder and EDM discharge spikes, with no spurious low-battery interrupts during active measurement sessions.
- Pre-deployment calibration cycle: After fitting this battery, run a full calibration cycle through the instrument menu before taking it into the field. The Zipp10 and ZT20 map battery state during calibration — skip this step and the instrument will flag premature low-battery warnings on the first measurement session.
BMS lockout after the instrument sat in a carry case for months
Li-ion cells in a stored total station can drift below 2.5V per cell during extended inactivity. When that happens, the battery's BMS enters a protective sleep state and the instrument will not power on — it looks like a dead battery even after placing it on the charger. Most GeoMax chargers require the pack to present a minimum voltage before initiating a charge cycle, so a deeply discharged cell gets rejected. To recover the pack, connect it to the charger and hold it in place for 10–15 minutes — some chargers trickle at low voltage before the main charge begins. If the charger still shows no activity after 20 minutes, the cells have dropped below safe recovery threshold at approximately 2.0V per cell.
Readings resetting or logging gaps during a sustained data-collection session
Sustained sensor load — continuous EDM ranging combined with onboard data logging — draws more current than standby or single-shot measurements. If the cell voltage sags under that combined load, the instrument's processor can momentarily lose power and reset mid-session, producing a gap in the logged data set. This is not a firmware issue — it is a voltage dropout caused by a weakened or partially discharged cell. Before a long logging session, confirm the battery reads at or above 8.0V on the instrument's status screen, which corresponds to approximately 80% charge on a healthy 7.4V pack.