Carlson Zoom Total Station Replacement Battery 7.4V 2800mAh

Carlson Zoom Mechanical Total Station — 7.4V Li-ion Replacement Battery

This 7.4V, 2800mAh (20.72Wh) lithium-ion battery fits the Carlson Zoom series of mechanical total stations. These instruments are used in construction layout, land surveying, and engineering fieldwork — environments where a battery failure mid-session costs real time and money. Voltage and capacity match the original pack specification.

• Carlson Zoom platform fit: The Zoom series runs a 7.4V two-cell Li-ion architecture with a BMS that monitors cell balance and current draw during EDM ranging and angle encoder reads. Both functions pull from the same rail, so the pack must hold voltage steady under combined load — not just during idle.
• Bench tested on actual hardware: We cycled this pack through power-on, EDM activation, and sustained angle logging sequences. The BMS handled the initialisation current spike at instrument startup without tripping and maintained stable output through multi-point measurement runs.
• First deployment after storage: Run a full calibration cycle through the instrument menu before your first field session. The Zoom maps battery state during calibration — skipping this step causes the low-battery warning to trigger early and incorrectly on the first measurement session.

Why the Zoom shuts down when the EDM module fires

The EDM ranging module on the Zoom draws a short, sharp current spike the moment it activates — significantly more than the idle draw of the display and encoder. A degraded or deeply discharged pack cannot hold voltage above the BMS cutoff threshold during this spike. The instrument reads this as an undervoltage event and shuts off to protect the electronics. This is not a firmware fault — it is the BMS doing exactly what it should when cell voltage collapses under load.

Battery percentage jumping around or resetting at reboot

The Zoom uses a voltage-threshold method to estimate charge level — it does not track capacity continuously. When a new pack is installed, the instrument has no learned reference for that cell's discharge curve, so the indicator reads erratically until it accumulates data across a full discharge cycle. Run the instrument from a full charge down to the low-battery warning once, then recharge completely. After that single cycle, the percentage display stabilises and tracks correctly through subsequent sessions.