Sokkia Juniper Mesa 7.4V 3400mAh Replacement Battery 61117

Sokkia Juniper Mesa Field / Topcon Tesla — 7.4V Li-ion Replacement Battery (61117)

This 7.4V 3400mAh Li-ion battery replaces OEM part 61117 and 20545 in the Juniper Mesa Field data collector and Topcon Tesla series. Both devices are handheld survey instruments used for GPS positioning and land data collection. The pack slots into the same battery bay and communicates with each instrument's power management system.

• Juniper Mesa Field and Topcon Tesla compatibility: Both platforms run a 7.4V two-cell Li-ion architecture with the same connector pinout and BMS handshake protocol. The battery's protection circuit matches the charge termination voltage and discharge cutoff each instrument expects — no firmware mismatch on either platform.
• Bench tested on actual hardware: We cycled this pack through GPS lock acquisition and active data logging on both platforms. The BMS held steady through the sustained sensor load without triggering an early cutoff, and charge acceptance across three cycles matched the rated 3400mAh within a 2% margin.
• Instrument calibration before first field deployment: After installing a new pack, run the battery calibration routine from the instrument's system menu before heading into the field. The Mesa Field and Tesla both map state-of-charge thresholds during this routine — skipping it causes the low-battery warning to fire prematurely on the first logging session.

BMS cutoff when the Mesa Field or Tesla initialises its GPS module

On cold boot, both instruments draw a sharp current spike as the GPS module powers up and begins satellite acquisition. An aged or deeply discharged original pack can drop below the BMS cutoff threshold at this exact moment, causing the device to shut off immediately after the splash screen. This replacement pack's cells handle the inrush without tripping the protection circuit because the internal resistance is lower than a worn original. If the shutdown persists, charge the pack to full and reboot — cell voltage needs to be above 8.0V before the GPS init spike hits.

Data logging session cuts out mid-record with no low-battery warning

This happens when the instrument's state-of-charge indicator is calibrated to an old cell's discharge curve and doesn't anticipate the real voltage floor of a new pack. The device reads 30–40% remaining on the display, then shuts off as the cells hit the BMS protection threshold under sustained sensor load. It is not a faulty pack — it is a threshold mismatch caused by skipping the calibration cycle on installation. Run the full calibration sequence from the system menu and the instrument will recalibrate its indicators to the new cell's curve.