Trimble Juno 3A GPS Replacement Battery 3.7V 3060mAh

Trimble Juno 3 Series — 3.7V Li-Polymer Replacement Battery (707-00008-00B)

This 3.7V, 3060mAh lithium-polymer battery replaces the OEM pack in the Trimble Juno 3A, 3B, 3C, and 3D handheld GPS receivers. It fits the same battery bay and uses the same connector as the original. Capacity is rated at 11.32Wh — matching the draw profile of the Juno 3 platform during active GPS logging and data collection.

• Juno 3A / 3B / 3C / 3D platform fit: All four variants share the same voltage rail, battery bay dimensions, and BMS handshake protocol. One pack covers the full Juno 3 line without wiring or adapter changes.
• Bench tested on actual hardware: We cycled this pack through GPS acquisition, active Bluetooth, and continuous data logging. The BMS held steady at full load and triggered protection cleanly at the low-voltage threshold — no unexpected cutoffs.
• Post-install calibration cycle: After fitting this battery, run a full calibration cycle through the Juno 3 system settings before heading to the field. The device maps battery state during that cycle — skipping it causes the low-battery warning to fire well before the cell is actually depleted on your first survey session.

BMS cutoff when the Juno 3 initialises its GPS or Bluetooth module

At power-on, the Juno 3 pulls a short current spike as the GPS receiver and Bluetooth radio initialise simultaneously. A degraded or deeply discharged pack can drop below the BMS protection threshold during that spike, triggering an immediate cutoff — the unit appears to power on then shut straight back off. This is a cell-level issue, not a firmware fault. Charge the replacement pack to at least 3.9V per cell before the first boot to keep voltage above the cutoff window during initialisation.

Juno 3 shuts down mid-session during USB data transfer to a PC

USB data transfer adds a combined draw from the CPU, storage controller, and the charging circuit running in reverse — the device attempts to source current to the host in some cable configurations. This can push total draw above what a partially discharged pack sustains, and the BMS cuts the output rail. It is not a software crash. Start transfers with the battery above 50% charge, or use an externally powered USB hub to reduce the current demand on the pack during the transfer session.