Topcon FC100 BT-30 Replacement Battery 7.4V 2200mAh

Topcon FC100 / FC2000 Field Controller — 7.4V Li-ion Replacement Battery (BT-30)

This 7.4V, 2200mAh Li-ion pack replaces the OEM BT-30 battery in the Topcon FC100 and FC2000 Field Controllers. These are handheld data collection units used in surveying, construction layout, and GPS field work. It also cross-references OEM part numbers BT-62Q, BT-65Q, and BT-66Q for extended model coverage.

• FC100 and FC2000 platform fit: Both controllers run the same 7.4V battery rail and share a common connector footprint and BMS handshake protocol. One pack covers both units without modification.
• Bench tested on actual hardware: We cycled this pack through the FC100's power-on sequence and GPS initialisation load. The BMS held stable under the combined draw of the display backlight, GPS module, and data logging — no false cutoff events recorded.
• Pre-deployment calibration cycle: After installing this pack, run a full calibration cycle through the FC100's instrument menu before heading into the field. The controller maps battery state during that sequence, and skipping it causes premature low-battery warnings to appear before actual capacity is depleted.

FC100 BMS lockout after the pack sat unused in a carry case for months

Li-ion cells left dormant below roughly 2.5V per cell will cause the BMS to enter a protective sleep state. In this condition the FC100 shows no charge indicator and may not respond to the charger at all. The fix is to apply a low-current trickle charge — most OEM Topcon chargers will attempt a recovery cycle automatically if left connected for 15 to 30 minutes. Once cell voltage recovers above the BMS wake threshold (approximately 6.0V across the pack), normal charging resumes.

GPS readings reset or logging session drops mid-session with no low-battery warning

This happens when sustained GPS and sensor load pulls the pack voltage below the FC100's brownout threshold momentarily — not a full discharge, just a voltage sag under load. The controller interprets the sag as a fault and resets the active session. A new cell pack with low internal resistance holds voltage more consistently under that combined draw. After fitting the replacement, confirm resting voltage reads at or above 8.2V before starting a logging session.