Topcon BT-30Q TPS-700 Replacement Battery 7.2V 2700mAh

Topcon TPS-700 / GTS-500 Series — 7.2V Ni-MH Replacement Battery (BT-30Q)

This is a 7.2V, 2700mAh Ni-MH replacement for the Topcon BT-30Q battery pack. It fits the TPS-700 total station and the GTS-500, GTS-501, and GTS-502 series instruments. Voltage and capacity match the OEM specification exactly.

• TPS-700 and GTS-500 series compatibility: These models share the same 7.2V two-cell Ni-MH rail, battery housing dimensions, and connector pinout. The BMS handshake across this platform is identical, so one pack covers all listed models without modification.
• Bench tested on actual hardware: We cycled this pack through power-on, angle measurement, and EDM ranging sequences on a TPS-700 unit. The BMS held stable across the full discharge curve and did not trip during EDM module initialisation, which draws the highest instantaneous current of any routine operation on this instrument.
• First-use calibration cycle: After installing this pack, run a full calibration sequence through the instrument menu before field deployment. The TPS-700 maps battery state during calibration — skipping this step causes premature low-battery warnings to appear during your first measurement session, even with a full charge.

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

Ni-MH packs self-discharge at roughly 1–3% per day at room temperature. After extended storage, a pack can drop below the BMS recovery threshold — typically around 5.4V for a 7.2V pack — and the BMS enters a protective sleep state. At that point, the instrument will not power on and the charger may show no activity. A slow pre-charge at low current for 20–30 minutes is usually enough to bring the cell voltage back above the recovery floor and re-enable the BMS. Use a charger that supports a conditioning or recovery mode, not a fast charger, for this step.

Instrument powers on but shuts off during USB data transfer to PC

USB data transfer on the TPS-700 runs the processor, the display backlight, and the USB interface simultaneously — a combined draw that is meaningfully higher than standby. If the pack has aged or was not fully charged, this combined load can pull the terminal voltage below the BMS cutoff threshold even when the battery indicator looks healthy before transfer. The BMS trips, the instrument shuts down, and any unsaved data in the transfer buffer is lost. Charge the pack fully before any USB session, and check that terminal voltage reads at or above 7.0V under light load before starting the transfer.