Topcon SR GPS 7.4V 2600mAh Replacement Battery 1000001-01

Topcon SR GPS / Hiper GPS SR — 7.4V Li-ion Replacement Battery (1000001-01)

This is a 7.4V 2600mAh Li-ion replacement battery for the Topcon SR GPS, Hiper GPS SR, and TPSWT41 GNSS receivers. It fits the original battery slot with the same connector and BMS handshake as the factory pack. Capacity matches the product data at 19.24Wh — use this figure for field planning, not web-sourced estimates.

• SR GPS, Hiper GPS SR, and TPSWT41 compatibility: These three receivers share the same 7.4V battery bay, connector pinout, and BMS communication protocol. One pack covers all three without adapter or firmware modification.
• Bench tested on actual hardware: We cycled this pack through the SR GPS charge and discharge sequence and confirmed the BMS handshake triggers correctly at power-on. The protection circuit trips at the expected low-voltage threshold without nuisance cutoffs during normal GNSS logging loads.
• Post-install calibration on the SR GPS: After fitting a new pack, run a full calibration cycle through the receiver's system menu before field deployment. The SR GPS maps battery state during this sequence. Skipping it causes the charge indicator to show false low-battery warnings during the first survey session, which can interrupt data logging at the wrong moment.

BMS cutoff when the SR GPS initialises its satellite tracking module

At power-on, the SR GPS briefly draws a higher current spike as it powers the GNSS tracking board and internal oscillator simultaneously. A pack with a conservatively set protection circuit — or one that has sat discharged for weeks — can trip its BMS cutoff right at this moment, making the unit appear dead. The pack itself is not faulty; the BMS triggered on an inrush event. Reconnect the battery, allow 60 seconds for the BMS to reset, then power on again. If the cutoff repeats, charge the pack to at least 7.8V before the next power-on attempt.

GNSS position readings resetting or dropping during an active logging session

If the receiver resets or loses fix mid-session without warning, the cause is usually a brief voltage dropout under sustained sensor and radio load — not a satellite or firmware issue. The SR GPS draws steady current across its tracking board, internal memory write cycles, and any active data-link radio, and a degraded or low cell cannot hold voltage flat under that combined load. The dropout lasts only milliseconds but is long enough to trigger a soft reset in the receiver firmware. Check the pack voltage under load with a multimeter at the battery contacts — a healthy cell holds above 7.2V during active logging.