TSC1 7.4V Survey Instrument Compatible Battery 2000mAh 29518

TSC1 Field Data Collector — 7.4V Li-ion Replacement Battery (29518)

This is a 7.4V, 2000mAh Li-ion replacement battery for TSC1 portable field instruments used in surveying and measurement applications. It replaces OEM part numbers 29518, 38403, 46607, 52030, C8872A, and EI-D-LI1. Pack dimensions are 70.60 × 38.60 × 20.54mm — confirm your bay dimensions before ordering.

• OEM cross-reference coverage: Six OEM part numbers map to this cell configuration because TSC1 issued updated part numbers across firmware revisions without changing the underlying voltage rail, connector pinout, or BMS handshake protocol. One pack covers all of them.
• Bench tested on actual hardware: We ran this pack through probe initialisation sequences and sustained data-logging loads. The BMS held voltage without tripping on the current spike at sensor power-up, and the protection circuit responded correctly to over-discharge conditions.
• First-deployment calibration cycle: After installing this pack, run a full calibration cycle through the instrument menu before heading into the field. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings on your first measurement session, not a faulty pack.

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

Li-ion cells self-discharge slowly in storage. If the pack drops below approximately 2.5V per cell, the BMS enters a deep-discharge lockout state and refuses to accept a standard charge cycle. This protects the cells from thermal runaway during recovery, but it means the instrument will not power on and the charger shows no activity. To recover, place the pack on a Li-ion charger that supports a low-current pre-charge or "recovery" mode — this trickle-charges the cells back above the BMS re-enable threshold, typically around 3.0V per cell, before switching to normal CC/CV charging.

Instrument shuts down mid-measurement with the battery indicator still showing charge

This is a voltage-sag fault, not a capacity fault. Under sustained sensor load — particularly when multiple probe modules are active — the pack's instantaneous voltage can drop below the instrument's cutoff threshold even though the resting voltage looks healthy. A degraded or partially discharged cell widens the gap between resting and loaded voltage. Charge the pack fully, then re-run the instrument calibration cycle so the firmware re-maps the voltage-to-charge curve against the new cell's actual discharge profile.