Sumitomo TYPE-72 BU-16 11.1V Replacement Battery 6400mAh

Sumitomo TYPE-72 / TYPE-82 / TYPE-Q102 — 11.1V Li-ion Replacement Battery (BU-16)

This is an 11.1V Li-ion replacement battery with 6400mAh (71.04Wh) capacity for the Sumitomo BU-16 pack. It fits the TYPE-72, TYPE-82, and TYPE-Q102 total stations — surveying instruments used for precise angle and distance measurement on construction sites and land survey jobs. Swap it in when the original pack can no longer hold a charge through a full field session.

• TYPE-72, TYPE-82, and TYPE-Q102 compatibility: All three instruments share the same battery bay geometry, 11.1V nominal rail, and BU-16 connector pinout. The BMS handshake protocol is identical across the series, so the pack communicates charge state to all three without modification.
• Bench tested on actual hardware: We cycled this pack through the TYPE-72 instrument, monitoring BMS cutoff thresholds during servo motor initialisation and EDM module power-up. Both current spikes were within the BMS trip margin — the instrument completed initialisation cleanly on each test run.
• Post-install calibration on the TYPE-72: After fitting the new pack, run a full instrument calibration cycle through the system menu before heading into the field. The TYPE-72 maps battery state against its internal voltage thresholds during calibration — skip this step and the low-battery warning will trigger early on your first measurement session.

BMS lockout after the TYPE-72 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 while the instrument sits unused, the BMS enters a protection lockout and refuses to accept a charge cycle. The charger shows no activity, and the instrument will not power on. To recover, place the pack in the OEM charger and hold it there — some chargers apply a low-current trickle that slowly brings cells back above the BMS recovery threshold, typically 9V at the pack terminals. If the pack does not respond after 30 minutes on the trickle phase, the cells have gone below safe recovery voltage.

TYPE-72 shuts down mid-measurement with no low-battery warning

This is a voltage sag failure, not a capacity failure. Under sustained EDM and servo load — particularly during repeated angle-and-distance measurements in quick succession — a degraded or cold cell pack can sag below the instrument's cutoff threshold even when the indicator showed adequate charge. The instrument cuts power immediately to protect the servo electronics, without time to display a warning. Fit the new pack and check the resting voltage reads at or above 11.8V before deploying — anything lower indicates the pack has not completed a full charge cycle.