About this replacement
Topcon LS-B100 Series — 4.8V Ni-MH Replacement Battery (BT-68Q)
This is a 4.8V, 2000mAh Ni-MH replacement for the Topcon BT-68Q battery pack. It fits the LS-B100, LS-B110, LS-B110W, and LS-B100 Machine Control Laser. Cell count, voltage rail, and connector match the original pack specification.
- LS-B100 and LS-B110 series compatibility: These models share the same 4.8V four-cell Ni-MH architecture and BT-68Q connector pinout. The BMS expects identical cell impedance across all variants, so one pack covers the full range without modification.
- Bench tested on actual hardware: We cycled this pack through power-on, laser activation, and sustained levelling loads. The BMS held stable across full discharge and did not trip during the motor-drive initialisation pulse at startup.
- First-use calibration on the LS-B100: After installing, run a full calibration cycle through the instrument menu before field deployment. The LS-B100 maps battery state during calibration. Skipping this step causes premature low-battery warnings during your first measurement session — even with a fully charged pack.
LS-B100 shutting down mid-measurement despite showing adequate charge
Ni-MH cells develop internal resistance as they age, which causes voltage to sag sharply under the sustained draw of the laser diode and levelling motor running together. The instrument's undervoltage protection trips when pack voltage drops below the cutoff threshold — even briefly. A new pack with low internal resistance holds the voltage rail stable under that combined load. If shutdowns persist after fitting a new pack, check that the battery contacts in the instrument bay are clean and making full contact.
LS-B100 not recognising a new pack after the instrument sat unused for months
Ni-MH packs self-discharge during storage, and if the pack voltage drops far enough the instrument's battery detection circuit sees it as absent or faulty. The fix is to charge the pack fully before inserting it — do not install a pack straight from packaging into a stored instrument. After a full charge, insert the pack and power cycle the instrument. If the display still shows a fault, hold the power button for ten seconds to force a full BMS re-initialisation. The instrument should read normal battery status once pack voltage is above 4.6V at rest.