This product listing is for the internal replacement cells used to rebuild or repair the FOIF BT43 battery pack. Instead of replacing the entire outer housing, these high-grade lithium-ion cells allow you to restore your battery’s original capacity and performance at a fraction of the cost.

Product Overview

The FOIF BT43 battery is a 7.4V system typically found in the FOIF RTS100, RTS112, and OTS650 series total stations. Internally, this pack is powered by a 2S (2-Series) configuration of industrial 18650 cells. These replacement cells are specifically selected for their high energy density and stable discharge rates, essential for the Electronic Distance Measurement (EDM) and motorized functions of your surveying instruments.

Key Features

• Grade-A 18650 Chemistry: High-quality lithium-ion cells (typically sourced from Samsung, Panasonic, or LG) designed for thousands of hours of field operation.

• Optimized Capacity: Available in 3400mAh to 3500mAh variants, often providing a 10-20% runtime increase over older, factory-standard cells.

• Low Internal Resistance: Ensures stable voltage delivery, preventing instrument "power-off" errors during high-drain laser measurements.

• Flat-Top Design: Precision-sized (18mm x 65mm) to ensure a perfect fit inside the tight dimensions of the original BT43 white or grey plastic casing.

• Sustained Cycle Life: Rated for 300–500 full charge/discharge cycles before reaching 80?pacity, matching or exceeding OEM longevity.

Technical Specifications

Installation Note

Rebuilding a BT43 pack requires basic soldering skills. You will need to carefully open the existing casing, desolder the old cells from the Battery Management System (BMS) circuit board, and spot-weld or solder the new cells in the same 2S configuration.

Safety Warning: Always ensure cells are handled with care to avoid short-circuiting. It is recommended to use cells with pre-attached solder tabs for easier and safer DIY installation.

In the Box:

• 2x High-Capacity 18650 Li-ion Cells (Unprotected, Flat-Top)