Flexing battery holders with integrated spring

thingiverse

For my electronics projects, I often require versatile battery holders in various sizes and configurations, such as single cells or multiple cells connected in parallel, series, or with serial lithium-ion type cells featuring balanced charging connectors between each cell. This project's objective was to develop fully parameterized and printable battery holders for cylindrical cells of arbitrary size and number. To complicate things further, I aimed to design a system where the battery could securely rest inside its holder without relying on a conventional metallic spring found at the minus pole. Instead, I incorporated a flexible printed coil structure that firmly presses the contacts onto the battery. The added advantage of this plastic spring is its elasticity of around 1-2mm, making it perfect for inserting and removing cells with ease. I can easily craft connections for the positive and negative terminals using insulated wires wrapped into simple windings. Each cell compartment comes equipped with several holes allowing wires to pass through to external locations as well as to adjacent compartments, which enables easy parallel, series, or balanced-serial configuration of battery packs. Moreover, a system of wire channels exists on the case bottom that facilitates exterior connections of wires from inside the holder. The ideal choice of material here for the flexible plastic spring was ABS due to its inherent flexibility, which I paired with an acetone-absorbed layer called "ABS slur" that acts as a natural insulation coating on exposed poles.