A battery pack consists of multiple battery cells that are techically interconnected to form a single unit. By choosing the appropriate cell types (usually identical) and circuit configuration (series, parallel or mixed connection), it is possible to create battery packs with practically any voltage, current level and capacity.

In addition to the cells themselves, battery packs also contain other components, such as:

spacers and connectors (e.g. H-type, Y-type) for electrically and mechanically
connecting the individual cells to each other;
leads and plugs or soldering lugs, or contact connections for connecting the
battery pack to the consumer and the charger;
protection and control electronics, e.g. to protect against overheating or
explosions, for monitoring power limiting, function or aging and for charging

A battery pack always fulfills more or less sophisticated housing functions as well. In the simplest case, the components are simply attached in a short-circuit-proof manner (e.g. using shrink sleeves), whereby care must be taken that heat dissipation and mechanical stability are sufficient. In more complex cases, a sturdier housing (e.g. plastic half-shells) must protect the battery pack against hostile ambient conditions or an injection-molded housing according to customer specifications is required to ensure seamless technical and optical integration of the battery pack as a system component of a device, such as an easily interchangeable battery pack of a power tool.