The battery is connected by a connecting bar. There are two types commonly used, copper bar (hard connection) and cable bar (soft connection). The copper bar is easy to manufacture and easy to install. However, due to the strong rigidity of the material, the pole may be damaged when connected or poor contact, soft cable connection to overcome the above shortcomings make the battery flexible and convenient connection, terminal surface contact performance is good. When connected in parallel with two or more batteries, ensure same length of each cable connection as long as possible to maintain relative homogeneity between the battery packs.