Battery system with a plurality of batteries housed in an external case

The battery system houses a battery assembly 10 in an external case 2. The battery assembly 10 has a battery holder 11 that disposes the plurality of batteries 1 in multiple rows and columns. External outputs 9, which take battery 1 output outside the battery system, are connected to output lead-plates 3X disposed at the output-sides of the batteries 1. Lead-plates 3 connect all the batteries 1 in a single column in parallel and adjacent columns of batteries 1 in series. Multiple columns of batteries 1 are connected in series, and output lead-plates 3X and external outputs 9 are disposed at the positive and negative sides. In addition, the output lead-plates 3X are provided with battery connecting sections 3A that connect a plurality of batteries 1 in parallel, and output extensions 3B attached to the sides of the battery connecting sections 3A that connect to the external outputs 9.