This paper presents an application of a simple assembly line balancing problem (SALB) in a lead-acid battery factory in Colombia. SALBP-1 was the selected approach to carry out the research. In this type of SALBP, there is a fixed cycle time, and the purpose is to minimize the number of workstations. To this aim, a process characterization was conducted, and a mixed-integer linear model was formulated. Then, an exact solution was found using GAMS® software. The main findings included reducing the number of workstations from 10 to 4. This change impacted the line efficiency and the idle time achieving a 150% and a 94% improvement, respectively. This research demonstrated the impact of dealing with SALBP on production companies over the line performance in terms of idle time minimization and productivity increase.