Modular lithium-ion battery system for fork lifts

Many embodiments involve rechargeable battery assemblies that are forklift-battery-sized but that comprise multiple removable battery modules. The removable battery modules are individually rechargeable and are interchangeable with each other. A housing contains six battery modules installed vertically on the front side of the assembly, with their electrical and data connections occurring within the housing on the rear side. Assemblies will be two sided so that the system has two racks with six modules per rack. The handles of each module are collapsible and on the top edges of the overall assembly so that they are readily accessible during removal. Each battery module has an integrated battery supervisor system (BSS). A Battery Operating System Supervisor (BOSS) module processor serves as a battery management system for the all the battery modules. The BOSS module grants permissions to battery modules to enable them to connect and disconnect from busbars at the appropriate times to prevent electrical issues.