This paper presents the architecture, simulation, construction, and testing results of a generalized programmable smart battery management system (BMS). The ultimate objective of the system is to extend the lifespan of a rechargeable battery pack (RBP). This is achieved by monitoring all the charging and discharging parameters and conditions of the battery pack and preventing any parameter that may adversely affect the lifespan of the pack exceeding pre-set limits. This is done whilst the battery pack is in-situ alleviating the need to disconnect any load connected to it, which is a major advantage. Further, the system is managed by a microcontroller and is software reconfigurable allowing the user to program it so as to match certain conditions and parameters of a given battery pack, which gives its versatility. The system was simulated, using MultiSim software, and a laboratory hardware module was constructed and tested. The simulation and practical results were in good agreement.