This guide discusses the ventilation and thermal management of stationary battery systems as applied to the following: -- Vented (flooded) lead-acid (VLA) -- Valve-regulated lead-acid (VRLA) -- Nickel-cadmium (Ni-Cd) -- Partially recombinant nickel-cadmium. For each category, both the technology and the design of the battery are described in order to facilitate user understanding of the environmental issues associated with each type of technology. The scope of this document includes only stationary batteries under conditions of expected use. Multiple operating modes are identified. The ventilation practices described in this guide represent the "best practice" based on the information available at the time this document was developed. The user should evaluate these practices against their operating experience, operating conditions, number and size of battery systems, manufacturer's recommendations, resources, and needs in developing an environment that is conducive to safety and optimum operation of the equipment. These recommendations were developed without consideration of economics, availability of equipment and personnel, or relative importance of the application. Design of a ventilation system for a specific battery installation requires consideration of all issues, not just the technical issues considered in this document.