Abstract: A power management system for providing power to a main system, such as a telecommunications device, includes a number of modules that are joined by module-to-module interfaces that achieve a common EMC containment barrier. In one embodiment, a battery module defines a first EMC compartment that houses one or more backup batteries, a battery management module defines a second EMC compartment that includes circuitry such as recharging circuitry, and a power entry module includes a third EMC compartment. The power entry module has an input/output connection to the battery management module and has an AC input. An output cable extends from the power entry module to the main system. Compliant metallic module-to-module gaskets preserve EMC integrity at cable pass-throughs from the battery management module to the battery and power entry modules. The modules are mounted to a system housing in a manner that secures the modules in a desired relationship.