Over the past decade, Systems Engineering has switched from document-centric approaches to model-based ones. In this context, Model Based System Engineering (MBSE) and Multidisciplinary Design Analysis and Optimization (MDAO) have emerged as two complementary disciplines. How to combine MBSE and MDAO approaches for the benefits of systems engineers is still an open issue. This paper discusses a case study of coupling MBSE and MDAO. The MBSE part relies on SysML and timed automata, two modeling languages that are supported by the TTool and UPPAAL-SMC tools, respectively. The MDAO part is developed in the context of Open MDAO. The paper uses a drone as a case study and focuses discussion on battery usage. The SysML model of the drone is enhanced with a timed automata model of the battery. The SysML model of the battery is populated with results from MDAO analysis. In this context, combining SysML, UPPAAL-SMC and Open-MDAO offers to improve self-confidence in some values lying in the model, improve self-confidence in the requirements satisfaction, as well as to refine some requirements values with better accuracy.