This study aims at highlighting the impact of the sizing of a hybrid multi-stack fuel cell battery system on its behavior. Using a rule based energy management strategy, the influence of the hybridization rating is studied. The system's fuel consumption, operation duration, start/stop cycles, ampere-hour throughput and state of charge deviation are evaluated using an Energetic Macroscopic Representation (EMR) based dynamic model. The simulation results predict and expected superiority in both fuel economy and system degradation for systems with a high hybridization ratings whereas the use of systems with low hybridization ratings results in a reduced battery depth of discharge. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.