Protecting sensitive surfaces from dust deposition in the limiting condition of the lunar atmosphere is imperative for space exploration. In this study, how back electrostatic field due to charge build-up on collection plates may affect the performance of an electrostatic lunar dust collector (ELDC) was investigated. The relationships between ELDC dimensions, collection efficiency and electrical properties of lunar dust particles were derived to develop a model, appropriate for any size of the ELDC. A Lagrangian-based discrete element method (DEM) was applied to track particle trajectories, and sensitivity analyses were conducted for the concentration of the incoming particles, the number of pre-collected particles and the applied voltages. The results revealed that the collection efficiency reduced over time due to the back electrostatic field of the collected particles, which ultimately led to a suspended regime, rather than just collected and penetrated fractions considered in conventional models. The generated back electrostatic field and the cloud of suspended particles were strong enough to disrupt the performances of both the ELDC and the protected device. The maximum time ELDC can run without significant loss in collection efficiency was estimated to be 10 terrestrial days for the studied ELDC size and applied voltage. Because the electrical power was negligible compared to the provided power by the solar panels, increasing the applied voltage was found to be the best option to counteract back electrostatic growth.