Efforts to reduce resource waste and utilize limited resources effectively have been a primary concern in the manufacturing industry. Circular supply chain models were developed to collect and reuse products in the market. However, traditional models have mainly focused on reusing collected parts for the same product. This paper proposes a novel operation model that reduces the wastage of parts by converting the recovered parts into different products according to their degree of functional deterioration. The conversion of electric-vehicle lithium-ion batteries to forklift and storage batteries was considered, and the performance of the model was verified using an event simulator.