This paper presents a cell-level time-series data management structure for a cloud-based wireless battery management system. The background and necessity of continuous cell-level data collection in wireless battery monitoring environments are described. A data management framework for collecting and transmitting cell-level measurement data to the cloud is defined. The overall system architecture consisting of the battery module, wireless communication unit, and cloud-based data management layer is presented. Experimental results demonstrate the storage and visualization of cell-level battery data using the proposed system.