When the dynamic BMS data required by Article 14 and Annex VII of the EU Battery Regulation (Regulation (EU) 2023/1542) is linked to the battery passport[1], the variable that determines data volume is not the sampling period but which layer retains what. At a site of roughly 100 MWh (111,488 cells, assumed), retaining all raw cell data at 1 s accumulates 42.2 TB per year and 421.9 TB over 10 years, whereas aggregating the Annex VII parameters into daily rack-level records yields about 0.05 GB per year, roughly 1/840,000 of that. Conversely, sampling a 20 s abnormal event at a 60 s period drops the detection probability to 33.3%. A…