Just playing around again looking at the log file dump from the Roadster and I totally missed this before, the ahr.log file. It shows the previous/current SOC and the previous/current voltage of each brick in the ESS numbered 0 to 99 (11 sheets, 9 bricks in each). Here's a sample clip from my old log file: brick prevSOC prevV presSOC presV 0 625459 31687 619510 31647 1 625459 31687 619510 31647 2 625459 31690 620691 31651 Just curious about when / what time they take these snapshots. But over time you can correlate your drop in CAC to the brick/sheet as long as you dump and save your logs regularly. This also looks familiar to the graphical ESS brick/sheet tool Tesla has in their arsenal that shows what's really going on inside the battery pack, all for the exception that Telsa's tool shows the Ah capacity of each brick as well as sheet.