It is well known that the cost of batteries has been declining for the last couple of decades. Given that, I find the following graph puzzling:
From the St. Louis Fed, it shows the producer price index for battery manufacturing. This industry PPI has gone from 100 in 2004 up to 150 for the 2012-16 period. It is currently at 187. To overcome these increases there must be some strong increases in manufacturing efficiencies.