Last fall I bought a 2015 Leaf with an unknown to me battery issue. The car only managed 25km. I cracked open the battery, balanced the faulty cell, and now get 100+km of winter range
Here is the full buildthread in English for anyone interested: http://www.japtoys.net/forum/viewtopic.php?f=10&t=3613
I'm so excited, and in the process of figuring out how to open my own garage for servicing,replacing and upgrading Nissan Leaf's! If you are situated in Finland, out of battery warranty, I might be able to help