In September you posted that it was 'easy' to upgrade your CR-Z's under-hood battery.
I have had real problems this winter with mine (bought a 2015 CR-Z, 6-speed manual EX, new exactly three years ago). Finally had to have it replaced just last week. The dealer told me it wasn't possible to upgrade the under-hood battery; that what it shipped with was all that is allowed.
Can I ask which exact model CR-Z you have? Many thanks for posting!