Just thought I'd share my experience with Nissan's battery warranty.
My 2017 Nissan Leaf hit 8 bars recently, so I went to a dealership and applied for a replacement battery back in February of this year. They've allowed me to keep my car in the meantime, but it's been about 8 months and still no word on when a replacement battery will be available. I've called the dealership a couple times over the past several months to check on the status of the replacement, but they always just tell me that there are no battery shipments in sight, and that they have no idea when they'll be able to get me a replacement.
Eventually I got tired of waiting, so I called Nissan CA to inquire about a buyback. They called me back the very next day and said that they were going to decline to offer a buyback, citing that my car was not in bad enough condition to qualify for one or something, and that I should just continue waiting for a battery. I asked them if they knew when a battery would be available and they said they had no idea. I didn't bother arguing with them, and I instead just opened a case with BBB Auto Line. Hopefully this'll get resolved soon, 'cuz I'm tired of just waiting around. I'll post an update here if anything significant happens.