Worth it to keep that warranty up though.
It's not really needed. Nissan can't legally void the warranty for not having it done unless they can prove that not having it done caused damage some how (which is impossible, since it's just a report- it does absolutely nothing to the battery).
If you never changed your oil on a gas car and your engine blew up, it would be pretty easy to demonstrate that lack of maintenance caused the problem. They could void your warranty for not having the oil changed- which, by the way, you can have done anywhere you want (or done by yourself)- it's illegal for them to require you to get it serviced at the dealer to maintain a warranty.
But with the battery check, it has nothing to do with maintenance- it's just a data gathering tool for Nissan engineers and a way for the dealer to get you back into the service center every year so they can make some money and sell you $50 wiper blades and $30 tire rotations.
Get it done while it's free. After that, don't bother. The only real value is if you're curious to see how Nissan rates your treatment of the battery.