I am surprised that so many people are so worried about what battery to put into their Leafs... Seems like some will even chuck a perfectly good battery to get that "special" battery. I have been driving and fixing my own cars for 40 years, and can tell you that the need to get that "best" battery is over with the Leaf.
Let us reason that the biggest test of a car's battery has always been to supply those ever-popular "cold-cranking-amps" in the dead of winter. That is gone with the Leaf... No cranking. The only real drain on the battery are the accessories on the car - lights, radio, and the biggest, the a/c. If the Leaf has been designed correctly, it will recharge the 12v battery from the main batteries at an acceptable rate. The only real consumer issue is to maintain the battery fully charge all through the year. I have had my car batteries last 8-10 years on my CAR batteries, which test the power of the battery a lot more. Get a good, cheap battery from Costco or Walmart.
To keep your battery in top shape, I suggest the following:
Wire this solar battery charger to the car and place it with double sided sticky tape on the dashboard. It will keep the battery at 100% even after MONTHS of car non-use. I have 4 cars, and always get them to start.http://www.harborfreight.com/15-watt-so ... 68692.html
Another way to keep the battery charged is to connect a "Battery Tender" charger to the battery every few weeks.
Every 6 months, to keep your peace of mind that your battery is still "strong" and holds a good charge (e.g., your battery is still good), use the battery meter below. It will put an electrical load on the battery and tell you if the battery itself is "good". http://www.harborfreight.com/automotive ... -9193.html
Someday, after 6-8 years (or even 10 years in my experience), it will give your a "weak" reading, and then you go to Walmart or Costco and get another cheap battery.
This has worked for me over the years, but I would welcome any comments....