I just installed an Optima yellow top D51R in my 2015. A 10 mm deep socket fits the terminal clamps and hold down bolts. I turned the car off, opened the hood, disconnected and removed the old battery, used baking soda and water to clean battery tray and surrounding area, wire brushed terminals and posts of new battery, and then installed and connected the new battery. Power was disconnected for extended time because I was in no hurry and I let the battery tray dry before installing the new battery.
The trip odometers, miles/kWh, and elapsed time displays in the dash were cleared, but the information in the navigation system was retained. Radio presets, clock, recent routes, CarWings settings, etc. were all retained. Start/end times and days for charge timers were retained, but timers were turned off. Also, the auto up function of the driver window was disabled so I had to reactivate it by fully opening the window and then fully closing it and holding the switch in the close position for several seconds after the window was fully closed.
I started the car and used LEAF Spy Pro to check for DTCs. Four codes were present which were easily cleared. I drove around a bit and then charged the car overnight. There was no need to connect an external charger.
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015