powersurge wrote:The answer to this age old question of Leaf 12v batteries has 2 solutions... First, you do not need a L-ion battery, or AGM deep cycle. The 12v does not require any cold cranking power to start a big engine, so the stock one is adequate. If you want an upgrade, get the biggest that fits in the battery tray, or even get a bigger tray, and you can have a good, powerful, Lead Acid batter that can last 10 years, like my car batteries do.
Second, it is not the size or type of battery that is important. Battery problems so not happen suddenly, buy over time when we are not looking. My 3 year old battery is in NEW condition. I know this because I have installed a digital volt meter that tells me the battery voltage at all times when I drive. You can get one reasonable, and install it in the cigarette lighter, or hard wire it. When you see the battery voltage start going down, then you can investigate what your car is doing....
No large starting current draw, but sustained small currents so deep cycle is ideal. Maintenance free AGM is my choice for my "install it and forget it" approach. A high quality conventional battery might last 10 years in your climate, but not mine. OEM batteries in gasoline engine cars typically last 18 months (24 months maximum) here. I once had an aftermarket replacement battery fail after 9 months and the warranty replacement fail 6 months later before I started using AGM replacement batteries. The OEM Nissan batteries in the LEAFs actually do a little better because temperatures under the hood are lower. I got 29 months on the 2011 and 32 months on the 2015.
Don't depend upon a voltmeter plugged in to the power socket to give reliable measurements because the port is only active when the car is on.
The battery store where I buy most of my batteries quit selling lithium ion motorcycle batteries because they had too many failures. I will buy one for one of my motorcycles as a test once they have enough confidence to start selling them again.