My 2011 Leaf is now 11 years old (bravo!) and the 12v accessory battery that was replaced under warranty in 2013 is now 9 years old (wow!). It says it's an 84-month battery, which equates to 7 years, so getting 9 years out of a battery is phenomenal. Question is, should I be looking for another great battery (read: one with a long warranty) or will any standard battery do? Is there any reason to go with an AGM battery like an Optima? I mean, we aren't relying on CCAs here to crank over an ICE in the freezing cold. What are the best properties to look for in a replacement battery for a LEAF?