I might need another 12 volt battery... Sigh. The first one that came w/my used 5/2013 built Leaf bit the dust in Oct 2015, IIRC. Dealer replaced it for free under warranty. Replacement is a Nissan "84 month" flooded battery.
I drove my Leaf before I went on vacation, probably on Oct 26. Let's just say, when I returned home I've tried charging it w/my Optimate 4 it for (originally) good measure and stopped before I went to work, surprised that it wasn't finished. I returned home from work and measured the voltage. It was reading about 10.5 volts. Ugh. I checked that it isn't low on water so it's charging once again. I expect it won't finish or won't hold a charge.
When I try searching Pep Boys for a '13 Leaf battery, it only comes up with https://www.pepboys.com/optima-yellowtop-deep-cycle-car-battery-group-size-51/product/313430/2013/NISSAN-DATSUN/LEAF/AC%20MOTOR?quantity=1 (Part#: YELD51R | SKU: 313430): $238 installed. I tried digging a bit for a Bosch 51R battery on Pep Boy's site to no avail. I tried a few other locations nearby.
(In Dec 2018, from Pep Boys, I did get a Bosch group 51 non-R AGM battery to replace the old Optima Yellow Top in my former 06 Prius...)
Given Nissan's pro-rated replacement 12 volt warranty, I'd have to pay 50% of the battery cost + labor... or get a battery myself and DIY.
I tried Costco's site and it sends me to a special Costco section of Interstate Battery's site. It comes up with a item number 852210 51R for $77 but doesn't tell me if my or any Costco's have it in stock.