It's not big enough in my opinion. The factory 12V battery is 33 Ah, and it's not even AGM or lithium. It's the Flooded Lead Acid (FLA) type. But that doesn't stop them from selling it at $500. Mine was going dead at random times for no apparent reason, sometimes in as little as 2 hours. I have done everything possible to address this problem, but that hasn't stopped me from being attacked constantly by trolls in this channel who deliberately misconstrue the facts.
It's not in the floor panel. There is a black plastic cover over it, tucked into the right fender well.
I found and consulted the 500+ page owner's manual. Less than helpful, but will attempt to read the whole thing anyway. Tells you where the jump location is under the hood, and bunches about how not to blind yourself and how complicated it is to put in a new battery, but nothing about where the battery is. I think they want you to go to the dealer for everything. I have read about problems with the 12V battery going dead. I have a charger on my lawn tractor that I plug in when not in use-didn't think the car MAY need it. Early days, I know, but is there room for a charger in/near the battery location?
I use a battery maintainer whenever possible. It has solved my problems for the most part, but occasionally the battery still goes dead. For this, I use a booster pack.
I have it permanently mounted under the hood, so I can plug it in whenever I park near an outlet. I'd had problems with alligator clips, so I removed them and connected it directly with ring terminals. The plug sticks out like a block heater cord, but not too far, so that the wind can flip it around until it breaks the wires inside.
In my case, I'd probably forget to unplug it. Having the plug in front might be less destructive when backing out of the garage.
I've done that a few times; the worst that happened was the cord was stretched out before it unplugged.
Honda always managed to include oil and transmission fluid changes, ditto for light bulbs, air filters and wiper blades IIRC. It’s a little dismaying Toyota omits such.
