This is a 27R AC Delco Professional 42 month battery dated 8/2018 and rated at 710 CCA that came in my 03 Sequoia. Truck started and ran fine yesterday. This morning, nothing. Couldn't even unlock with the remote. Battery tester couldn't even take a reading. After swapping in a battery from another car, I brought it inside to warm up. A few hours later I try testing it again and it shows 9.5 volts and a few CCA saying to charge and retest. So I do that, and now it's at over 13 volts and 650 CCA which is acceptable for a 3+ year old battery. I was expecting to see something like, bad cell. So why did it go completely dead in one day all by itself? I didn't leave anything on, but will know for sure when I start it tomorrow on the swapped battery.