I bought my 2015 Prius C level 2, new in October 2015. I had never had to replace the 12 v battery as it never failed to 'ready' mode the Prius. Starting this past Friday (3 days ago), I had to turn the key 2 times to get in 'ready' mode. I thought it was weird but the rest of the day it operated fine. Saturday, it took me 4 times to turn the key before 'ready' mode and I went ah oh. Yesterday (Sunday), it took me 6 turns before 'ready' mode. All the days, after it finally got to 'ready' mode and I did my errands (takes me 20 minutes to get to town), the car turned on ok. I have a solar battery tender with odbt2 connector so I hooked it up yesterday afternoon after I got back home. This morning, I had to go to a Dr appointment, unhooked the tender and 'ready' mode was first turn. When done with dr, got in the car and 'ready' mode was first turn. drove around the town to do another appointment (20mph or less), got done with appointment and boom, no 'ready mode'. Took me 12 turns of the key before it went to 'ready' mode. Bit the bullet and for $260 got a replacement 12v. A diehard S34B20R battery (perfect fit). It has 340 CCA and 425 CA. By the way, Toyota no longer has that battery on their websiet and 2 dealerships in 2 different cities told me (I called them) Toyota discontinued the S34B20$ battery, only 3r party available now. Put the new battery in and all is well. I cant complain though, I got almost 11 years out of that OEM battery. The DIehard battery has a 4 year warranty.
