12 V battery finally gives up the ghost

Discussion in 'Prius c Main Forum' started by davidc83, Apr 13, 2026.

  1. davidc83

    davidc83 Member

    Joined:
    Oct 14, 2015
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    Location:
    Scottsburg, Indiana
    Vehicle:
    2015 Prius c
    Model:
    Five
    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.
     
    bisco likes this.
  2. rjdriver

    rjdriver Active Member

    Joined:
    Apr 7, 2012
    411
    172
    0
    Location:
    Rhode Island
    Vehicle:
    2012 Prius c
    Model:
    Three
    I thought I did well to get almost 7 years from my OEM. Pretty sweet to make it close to 11. With Toyota discontinuing theirs, and me approaching the 7th year on its replacement. it's good to know there is a Die Hard out there as an option. As I recall, there weren't a lot of choices when I shopped around 7 years ago.
     
  3. VelvetFoot

    VelvetFoot Senior Member

    Joined:
    Sep 17, 2025
    1,334
    519
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    Location:
    New York State
    Vehicle:
    2026 Prius
    Model:
    LE
    11 years! In Indiana! I'm impressed!
     
  4. Kerrynzl

    Kerrynzl Member

    Joined:
    Nov 12, 2022
    56
    27
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    Location:
    New Zealand
    Vehicle:
    2016 Aqua
    Model:
    N/A
    That is a miracle?
    These batteries don't have much capacity and will go flat on standby reasonably quickly.
    My battery was new in January and I left the car in storage for 2 months while overseas. [I disconnect alarms before I do this]

    I asked the crowd running the car park to move it every 3 weeks or so to give the battery a "kick in the guts"
    But they didn't.............
    Anyway I returned last week to a flat battery and the carpark people were to frightened to jump start a hybrid [So I showed them]
    I've also been caught out being parked at the beach drinking coffee and listening to music and the battery goes flat
    So a jumper pack should be in the car's arsenal of tools.

    I have jump started an Aussie Falcon [4.0 24v EFI Barra engine] with an 18v 4ah Makita Li-ion battery and it worked great.
    But I'm a bit reluctant to shove 18v-21v into the Prius C electrics.
    Also the Prius will Self Start after a few seconds of being parallel connected so the Jumper needs to be diode protected from the Prius.


    I might make my own jumper pack as a DIY project and maybe post a "How-To" here if anybody is interested.
    I have piles of dead Makita Batteries and clones lying around [I have a tool addiction]