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12 Volt Battery Low

Discussion in 'Prime Main Forum (2017-2022)' started by maiki, Mar 21, 2019.

  1. Mendel Leisk

    Mendel Leisk Senior Member

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    I think another time it was map lights. Or maybe the sneaky little light on the passenger side visor with mirror.

    I would argue the scenarios where it does shut down are outnumbered. Maybe even no-show, lol.
     
  2. Jay Lathrop

    Jay Lathrop New Member

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  3. bisco

    bisco cookie crumbler

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    good idea
     
  4. Classic Car Guy

    Classic Car Guy Active Member

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    My wife's 2018 12 volt battery died too. is that still under warranty? I'm trying to do a slow-charging externally and Ill see if it fires up tomorrow.
    PS. she has that extra 5 years maintenance warranty and I'm not sure if it covers it. The car is not even 6,000 miles.
     
  5. kenoarto

    kenoarto Senior Member

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    Only 3000 miles per year? How are you keeping the battery charged?

    Posted via the PriusChat mobile app.
     
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  6. Classic Car Guy

    Classic Car Guy Active Member

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    I know man. That's what I been telling my wife since that's her car and atleast drive it once a week.
    Well anyways I'm not sure if the warranty will cover that? In case not Ill have to get a battery for her. Any takes for battery replacement if in case?
     
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    3k a year is roughly what we’re doing too. Car’s on a CTEK 4.3 charger (with quick-connect installed) pretty much all the time. If you’re in a garage with 120 volt available that’s the way to go.
     
  8. Classic Car Guy

    Classic Car Guy Active Member

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    Okay great. With a stroke of luck, the car started after slow charging the 12 volt battery since 8 am this morning. so I let it idle on for 15 minutes while I was pumping air on all 4 tires. I took the car for an easy cruise and notice the hybrid battery was low so I let it build up by driving gradually for 22 minutes. as before I parked the hybrid battery is 7/8 full.
    I took off the 12 volts battery post again and tonight Ill slow charge it again,, and drive it again tomorrow for another 30 to 40 minutes till the hybrid battery is full. I only have 2 years of owning and fixing the 100k mile maintenance experience with these type of car since I bought my 07 prius last 2 years.
    So do you think that's a good idea that I didn't go all the way charging the hybrid battery right away so it wont shock it being the car hasn't been driven for maybe 3 months?
    Thanks....
     
  9. kenoarto

    kenoarto Senior Member

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    I bought a smart "Battery Tender" to care for my little 12v. Your big HV needs to be driven (idle in garage is fine, too) every week or two to keep the bars are half way (full bars is in indicator of a failing HV battery). Note to garageless: idling in street is an expensive moving violation.
    Posted via the PriusChat mobile app.
     
  10. Classic Car Guy

    Classic Car Guy Active Member

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    Is this the one youre talking about? Can I leave it on all the time?

    Battery Tender 0.75-Amp 12-Volt Car Battery Charger

    Item #1570621Model #021-0123
    • STAY CHARGED: Provides a full charge to your machine’s battery before switching to float mode to maintain proper voltage levels for safe, long term storage without overcharging

    • Spark proof during lead connection, reverse polarity protected and includes a 12-foot output cord and 5-year warranty

    • EASY TO USE: Low maintenance design to be quick and easy to use, our universal powersport vehicle charger and maintainer is compact
    [​IMG]
     
  11. Gokhan

    Gokhan Senior Member

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    Toyota replaces the 12 V battery for free while under warranty, even if the failure is due to neglect by the owner.

    However, know how to charge your battery and not to let it discharge: Don't sit in the car for more than a minute with the lights on and the ignition switch off or in the accessory mode. While you're sitting in the car, READY should always display on the MFD unless all lights and the audio are off. If you don't drive the car regularly, charge the traction (hybrid) battery and then leave the ignition switch on for several hours with READY displayed on the MFD in the EV mode with the car safely parked in the garage and without letting the traction battery drain and the ICE kick in.
     
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  12. Salamander_King

    Salamander_King Senior Member

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    Are you talking about a 2018 Prius Prime? It sounds like you have a regular Prius. Either way, you might learn a thing or two reading this very long thread on the 12v battery in PP.
    12v Battery Is Discharging, Re-Charge Now ! | PriusChat

    BTW, the battery tender you posted should work fine. My PP is currently driven only ~40miles once a week. I park my car outside and don't want the 12v hooked to the outlet all the time, so I installed a Bluetooth battery monitor to check on the resting voltage at the post every day. The app let me know to charge the 12v battery when the voltage drops to below 12.4v. I use a 4A smart charger from Victron to charge the 12v battery. This happens about every 3-4 weeks with only once a week driving I am doing now.

    Screenshot 2020-04-27 at 8.19.47 AM.png
     
  13. Hicksite

    Hicksite Member

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    Nice “B”! What year?
     
  14. Classic Car Guy

    Classic Car Guy Active Member

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    Okay . My wifes car is just a prius regular. She gotten too overboard on getting a real good gas mileage on the car till she starts worshiping and don't even want to "scratch the mileage"
    Ill probably just gonna hand that car to her for the last time so she'll be more aware on atleast starting it up once a week. I have 4 cars of my own and I spend atleast 2.5 hours a week just to start it up and all that. The 2007 prius is my everyday beater.
    The GB is a 67. what year do you have?
    [​IMG]
     
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  15. Hicksite

    Hicksite Member

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    We had a ‘76 for a while, and more recently a ‘67 with right hand drive. 67 was the best year for B’s in my opinion. Had a 2010 Prius for about 6 years and now have a 2020 Prime.
     
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  16. johnamerc

    johnamerc Junior Member

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    My 2018 Prime Premium had a dead 12V battery when delivery was attempted September 17th 2018. the 12 V died quite a few times and the dealer finally replaced it this past summer under warranty w/ around 47,000 miles. (only 21 months after original delivery. I did find out if I charged up the main battery the 12 Volt battery would start the car immediately after the charged was finished. If I was not near a charger starting was chancy. After calling roadside service on Toyota's nickel six times they may have decided it was a losing proposition for them not to replace the battery. (We have 24 months of free roadside service.) New battery is fine up here even in 2 degree mornings.

    Luckily have loads of free electricity up here in the Fingerlakes region of NY. Some as close as a1/3 mile from my office. My favorite is at a park on Cayuga Lake 1.5 miles away. I work on my laptop, walk or nap during the painfully long charging process. The Kona charges twice as fast even on J1772. No DC fast close by yet. Very nice free DC Fast charger at the welcome center on I 81 north coming into NY from PA. My son has an Ioniq EV and stops there coming back from trips south.

    2018 Prime Premium 55,918 miles 147.1 MPG lifetime per dashboard reading.

    considering a Kona EV as a next step or maybe Tesla Model 3 . . . sorry Toyota . . . after owning around seven Toyotas over the years . . . .

    Now if Toyota ever considers selling a pure EV in the US . . . who knows?
     
    #76 johnamerc, Jan 3, 2021
    Last edited: Jan 3, 2021
  17. pghyndman

    pghyndman Active Member

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    Yikes... MG (seriously though, yours looks sweet)!

    My '59/'60 MGA 1600 twin cam was a good looker, a so-so driver (decent but not outstanding gymkhana car... 289 TVR Grfiths would wipe my plate), but a nightmare to maintain. A positive ground 12v system consisting of two 6 volt batteries in series (Lucas: Prince of darkness) dual SU carbs which were beasts to sync, a distributor that could find moisture in a desert , cable release door "handles", side curtains in lieu of windows, a wooden bow for the convertible top, spoke knock-off wheels that constantly needed truing..... phewww. Romantic memories but a PITA to own!

    I had more fun and a lot less angst with my VW/Porsche kit-car (that was wayyyy back when I had a lot of hair and no belly)!


    29SSsmall.jpg
     
    #77 pghyndman, Jan 3, 2021
    Last edited: Jan 4, 2021
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  18. Classic Car Guy

    Classic Car Guy Active Member

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    Wow nice kit! They are always a blast to drive. Love the early years you can buy parts anywhere and USA is such as strong manufacturer of these kind of stuffs.
     
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  19. Mendel Leisk

    Mendel Leisk Senior Member

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    I would refuse deliver at time of purchase. Dealerships are slackers, don’t maintain the 12 volts. Having them demonstrate to you the 12 volt health with their electronic load tester is good for both parties. Good gizmo to have yourself btw.
     
  20. PT Guy

    PT Guy Senior Member

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    The 12v battery does not start the engine. The engine has no starter motor nor alternator. The traction battery, through one of the motor-generators starts the engine. The traction battery recharges the 12v battery. The 12v battery's job is to power the electronics that allow the car to go to "Ready."

    A replacement 12v battery is a Group 140R. O'Reilly and NAPA have them, or any other store that sells batteries made by DEKA/East Penn. I don't know of other American battery makers for this size.