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12v battery ?? please help.

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by Javierz0509, Jul 14, 2017.

  1. Javierz0509

    Javierz0509 Member

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    Guys I am trying to kinda troubleshoot my 12v battery depending on what it said here first thing in the morning without turning on the car on ill take the battery out of the car and take it to get tested.

    well here is what's happening at night i usually arrive home with my traction battery charge up not all the way up but the normal, well in the mornings for the past couple of weeks I notice in the state of charge screen that when I put the car in ready and the engine turns on to warm up as I drive out the traction battery drains quickly could this be that my 12v battery is low in voltage ???

    2013 prius c with 100k
    I am the second owner and I don't know if the first one ever replaced it ( i doubt it )
     
  2. bisco

    bisco cookie crumbler

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    no. the traction battery drains because the car goes easy on the engine until it warms a bit.

    if you want to test your 12v, get a volt meter, or swing by an auto parts store for a freebie.

    a 2013 12v is likely fine, but worth testing, especially in florida.

    btw, there is no 'normal' on the hybrid battery charge indicator. as long as it's not below two bars, it's fine. it's just showing an approximate state of charge.
     
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  3. Javierz0509

    Javierz0509 Member

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    But if i take the car to the auto parts for test won't that give an off reading since the traction battery supply the 12v battery when low voltage ?
     
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  4. jerrymildred

    jerrymildred Senior Member

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    It's pretty common in hot weather for the traction battery to drop in a hurry with supporting the ICE, as Bisco said, along with the air conditioning load. But, if the 12V is failing, it's that much more load on the traction battery, so I think you should follow his suggestion and have it tested for peace of mind, if not for anything else.
     
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    If they test the car with the car off (and they should) there is no problems. The cheapest way to check is to just check the voltage with a multimeter, with the car off. This gives a rudimentary status feedback, depending on the voltage. 12.5 or higher, it's not bad. 12.2~12.5 it's getting into trouble. Less than that, you're in serious trouble.

    But for more in-depth testing DIY, you need something like Solar BA5 (google that), which is a new-generation load tester. It'll give you the measured Cranking Amps, and a verdict, what to do. The battery shops, or dealerships, have similar, pro-level testers.
     
  6. Javierz0509

    Javierz0509 Member

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    Ok I'll take the car to the auto part and have them check it the 12v battery, Ill keep ya posted.
     
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  7. Javierz0509

    Javierz0509 Member

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    Ok update the auto part that does free check up won't check it cause it's a hybrid but they told me to take it out and bring it to them to test.
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Try another place, they are incompetent. Or dealership but they might charge. Or start with a DIY cheap multimeter voltage check.

    I check ours occasionally with a Solar BA5, just need to hook up directly at the posts. No need to remove.
     
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  9. bisco

    bisco cookie crumbler

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    the inverter keeps your 12v charged all the time. if you measure it with the car in ready mode, you'll see around 14.4 volts.
    when you shut it off, a surface charge remains, giving you a false high reading.
    if you test it at home, it's best to let it sit overnight. the machine an autocrats store uses probably mitigates that issue by putting a load on it.
     
  10. Javierz0509

    Javierz0509 Member

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    My dad will bring his voltage meter and show me how to use it lol
     
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  11. bisco

    bisco cookie crumbler

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    that's what dads are for, unless mum is the mechanical one.;)
     
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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Once you're done with the car, you can check the condition of all the old batteries (AA or whatever) rattling around in the tool drawer. (y)

    Now you've got an answer, when someone asks what you want for your bday or Xmas.
     
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  13. Javierz0509

    Javierz0509 Member

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    Update.. my dad check the battery with his fluke meter and the battery read with 12.84 with car off and with car off light on 12.24 with car on ready 14. Something i forgot but was 14v something.
     
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  14. Javierz0509

    Javierz0509 Member

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    Oh yes i am going to ask for it lol
     
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  15. Mendel Leisk

    Mendel Leisk Senior Member

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    Sounds good. Solar BA5 or sim will give more in depth assessment, but 12.8, odds are it's fine.
     
  16. bisco

    bisco cookie crumbler

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    how long had the car been off for? if it went to 12.s w/ lights and stayed there, that's a bit low.
     
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  17. Javierz0509

    Javierz0509 Member

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    Yeah 12.24 with headlights and fog lights on, car was off.
     
  18. bisco

    bisco cookie crumbler

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    how long had the car been off when you measured 12.8?
     
  19. davids45

    davids45 Active Member

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    G'day javierz,

    If you've been a 'naughty boy' and Santa won't be coming :( , but if you have a few dollars to spare :) , you could check out a 4-in-1 cigarette lighter socket plug that, as well as having two USB charger sockets, will display in sequence (about 5 seconds per reading in a continuous cycle) your car's battery voltage, cabin temperature and USB amps out (when a device is plugged into the charger socket, otherwise '0.00A').

    For e-bay example: Portable Black 4 In 1 Dual USB Car Charger Adapter Voltage DC 5V 3.1A Tester
    There are plenty to pick from in a wide range of prices.

    I've one in my 'c' which unfortunately I can't read while driving because the accessory socket is out of sight of the driver. But it does show the 'off' voltage is about 12V and the 'on' voltage is just over 14V to tell me the 12V battery is fine, as is its charging by the car. And gives my passenger something else to read/watch as well as the map screen as we drive along.

    I've attached a photo of mine with two extendable micro-USB leads plugged in and showing the battery voltage with the car's 'Power' on.

    David S.
     

    Attached Files:

  20. Javierz0509

    Javierz0509 Member

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    Wow buying now, wouldn't hurt thanks