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DEAD 12 v BATTERY.

Discussion in 'Gen 3 Prius Main Forum' started by ANCHORMAN, Jan 22, 2022.

  1. ANCHORMAN

    ANCHORMAN Junior Member

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    2015 V. I left my cb radio on for 2 days. Car seems dead. Brake pedal is stiff. No interior lights nothing. I hooked up a jump starter under the hood per manual…didn’t start nothing . I unhooked the 12 v battery and have a charger on it. When it’s charged is it ok to just reconnect the battery cables and hope it works?
     
  2. xliderider

    xliderider Senior Member

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    Depends, sounds like your battery is very dead. Also, if your battery is more than 4 years old, you're probably better getting a new battery.

    If you have a low Amp charger, it may not be able to charge a really dead battery, more so if it is one of those "smart chargers" or battery maintainer type chargers. By low amp, I mean anything less than 10 Amps or so.

    Posted via the PriusChat mobile app.
     
  3. ANCHORMAN

    ANCHORMAN Junior Member

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    Yeah. The battery is probably old. I’ve had the car 1.5 years. Have been charging several hours on a Sears charger at 10 amp. Not up to 100% yet. I have a new battery for it but not a original equip battery it’s a VMAX. MR-207-85. To install it I need to swap out the cable connectors and modify the bracket slightly…the reasons it’s not in yet. The biggest problem is this happened on the coldest day of the year in Jacksonville Florida it stayed in the low 40s today and I froze my butt off doing the little I did with it.

    But, it should be safe to try reconnecting the charged up battery?
     
  4. xliderider

    xliderider Senior Member

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    I'd wait a little bit after disconnecting it from the charger to let any hydrogen gas (very flammable/explosive) vent off before connecting it (spark hazard).


    Posted via the PriusChat mobile app.
     
    privilege likes this.
  5. ASRDogman

    ASRDogman Senior Member

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    10 amps is over twice what it should be. 4.5 amps is what Toyota says.
    How many hours has it been charging? 4 or 5 hours at 10 amps is probably ample.

    To connect, disconnect, ALWAYS make sure the charger is NOT connected to the AC outlet.
    Connect positive first, then ground. After charging, disconnect negative first, then positive.

    If you charged in a well venitlated area, you shouldn't have any problem with fumes.

    At 10 amps. I would unplug it, and wait about 10 minutes before touching the battery.
    That allows it to cool down some.

    Since you already have a new battery, it would probably be best to install it and not worry
    that the old battery could fail at the worst time, which usually happens. (y)

     
  6. Johnny Cakes

    Johnny Cakes Senior Member

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    Several things:

    * It is not uncommon for a jump starter not to be able to start the car if the car's battery is extremely drained, which is sounds like yours is.
    * Unhooked the battery to charge it? Are you saying that you took the battery out?
    * A smart charger is better than just throwing 10AMP at the battery
    * I'm not familiar with the battery you are thinking of putting in, but batteries designed for the Prius have vent tubes since they are located "inside" the car.

    Now for the important question: What is CB radio like nowadays? I remember it from the 70's but thought it was dead.

    And no sympathy for "coldest day of the year in Jacksonville Florida it stayed in the low 40s today and I froze my butt off " -- I'd love for the temp around here to hit the low 40s.
     
    Merkey likes this.
  7. ANCHORMAN

    ANCHORMAN Junior Member

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    Thanks much for the information and support. It worked the car is running and in normal mode. I will leave it in ready mode for a couple hours for the computers to get over what happened and will move the battery swap up on the list. Got a cb for a Prius cross country trip a couple years ago and one thing let to another and now have a base station and it’s like crack you can’t quit and spend lots of money! Lots of die hards here although I hear not as much in some parts of the country. It’s a fun hobby.
     
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  8. sam spade 2

    sam spade 2 Senior Member

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    Yes. If it really is charged up.
    I don't see why you might think otherwise ??
     
  9. sam spade 2

    sam spade 2 Senior Member

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    Totally unnecessary.
    And maybe counter-productive.
    Do you have a voltmeter ?
    No self respecting CB'er would be without one.
    KNJ 2919.....1965. :)
     
  10. ANCHORMAN

    ANCHORMAN Junior Member

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    Of course. Didn’t need it though, as soon as I connected the battery both auxiliary USB outlets I have in the rear of the V both lit up reading over 12 v. I’ll keep an eye on those
     
  11. rjparker

    rjparker Tu Humilde Sirviente

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    Better off driving the car for thirty minutes or doing nothing. Driving will readjust the fuel trims and ensure the hv battery gets a good charge. The hv battery does not get a good charge in a Ready "idle" mode. There is a lot of thermal cycling that occurs as the car sits in Ready mode, also not good for the engine. Finally if the car has a water pump fail while you are out of the vehicle, very bad things can happen.
     
    #11 rjparker, Jan 23, 2022
    Last edited: Jan 23, 2022
  12. ANCHORMAN

    ANCHORMAN Junior Member

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    OK I went for a drive looking good so far will keep an eye on the voltage for awhile.
     
  13. ASRDogman

    ASRDogman Senior Member

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    Hopefully, the 12v battery will be okay.

     
  14. sam spade 2

    sam spade 2 Senior Member

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    You do know that fully charged it should read about 12.8........and that 12.0 is half dead........right ??
    When looking only at resting voltage, tenths of a volt are important.