Dead battery? Unsure- Please help!

Discussion in 'Gen 2 Prius Technical Discussion' started by Lutiebelle, Mar 31, 2019.

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  1. Lutiebelle

    Lutiebelle New Member

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    Vehicle:
    2007 Prius
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    Hi! I am.. not smart with cars- can anyone help me with what's wrong with my 2007 prius?

    Earlier today I drove to work, and within the 5 hours I was gone, the battery somehow died.

    All the warning lights flashed on a couple times, my fiancee tried to start the car a few more times, and everything went dead. There was very faint light on the 'check engine' light, and the park button & mirror lights were very dimly lit.

    I was parked on a side street, so I came back later when less people were there to attempt jumping it. We hooked it up following a YouTube video on the spot. We used the terminal under the hood on the right side of the Prius. We originally tried connecting the red cable to the screw, before connecting it to the metal plate.. but we also had it grounded to a bolt nearby. On her car, we had tried it connected to her battery on both ends, and grounded a different time. Still no power. 100% dead. We let them sit hooked up together off & on for almost an hour.

    I read in one place that the size of my jumper cable clamps might be the problem? So I bought a new size clamp to try again tomorrow since itll be warmer & the clamps barely held on before.

    So I guess this is a two part question-

    What did we do wrong /why wouldnt it start when we attempted to jump it?
    &
    Why would it have died in the first place?

    The last time it went dead was a super super cold -30°F night here in Wisconsin. :/ It did snow today, but it was only about 20°F at the lowest.


    Additionally, I was recently let go from a job, & have very little money. Should I look into towing it? Going to a mechanic? I've never done this before- thank you in advancs!!
     
    #1 Lutiebelle, Mar 31, 2019
  2. bisco

    bisco cookie crumbler

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    welcome!
    the 12 volt batteries very small and weak. once it dies the first time (from age or leaving a light on) it never fully recovers.
    sounds like yours is toast. how old is it? if there is an internal short, it can prevent the jump battery from being effective.
    shut the donor car off, connect the cables to your car, positive to the jump point (make sure the clamp has metal side on the metal side of the jump point, the other side of the jump point is plastic.) negative to a clean ground point under the hood. nut, bolt, etc.

    connect the other end to the battery of the donor car, positive first, then negative.

    then try to start your car, the cable size doesn't matter on a prius. if it won't start, you're gonna have to climb in the back and open the hatch from the inside. (see your owners manual) take a flashlight with you.
    then try again directly to your battery (under the hatch floor, rear right.
    if no luck again, disconnect the cables from your battery and hook the jumpers to your cables, that takes the bad battery out of the circuit.
    you will probably need to buy a new battery at an auto parts store (shop around for best price) and install it.
    but if it is fairly new, a recharge may solve the problem.

    all the best!(y)
     
    #2 bisco, Mar 31, 2019
    SFO and Lutiebelle like this.
  3. edthefox5

    edthefox5 Senior Member

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    Yours is the most posted about subject on this forum for years. The mystery's of the 12 volt battery. Since there is no starter motor in a Prius you never get any warning the 12 volt battery is getting tired. On a regular car you can tell as the starter motor starts acting up.

    The fact that it had already went dead on you is the main issue. Unless the battery was then reconditioned by using an anti suphating battery charger like the one linked below (mine) and then continued to watch and then maintenance charged monthly usually results in you getting stranded.
    Tiny little battery.

    Bad news is when it dies especially if an interior light was left on which is very easy to do it sometimes it gets so stone dead it will pull huge initial current when the jumper cables are hooked up. And the donor charging car will be able to deliver huge current. No current limiting going on there. That huge current draw is not good it sometimes damages the cars 12 volt buss resulting in inverter replacement. But usually will just blow alot of fuses if your lucky.

    That 12 volt battery is dead jim. Replace it don't bother charging it.

    I would never ever under any circumstances jump start a Prius. On this site for the last 12 years I have seen way too may of them seriously damaged doing that. If it happened to me I would have it towed home and then put on a charger/re-conditioner which is current limited.

    Owning a Prius is the main reason I have AAA.


     
    #3 edthefox5, Apr 1, 2019
    Last edited: Apr 1, 2019
  4. jerrymildred

    jerrymildred Senior Member

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    Not mentioned yet is that some cheap jumper cables only have an electrical connection on one side of the jaws. The other side is just a plastic clamp. The jump point in your Prius is only metal on one side as well. Guess what happens if you connect the metal side of the jumper cable to the plastic side of the positive jump point in the car. Yup! Nuthin'. Take a look at your jumper cable to see if that's what could have happened.

    As said before, you probably need a new 12V battery, but it should still start with a jump.
     
    #4 jerrymildred, Apr 1, 2019
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