New battery but engine won't start

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by AnotherMNPriusOwner, Feb 14, 2021.

  1. AnotherMNPriusOwner

    AnotherMNPriusOwner New Member

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    Our 2015 Prius (56K miles) had a new battery installed a few weeks ago (after the original battery died). All seemed well until this past week when we discovered that the car wouldn't start. We'd press the button after depressing the brake pedal, hear a mechanical whirr noise but the engine wouldn't start. Check engine light came on. Also the triangle warning light came on at one point. The cabin lights would come on after pressing them, though they were shaky and dim.

    So yesterday I jumped it and it ran fine. I drove it for 5-10 minutes and then parked it in the driveway. Turned it off, then the car refused to start again.

    I should mention that it's been subzero temperatures here the past week.

    When the car died a couple of months ago, before the new battery install, the AAA mechanic who jumped it told us that we should drive it for at least 45 minutes after getting a jump to let the battery fully charge. Is this true? Is that why our Prius died again after I only drove it for 5-10 minutes after a jump yesterday?

    Now the car doesn't make any sounds after I press the start button/depress the brake. The cabin lights turn on but dimly. Neither of our key fobs works and one of those has a new battery.

    Any ideas as to what is going on? We haven't been driving it much. We both work from home, so we take it out maybe once a week. It is parked outside year-round. Thanks for any insight.
     
    #1 AnotherMNPriusOwner, Feb 14, 2021
  2. rjparker

    rjparker Tu Humilde Sirviente

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    Just gave this answer to another.

    Your battery loses voltage in extreme cold. When it warms the voltage goes back up. All modern cars draw power constantly but some top batteries maintain their voltage better. The problem is worse if you don't drive it everyday. When things are dim it is really discharged. The ideal solution is to put a battery maintainer on it overnight to ensure a full charge and keep the charger on it if it won't be driven for several days. Even with a "new" battery. Any battery can discharge overnight under some conditions like the rear hatch not completely closed.

     
    #2 rjparker, Feb 14, 2021
  3. TMR-JWAP

    TMR-JWAP Senior Member

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    If you live in a safe area, just jump the car again, leave it in ready condition and it will self charge the 12v battery in about 12-15 hours. The engine will start and stop as needed to keep the HV battery charged. The 12v battery in a prius charges very slowly when charged by the car. 45 minutes won't work. 5-10 minutes is guaranteed to be inadequate.
     
    #3 TMR-JWAP, Feb 14, 2021
  4. sam spade 2

    sam spade 2 Senior Member

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    Yes, a good idea.

    Very likely that your new battery has never been fully charged.
    They often come off the shelf at 50% or less and shops don't routinely check that.

    The onboard charging system will take a LONG time to make up that missing 50%........like maybe 10 hours of driving.

    So, you need to get your battery fully charged.
    And then figure out how to drive it at least a couple of hours a week OR get a battery tender connected to it for a few hours each week.

    It is also possible that your new battery has failed already.
    It does not happen often but it does happen occasionally.
     
    #4 sam spade 2, Feb 15, 2021
  5. kneeboard

    kneeboard New Member

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    My battery went out on my 2015 Prius last week at a Subway Rest. It took a jump from AAA and I got home. I charged it over-night with a 10 amp charger. At Autozone I took it out of the car and they tested it at 85% with a note it had to be replaced. I installed a new one $210 from Toyota Parts Dept. drove it home and charged it overnight. I have a portable battery jump unit that I carry in the car to make sure that took care of the problem. It has been working fine for 3 days so far, temps are in the 20's.
     
    #5 kneeboard, Feb 15, 2021
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  6. Grit

    Grit Senior Member

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    o_O
     
    #6 Grit, Feb 16, 2021
  7. sam spade 2

    sam spade 2 Senior Member

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    +1
    BUT.....if it was an automatic 10 amp charger, that should be fine.
    Most these days are.
    Except for that big red piece of CRAP from Harbor Freight.
     
    #7 sam spade 2, Feb 16, 2021
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  8. AnotherMNPriusOwner

    AnotherMNPriusOwner New Member

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    Thanks for all the advice and information.

    I bought a 2 amp slow charger and have had that connected under the hood since Friday evening. It's still showing less than 25% battery on the charger, but now the key fob works. So that is something. (Car still won't start, of course.)

    Regarding the suggestion to leave the Prius in Ready mode for 12+ hours after jumping it... we live a few blocks from a high-crime area of St. Paul and leaving a car on and unattended is technically illegal here. But since we work from home, maybe I could get away with trying that during the daytime when the motion-detecting camera and I are keeping a close eye on it.
     
    #8 AnotherMNPriusOwner, Feb 21, 2021
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