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Newbie battery question

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Martinf, Jul 7, 2024 at 3:45 PM.

  1. Martinf

    Martinf New Member

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    Location:
    Chelan, wa
    Vehicle:
    2008 Prius
    Model:
    SE
    I'm a subaru mechanic, but don't know much about prius. My daughter has a 2008 with a dead 12v from leaving a door ajar. Known good battery (I replaced it 3 months ago).

    My questions pertains to a jump start. I know where the pads are under the hood, so she can jump it. No problem there.

    If it were a subaru, I'd tell her to just go for a 30 min drive after the jump and she'd be good. But, what about the prius? If she's going in stop and go traffic, which she will have to, won't the engine be stopping and then need to restart, but the 12v battery won't have enough charge and she'll be stuck again?

    Or, if she just stays in the parking lot where she's getting jumped, will the engine keep running (after the jump) to charge the 12v battery?

    She doesn't have access to a trickle charger and there's no 120 v access out there in the parking lot and I'm across the state. And I doubt she could pull the 12v and bring it inside.

    Get my situation and the jist of my question? Thanks for any insight here!
    ~martin
     
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    If you run it in "B" mode (instead of Drive), the engine won't shut down at a stop so you can use that technique to keep the engine running to keep the 12V charged during the drive after a jump.

    Note that the engine may seem like it's stuttering because the computer is trying to shut it off but the parameters of B mode won't let it shut down.
     
  3. Brian1954

    Brian1954 Active Member

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    Location:
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    III
    The internal combustion engine does not need to be running to charge the 12v battery. The Prius does not have an alternator. The 12v battery is charged from the hybrid battery by the dc/dc conveter whenever the car is in ready mode and the car is in park or drive. But it will take many hours for the car to fully charge the 12v battery. It is best to fully charge the 12v battery by using a charger.
     
  4. bisco

    bisco cookie crumbler

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    if there is a safe place, she can leave the car 'ready' in park for about 8 hours and the battery should get a good charge.