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How to Start on Dead Prius Battery

Discussion in 'Gen 4 Prius Main Forum' started by PaulHeiser, May 18, 2023.

  1. PaulHeiser

    PaulHeiser New Member

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    JUMP STARTING A PRIUS BATTERY: THE STEPS
    Before you jump-start a Prius battery, you’ll want to make sure that your Toyota Prius and the assisting vehicle are parked with the engines off. Then, follow the steps below:


    1. [​IMG]

    2. Open your car’s hood and look under the fuse box cover. There, you’ll find the jump start terminal.
    3. Connect the red positive jumper cable to the positive terminal in your car.
    4. Connect the second red positive cable to the positive battery terminal on the assisting vehicle.
    5. Connect the black negative cable to the negative battery terminal on the other car.
    6. Secure the second negative clamp to the vehicle’s metal frame. The part of the frame you choose should be unpainted and immoveable.
    7. Start the engine on the assisting vehicle and allow it to run for five minutes.
    8. Turn the Prius power switch to “ON” and wait for a “Ready” indicator light before starting your Prius.
    9. Disconnect the jumper cables in the reverse order of how they were connected.
    Now you’ll need to know how to charge a Prius battery. Once the jumper cables are removed, allow your Prius to run for up to 10 minutes before shutting it off again. This allows the Prius battery to recharge and prevents the vehicle from failing to start again later on.
     
  2. PaulHeiser

    PaulHeiser New Member

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    I was getting a lot of report that you can't jumpstart a Prius on a dead hybrid battery. I saw this quote on a dealership website.

    Can anyone say this works or not?
     
  3. jdenenberg

    jdenenberg EE Professor

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    You can jump start the 12v battery, but if the HV battery is depleted, your Prius will not be able to start the engine. Charging a depleted HV battery requires a special charger that a dealer can access, but the HV battery can only get depleted if your engine cannot start (either due to mechanical problems or no gas) and you continually try to start the engine. Driving in EV mode when you run out of gas is not a good idea.

    JeffD
     
  4. PaulHeiser

    PaulHeiser New Member

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    "Open your car’s hood and look under the fuse box cover. There, you’ll find the jump start terminal."

    This isn't true then? Hmmm, dealership published that on their website.
     
  5. prius16

    prius16 Active Member

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    You're telling me that you got that DANGEROUS MORONIC STUPID IDIOT CR*P advice from a dealer website?
    If so, they must want to MEGA SCREW their customers, and sell them TWO NEW VEHICLES.

    YOU NEVER EVER EVER EVER have both vehicles running at the same time - ***NEVER***!
    With both vehicles running, the alternator(s)/12-volt-charging electronics FIGHT - often to the DEATH!!


    It's best to disconnect the jumper cable first, before trying to start the dead car.
    Next best is to TURN OFF the good car, THEN try to start the dead car.

    Or, imho, get a jump pack on Amazon. They have protection circuits in them, to prevent the dead/target vehicle from trying to charge the jump-pack batteries, or to fight the jump pack electronics.

    Or, get a jump pack, with a 12v dry cell, like the older Stanley jump packs, or the professional jump packs.

    Imho, on a Gen4, just jump the battery using the battery terminals.
    If your car blows up, tell me, send me the official police, court, and expert documentation, and I'll consider sending a condolence card.

    Wow, just wow.
    MORONS that are over SIX DECADES BEHIND in basic automotive knowledge.
    Wow, they must have great service advisors and top notch mechanics - NOT!
    And yes, even in the early 70's, there were warnings about having the two vehicles running at the same time, because of the possibility of alternator or electronic damage.

    Btw, on a Prius, turning the car on, starts the high voltage/traction battery charging the 12volt battery. The engine does not have to be running.

    As for any comments about new electronics/charging system, I'll get some Mustangs, Camaros, and Vettes that would love to have their running alternators blow the Prius' just turned-on electronics to the moon and back.
    Heck, I haven't even mentioned the trucks, with their mega alternators.


    You've got to ask yourself one question. Do I feel lucky? Well, do ya, punk? :)
    Code:
    https://www.youtube.com/watch?v=f5NJFNaL2Qg
    Dirty Harry - "Do You Feel Lucky?" Clip Warner Bros.
    
     
    #5 prius16, May 18, 2023
    Last edited: May 18, 2023
  6. prius16

    prius16 Active Member

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    Wow, just wow.
    The above seems to be the official STUPID advice from Toyota.
    My pony car and I are going to go around to all of the Toyota dealerships, and start blowing the crud out of Toyota electronics. If my car and I can't do it, then I could get super nasty, and get a vehicle with an older high output GM alternator. GM alternators have a very infamous history. For many decades.
     
  7. bisco

    bisco cookie crumbler

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    that is true for the generations with the 12v in the back. if you deplete the hybrid battery, you can have a dealer charge it, buy a prolong charger, or build one yourself
     
  8. jdenenberg

    jdenenberg EE Professor

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    Never, never use a Prius to jump another car. There is too much risk of expensive damage to the power electronics. You can jump your Prius from another car, but never attach the cables backwards as expensive bills will occur. As stated above having a jump battery is a good idea. It allows you to be a good Samaritan with little risk to your Prius.

    JeffD
     
  9. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    It's not a simple true/false. It's more complicated.

    If your Prius 12v battery dies, you will not be able to boot the computers and close the contactors that make the big hybrid battery do its thing, and its thing includes starting the gas engine.

    so... if your 12v battery is dead and your hybrid battery is NOT dead, then it is possible to jump the Prius and get it started.

    If the 12v battery is dead and your hybrid battery is ALSO dead, don't bother. None of this will work. Tow to dealer.
     
    Brian1954 likes this.
  10. FuelMiser

    FuelMiser Senior Member

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    Or, keep one of these in your "trunk" and get going in about a minute!

    NOCO Specs.png
     
  11. ChapmanF

    ChapmanF Senior Member

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    Reiterating Leadfoot's point, that will "get you going in about a minute' if your only problem is a discharged 12 volt battery.

    It will not do squat for you if the battery that's dead is the 200 volt one.
     
  12. bisco

    bisco cookie crumbler

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    i think the op is confused, but since he hasn't returned...
     
  13. PaulHeiser

    PaulHeiser New Member

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    I looked for what that dealership said, and there is no node under the relay/fuse box. But my hybrid battery wasn't dead after all. There was something else going on which I got resolved after all.

    However I did actually charge the 12v battery with jumper cables hooked up to my van while it was running, and no problems occurred. This is a 2017 Prius Four.

    Honestly never heard of the technicalities before in regard to the battery technologies here, so I don't advise anyone try this either. And I do have one of those jump packs, but mine wasn't charged right then.
     
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  14. bisco

    bisco cookie crumbler

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    when you say 'node', do you mean the 'jump start terminal' you mention in your first post?

    if so, it's probably because the battery is under the hood in gen4, and you don't need it. that would have been for gen2 and gen3
     
  15. rjparker

    rjparker Tu Humilde Sirviente

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    The basics are the 12v battery is not designed to and won't crank the engine on a hybrid. No matter how good it is.

    The hybrid high voltage battery does the engine cranking at a much higher speed under direction of computers initiated with power from the 12v battery. It has to do this at startup and perhaps hundreds of times while you are driving. So it has to be powerful and resilient. A hybrid battery can sit idle for months and even a year and still crank the engine. A 12v battery can not.

    As far as jump starting a drained 12v battery goes, Toyota does instruct how to do it from another car as you indicate. But this is dangerous if polarities are reversed even for a second. Normally reversed polarity will blow multiple fuses and fusible links, often resulting in a tow.

    If you get a 12v car to car jump right, everything will be ok. But its recommended to use a lithium jump pack because their charge can last a year or more and they have reverse polarity protection built in. Any roadside service will use a jump pack. As a side benefit you can use the jump pack for other motorists instead of risking your hybrid.
     
    #15 rjparker, May 23, 2023
    Last edited: May 23, 2023
  16. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Yay I get my own practice at this! Super psyched! ...Not!

    Another driver in my family who shall remain nameless decided to leave the car in accessory mode for long enough to matter and ran down the 12v battery before abandoning the car in the airport parking lot and flying halfway across the country.

    So tomorrow I get to go to the airport and jump the Prius, let it charge up so that [REDACTED] can drive home after the trip.
     
  17. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Just updating, the process worked fine. I used my ~20 year old AGM jump box on the underhood jump terminal, got the Prius into READY mode without drama, and then sat there for an hour while it charged its 12v battery.

    [REDACTED] had no difficulty on the drive home a few hours later.
     
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  18. ColoradoCrow

    ColoradoCrow Active Member

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    I did this once...in 1987 on a gasser car. Had to push it half a mile to the nearest "hill".to pop the clutch and get it to start up...in the summer heat in FL...... being eaten by mosquitoes...I learned a VERY valuable lesson that day. I never did it again. :eek: Had a buddy run out of gas once and his Dad got him a gas tank and made him walk the 2 miles back to his car....I learned from his lesson also. (y) Good times. Sorry you had to do that...