Jumping 12V Battery direct from Battery

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Chodronish, Jul 11, 2020.

  1. Chodronish

    Chodronish Member

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    Apologies if this has been addressed in another threat, but I can't find it if it is. My 2008 Prius is pulled into the garage and the battery appears to be dead. How can I jump it from the battery in back? No better than to use my other Prius to jump it from the front (2007 is also in garage next to it), so I can get my stepson to come over and do it if I know how.

    Also, no hurry, so feel free to post even if it's been awhile since I asked. We do not need two cars at the same time these days with both of us working from home during the pandemic, which is likely why the battery ran down in the first place on the one that gets driven less, as well as that my wife tends to leave the key fob in the car which I've heard drains the battery.
     
    #1 Chodronish, Jul 11, 2020
    Last edited: Jul 11, 2020
  2. SFO

    SFO Senior Member

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    When was the 12v battery last changed, and how many hours per week is the vehicle driven?

    If the two (2) vehicles are side by side, use the jump points under the hood instead of tearing the back apart to open the rear hatch.
     
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  3. Chodronish

    Chodronish Member

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    Thanks for your response @SFO. I've always read that a Prius should not jump another car, even a Prius. The battery was new in 2017. The car is driven less than 2 hours a week, just for a couple of short trips.
     
  4. SFO

    SFO Senior Member

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    You need 12 volts to start the 'computer' in the non-running vehicle, be it a "portable jump pack" or from a 12v battery on a 'non-running' vehicle, once the computer has 12v, the vehicles engine will turn over and be started by the HV battery.

    Make the connection from a 12v power source using jumper cables, "ready" the non running vehicle without pressing the gas pedal, then disconnect the jumper cables before the jumped vehicle starts the engine in 7-10 seconds.

    Do you have a trickle charger you could charge the low 12v battery with?
     
    #4 SFO, Jul 11, 2020
    Last edited: Jul 11, 2020
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  5. Chodronish

    Chodronish Member

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    @SFO I do not have a trickle charger. I wonder if I should just get one? These vehicles are only being driven a little bit here and there, though the 2007 is driven more than the 2008, which may change once the 2008 gets detailed!
     
  6. bisco

    bisco cookie crumbler

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    yes, get an agm battery maintainer. cheap insurance.
     
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  7. Chodronish

    Chodronish Member

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    Thank you @bisco. I'll do that. Do you have any suggested source for one or brand?
     
  8. bisco

    bisco cookie crumbler

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    ctek is good, schumacher, or search here, lots of recommendations. an inexpensive one from amazon is fine, just check google for reviews.
     
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  9. Mendel Leisk

    Mendel Leisk Senior Member

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    A jump start will just get you rolling. I would only use that as a stop-gap, say for completely emergency need, or (preferably) to get you to a store with suitable 12 volt replacement battery for sale (phone ahead, confirm stock), and/or aforementioned charger.

    Look for a smarrt charger, 3.5 amps rating max (max spec'd in second gen Owner's Manual). You should be ok charging with the battery in the car (if you go that route). Just be very careful not to reverse connections, with the charger, jump start cables, whatever.

    Good rule of thumb with jump start cables: Start with positive cable first, get BOTH ends connected, done and dusted. THEN connect the negative cable, donor car first, dead car last. With dead car it's preferable to connect to ground, not directly to neg battery post, to avoid a spark in vicinity of battery (due to possibliity of battery venting hydrogen). I think in practice, in particular with AGM batteries, that risk is VERY remote.

    Just for giggles blow across the top of battery, just before making connection directly to post, if you go that route.

    Also, if you have a pair of safety glasses, and/or face shield, good time to use them.
     
    #9 Mendel Leisk, Jul 11, 2020
    Last edited: Jul 11, 2020
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  10. Chodronish

    Chodronish Member

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    Search "here"? No link.
     
  11. bisco

    bisco cookie crumbler

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    sorry, i meant the search feature. tons of threads on chargers and maintainers, or in posts regarding 12v problems.
     
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  12. bisco

    bisco cookie crumbler

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    first hit on amazon is the noco genius one. 24 bucks, cant go wrong. if you prefer more sophisticated, with more features and flexibility, or something that can charge faster as in @Mendel Leisk recommendation above, even better.
     
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  13. Chodronish

    Chodronish Member

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    Thanks for the advice @Mendel Leisk. I appreciate the directions for jumping. I'm going to order or purchase (from Autozone or somewhere?) the agm battery maintainer suggested. I am dumb as a box of rocks when it comes to stuff like this, so I want to make sure I get the right things and do it correctly so I don't cause any damage. I would appreciate any specific recommendations about what to purchase.
     
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  14. Chodronish

    Chodronish Member

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  15. sam spade 2

    sam spade 2 Senior Member

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    In his situation, he NEEDS a small smart tender type battery charger/maintainer......to help keep this from happening again.
    Hopefully the battery will come back with that kind of charger too.
    He does NOT need a "trickle charger".

    Even at just 3 years old, it sounds like the battery has had a hard life and might need to be replaced.......and then put on a tender.
     
  16. jzchen

    jzchen Senior Member

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  17. sam spade 2

    sam spade 2 Senior Member

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    Might be a good unit.....as long as you don't put too much faith in that "reconditioning" claim.

    Battery Tender is the brand most often recommended.
     
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  18. Mendel Leisk

    Mendel Leisk Senior Member

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    I'm using a CTEK 4.3 charger, a little high amp rating though 4.3 amps. CTEK 3300 *3.3 amps) might be good pick. I've one of those as well, my back up charger, lol. The mode button is getting a bit flakey on it though. The price for CTEK's has been going up a lot though. I got my 4.3 for around $80~90 CDN IIRC. Now I see it's around $150??
     
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  19. jzchen

    jzchen Senior Member

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    If the first BMW Deltran unit wasn't DOA for me, or I figured it out before the 2 year warranty was up, I'd probably be singing their praises as well. (I believe Deltran is the company name and Battery Tender is the model line). I did notice that they tend to be a little low on the amperage rating for my liking. The Schumacher units I have a ton of are 1.5 A. I think 2 A is also decent, but 4 A is good for charging especially when you're faced with a dead/very drained battery.

    Just in case the OP isn't aware the original Toyota battery has a label saying 4.2 A max, meaning rating of the charger used.

    moto g(7) power ?
     
  20. Chodronish

    Chodronish Member

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    @jzchen Is the Duracell charger at Costco a "smart" charger that keeps you from making mistakes or causing damage?
     
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