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Battery tender points

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by tak1313, Feb 14, 2022.

  1. tak1313

    tak1313 Member

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    Since my wife has been working from home since the start of the Covid thing, we don't use the Prius as much because that was her commuter car.

    I finally got around to deciding to attach a battery tender (Noco Genius2d), and thought there was a bolt for the eyelet right at the positive jump tab in the fuse box, but apparently that's the Gen2.

    I prefer NOT to connect/run it all the way in the back at the battery, so does anyone with a Gen3 actually have one mounted under the hood? If so, where do you bolt the positive terminal to? There are a lot of places to bolt the negative to.
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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  3. tak1313

    tak1313 Member

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    GREAT! Thanks a bunch!
     
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  4. sam spade 2

    sam spade 2 Senior Member

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    It really is best to connect a "quick connect" SAE battery connection pig-tail directly to the battery and bring it out in the trunk.

    A few weeks ago I wouldn't have said that but..........

    My old tender gave up the ghost and I got a new Battery Tender brand and connected it to my Ford Fusion at the jump points.
    I watched the voltage to be sure the new tender was working right.
    To my surprise, when it got to the point where it should have been at a constant "float" voltage, the voltage actually was dancing around a couple of tenths every second or so.
    When I connected it directly to the battery, it worked fine.

    That may not be a problem with other models of cars but I won't be taking the chance.
     
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    I’ve had no problems , with a (CTEK) quick connect at the jump point. But I can see that: the longer and more complex the connection, the greater the odds of something flaking out.
     
  6. tak1313

    tak1313 Member

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    That's interesting. From what I can find, it appears that the jump tab in the Prius runs directly to the positive of the battery (albeit through 1 fuse). Ground is, well, ground. But this observation is based on wiring diagrams others have posted in PC (I don't have access to the wiring diagrams myself).

    PERHAPS, the Fusion's jump point goes through some circuitry? Of course, I haven't looked in to the gauge/length of wiring between the jump point and the battery, but I could see how the resistance of the wiring could cause issues via voltage drop on how the tender perceives the actual voltage at the battery terminal. For JUMPING purposes, any mild voltage drop wouldn't matter - unless using a new fangled lithium pack and the actual battery voltage is borderline so the jump pack doesn't sense the battery correctly. But many jump pack now days have "boost" mode that bypasses the sensing (at the risk of bypassing safety features - such as checking for reverse polarity).
     
    #6 tak1313, Feb 16, 2022
    Last edited: Feb 16, 2022
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  7. sam spade 2

    sam spade 2 Senior Member

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    Have you actually watched the voltage of the charger while it is doing it's thing......with various beginning states of charge ?
    I'm not suggestion that anything strange IS happening but the absence of any problems that you know about does not mean that it is operating right.......necessarily.
     
  8. sam spade 2

    sam spade 2 Senior Member

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    Not "through" any circuitry but there does seem to be smaller "sensor" wires connected to both battery posts.
    I assume that is what is reacting to the charger.
    Or causing the charger to react, depending on your point of view.