freightliner jump starting question

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by gobby, Sep 24, 2019.

  1. gobby

    gobby Bobtail Member

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    May 23, 2019
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    oh nice!
    anyway of knowing which positive is for that starter? without having to climb underneath and track it back in the middle of the night? that`s the one I want to put my booster cables on.need all the power I have to get to that starter
    thanks for replying to my question mhyn!
     
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  3. gobby

    gobby Bobtail Member

    7
    3
    May 23, 2019
    0
    oh nice!
    anyway of knowing which positive is for that starter? without having to climb underneath and track it back in the middle of the night? that`s the one I want to put my booster cables on.need all the power I have to get to that starter
    thanks for replying to my question mhyn!

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    mhyn Thanks this.
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  5. mhyn

    mhyn Road Train Member

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    in your setup all positives are connected each other. you can put jumper cable on any red cable you see. the red cable that is connected to right inner battery goes to starter.
     
    gobby and AModelCat Thank this.
  6. mhyn

    mhyn Road Train Member

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    gobby there are no house batteries there. the red cable that goes down wired to starter. Second red cable that goes up wired to PNDB. I see you have 3rd red cable. That can be wired to jumper post.
     
    gobby Thanks this.
  7. gobby

    gobby Bobtail Member

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    May 23, 2019
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    thanks so much for this info!
     
  8. Freddy2times

    Freddy2times Light Load Member

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    Feb 12, 2019
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    Hooking up batteries in series the voltage adds up and amps stay the same.
    Parallel, voltage stays the same and the amps add up. Most systems are 12v (parallel) but there are 24v systems out there(series)
    I've personally never heard of 2 batteries dedicated to the cab and 2 for starting hooked up in parallel.
    In the end it takes between 500 and 1000 amps(depends on many things) to turn over the engine. Therefore you need a large reserve (4 batteries to supply enough amps to start) while running your alternator supplies the vehicle with power and charges the batteries. The reason it runs at 14v roughly and not 12v like a battery.
    Also some manufactures run 2 cables from the batteries, other only 1. That simply depends on sure guage(diameter). Thats a question of cost and design. Electrical large guage wires are expensive.
     
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  9. Lamianitsa

    Lamianitsa Bobtail Member

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    Oct 27, 2021
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    The power supply are providing a series of outputs. Though, through the wiring appears to be parallel. The two post, one ground and one voltage, will assist in kick starting the engine.

    The voltage supply (batteries) will drain each other, if one battery is weak; they will essentially only be as strong as their weakest link.

    Therefore, I believe it is a series setup current drops across exasperated batteries. Though main wires provide an appearance of a parallel output, which in turn, current in = current out.

    Confusing enough. Simply, wired to appear parallel, for truck and engine use but I believe is actually a series setup. Less power provided to internal cab and more power needed to start engine. All components must be off to jumpstart weak batteries.

    Best bet, is to contact freightliner directly.
     
  10. Goodysnap

    Goodysnap Road Train Member

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    You have seriously confused many and my head hurts from reading this........

    The typical 12Volt DC truck electrical system with 4 batteries is wired in parrallel not series.
     
    Oxbow and God prefers Diesels Thank this.
  11. feldsforever

    feldsforever Road Train Member

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    What does wired Parnell mean?
    Mine are like the picture above all in a square.
    I did find two negative post mounted on the frame,1) on the back four batteries. Just behind the driver side tank. This one I was able to trace back and see it directly connected to the negative in the box.
    2) a identical black wire with red paint mounted behind the passenger side steer tire. I traced this one to the top of the starter. It was not connected to the same bolt that connects the starter to the alternator.
    I have yet to find one positive jump post. I would love to thou
     
  12. xsetra

    xsetra Road Train Member

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    Wired in "parallel".
    All the positives hooked together. All the negatives/grounds hooked together to frame. That is the way trucks are wired. 12volt systems.

    "Series" wiring is hooking positive to negative to positive to negative in a series. This compounds the volts. Don't wire your truck batteries like this.

    The picture of batteries posted earlier, looks like the positive battery posts are all in the middle and the negative posts are on the outer perimeter. Hooked up in parallel.
    The positive circuit usually has 2 wires feeding the starter.
    The negative also has 2 wires grounding to starter and frame. My truck has more grounds than this.

    I can't explain where your posts might be mounted.
    Good luck
     
    Last edited: Jan 3, 2022
  13. feldsforever

    feldsforever Road Train Member

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    I have two batteries smoking. So jumping is out of the question.
     
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