Jump-starting

Discussion in 'LR4' started by Frank8, May 7, 2019.

  1. Frank8

    Frank8 Full Access Member

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    When jump-starting, according to manual one shouldn’t but the negative clamp from the donor directly on the negative battery terminal but use the vehicle grounding post.

    Is there a real reason for this? Why would it make electrical difference?

    My manual shows battery on driver’s side and ground post on passenger’s, but the battery is on the passenger side.

    I can’t find a grounding post.
     
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  2. cperez

    cperez Full Access Member

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    The negative terminal on the battery connects to a grounding post via a short thick black cable. However, that grounding post, though very close to the battery, is inaccessible to any normal sized clamp. I connected a battery maintainer to the red terminal and clamped the black lead to a screw just forward of the fuse box at the bottom of the battery tray. It seemed like it was grounded to the chassis and the maintainer didn't throw a fault that it was incorrectly connected.

    I have wondered the same thing...where do you ground the black lead when jumping? Do you peel the jumper cables apart so that they reach across the width of the engine bay?
     
  3. avslash

    avslash Full Access Member

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    Not saying it is correct, but I have jumped, and been jumped by connecting directly to the negative post on the battery, and seem to have suffered no ill effects.

    Electrically, the only difference I could see some possible effect on the BMS sensor as the jumper would attach on different sides of it depending on if you use the inaccessible grounding stud, or the battery post itself. Otherwise, the factory ground strap is a 10ish inch long cable routed directly to the grounding stud.

    Ground is ground, right?
     
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  4. Mcb14230

    Mcb14230 Full Access Member

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    I just went thru this on Monday, with a dead battery at the coast. No warning ever. there was no unpainted ground to use so i used the negative terminal on the battery. No issues to report whatsoever.
     
  5. Cthehentz

    Cthehentz Member

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    I just carry a small jump box for such occasions, Holmes it up and jumped the LR4 without issue.
     
  6. Frank8

    Frank8 Full Access Member

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    Thanks guys. I carry a Micro-start and was concerned because of what the manual says My battery is getting tired. Got a replacement scheduled in a week.

    Appreciate the help!
     
  7. ktm525

    ktm525 Full Access Member

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    Not connecting to the negative is a safety thing so escaping hydrogen gas off the battery does not ignite in the event of a spark. Never seen it happen though and I have boosted 100s of vehicles.
     
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  8. gumbedamit

    gumbedamit Member

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    You are correct, gases from the battery can be ignited from a spark connecting the cable to the battery, this is true for all cars. Yes, I've seen batteries explode.
     
  9. gsxr

    gsxr Full Access Member

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    Correct. This is also why the last connection made is supposed to be at a grounding point that is not the battery, so any spark will be some distance away from the battery.

    :albertein
     
  10. Mcb14230

    Mcb14230 Full Access Member

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    AGM batteries do not off gas as they are sealed which would negate the need to find a non-painted ground
     

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