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Thread: proper use of jumper cables

  1. #11
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    I just helped a stranded lady with a jump a couple of days ago. Often the biggest problem is others who want to help. She did her car's end of the connection and I did mine. I waited for her to complete the connection on her end and then finished the ground/negative connection on my truck. And I quickly disconnected the ground on my truck it when her car started. But it does not always work out that neatly.

    But this discussion makes me wonder if it would be a good idea to break the jumper cables in half and install a connector there. Pull it apart before connecting and pull it apart again before disconnecting. But where to get a connector with a high enough current rating? I thought of a stage pin connector, but they are rated at 20 Amps and perhaps 30 or 50. I don't think that would be enough. I've seen a starter motor hard pin a 500 Amp meter so I probably need several hundred Amps. And is this even a good idea?
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

  2. #12
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    It's not likely that a "good" battery (fully charged) is going to generate much Hydrogen gas during a jump.

    But the "bad battery very may well once the engine starts and charging is in full swing.

    So,

    I always disconnect the Ground lead from the good battery first, Even then only after giving a good "blow" over the top of the battery to dissipate any gassing, and possible arc ignition.

    Then I disconnect the Positive clamp at the good battery and lay the cable clamps on the ground, well separated.
    Then, I return to the Now running, disabled vehicle, and disconnect the clamps indiscriminately.
    It can't spark!

    YMMV, but that works for me.

  3. #13
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    When working with wet cells,car and equipment batteries remember to ground yourself out too.Static discharge off your body is enough to cause major problems

    https://www.sciencedirect.com/scienc...0438869390070N
    I just need one more tool,just one!

  4. #14

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    I consider the chances of an hydrogen explosion from a modern battery are very slim. I always hook up battery to battery.

    The only thing on modern cars I've been told is to turn the headlights on the dead one before jumpering, to prevent a current inrush that could cook the computers.

  5. #15
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    The only thing I do that I haven't seen mentioned yet (unless I missed it) , is I always clip one end of the jumper cable's to the jacketing of the cables themself. Cant get a short that way, they can never touch. Other than that, I always touch the ground first, not to say that, that is the way it should be done but it's what I was taught. It has always made sense to me for the purpose of not accidentally making yourself the shortest path of least resistance. I've always done ground then hot on the receiving batt, then ground hot on the live batt, reverse and drive away. I have been cautioned more times then I can count about jumping from and to cars with tons of computer controls, especially removing a battery from a running "newer" vehicle. Something about the voltage from the alternator spiking and frying stuff because it lacks a signal voltage? I am still interested in concrete evidence related to that situation.
    My recommendation?

    No matter what I tell you, get a second opinion.

  6. #16
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    Quote Originally Posted by Paul Alciatore View Post
    But this discussion makes me wonder if it would be a good idea to break the jumper cables in half and install a connector there. Pull it apart before connecting and pull it apart again before disconnecting. But where to get a connector with a high enough current rating? I thought of a stage pin connector, but they are rated at 20 Amps and perhaps 30 or 50. I don't think that would be enough. I've seen a starter motor hard pin a 500 Amp meter so I probably need several hundred Amps. And is this even a good idea?
    Many tow trucks have a set of jumpers with Powerpole connectors on one end. They can just plug them in to the bumper or body of the truck instead of having to connect to the battery each time. They go up to at least 350 amp. Scroll down for the 350 amp connectors on this site. I have some in lower amp ratings to be able to disconnect power to take cabs off tractors etc.

    I've had 3 batteries explode. One was at a friends gas station. The battery was charging just below a receptacle and his plug was defective. When I tried to unplug the charger the battery blew up.

    The second was when I was buying a tractor trailer. The batteries were frozen and the dealer had one of those high amp boosters. The name of which escapes me. When I connected it to the batteries they exploded and acid went in my eyes and face. Luckily I had gloves and heavy clothes on. I threw snow on my face and eyes which were burning.

    The third was after work me and one of my workers were changing the oil on a tandem dump truck. I was underneath looking up putting the drain plug back in the pan. He was up top going to start putting the oil back in. We had one of those metal oil cans that had a long metal spout. He put the spout in the metal valve cover, then set the can down on the battery positive post. The explosion blew him off the fender and acid came raining down on me underneath. Good times.
    Last edited by Ridgerunner; 09-14-2018 at 08:40 AM.

  7. #17
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    .....
    Last edited by Picoprecision; 09-14-2018 at 09:55 PM.

  8. #18
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    I always go right to the battery. Only had one explode ever.
    Andy

  9. #19
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    Clovis CA USA
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    I have use same way for over 40 years
    (1) positive terminal on live battery, (2) positive on dead battery, (3) negative (ground) on live battery, and (4) ground connection on the engine block on dead car.

    It the safer way never had any explosions

    Dave


    Quote Originally Posted by aostling View Post
    I had to give a jump start to a neighbor with a dead battery. In the old days, I would have just hooked up the cables without giving much thought to the proper sequence of attachment -- that always worked. But now we are instructed to hook up in four steps: (1) positive terminal on live battery, (2) positive on dead battery, (3) negative (ground) on live battery, and (4) ground connection on the engine block on dead car.

    It was very difficult to find a bare bolt anywhere -- plastic obscured virtually the whole top of the engine. I attached the cable at the best place I could find. No dice. So I completed the job by using the ground terminal on the dead battery. The instructions had me thinking I was risking an explosion, but it worked.

    What would you have done?

  10. #20
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    May 2006
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    Quote Originally Posted by Tony907 View Post
    The only thing I do that I haven't seen mentioned yet (unless I missed it) , is I always clip one end of the jumper cable's to the jacketing of the cables themself. Cant get a short that way, they can never touch. Other than that, I always touch the ground first, not to say that, that is the way it should be done but it's what I was taught. It has always made sense to me for the purpose of not accidentally making yourself the shortest path of least resistance. I've always done ground then hot on the receiving batt, then ground hot on the live batt, reverse and drive away. I have been cautioned more times then I can count about jumping from and to cars with tons of computer controls, especially removing a battery from a running "newer" vehicle. Something about the voltage from the alternator spiking and frying stuff because it lacks a signal voltage? I am still interested in concrete evidence related to that situation.

    I have to keep that in mind about clipping the end to the jacketing - makes sense - I always just look at the other ends and make sure their apart,

    I usually always do negative last and i'll tell you why, it eliminates the chance of bumping the positive on something negative, something that can happen if not careful but a problem that is almost eliminated with ground last,

    when removing a battery from a car I do the opposite - I do negative first, this eliminates the chance of your wrench from the positive contacting a car body "active negative" if you attempt positive first you have at least two 180 degree places that could pose a threat,

    installation of a car battery is reverse, do your positive first - then your negative last...

    also - keep this in mind when jumping, this is actually pretty critical and something that can catch you off guard,

    when jumping battery to battery and even if your using the far away negative of a car body for a ground you still usually have to use the positive on the battery itself - first off and foremost is make sure you have a solid connection at the battery being charged - easier said then done as most people drive around with a half inch of green battery fungus growing from their terminals,,,

    secondly - no matter how sure you think you are about that connection, stand back - in fact stand way back after the cables have been connected for awhile and the battery has been charging and you then tell the person in the car to "go for it" the reason being is this is the biggest amperage draw that connection will see so if the connection is not good and it "ops out" it WILL cause an arc, an arc that will happen at maximum off-gassing, moral of the story is you may think you've done everything right but the devils in the details and you could still get an acid bath if your not careful...

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