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jump starting 24 volt equipment

Discussion in 'General Industry Questions' started by cat320, Sep 1, 2005.

  1. cat320

    cat320 Charter Member

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    I was just thinking of this and never had to but what if you had to jump a piece of equipment that was 24 volt in the field and all you had was your truck and cables. 12 volt to 24 volt does not mix.
     
  2. littledenny

    littledenny Well-Known Member

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    Interesting thought. Guess from my military experience, I've never had to jump off a 24 volt system when I didn't have another 24 volt vehicle around. We just hauled out the heavy cables with the huge plugs, and just plugged grill to grill with them.

    Suppose you could hook the 12 volt cables across just one battery, or two batteries what were plugged in parallel on a four battry system, and add the boost from the 12 volt system into half of the 24 volt ststem. Suppose you could even use two sets of cables and jump to both 12 volt sides of the 24 volt system, but that would tricky for someone who doesn't fully understand series-parallel wiring.

    Be interesting to see if anyone has actually had to do this. Might even be fun to stand back and watch all the loudish poppin undt spitzensparken.
     
  3. digger242j

    digger242j Administrator

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    :waving I have, but only a hundred times or so.

    You're right about going to just one battery. What I've done is to go to one battery, and hooked the cables up, positive to positive and negative to negative. I let that battery charge up a bit off the "jumping" vehicle, and then switch the cables to the second battery, and let it charge a bit. If the "dead" 24 volt system isn't too dead, that'll work pretty well.

    Sometimes you'll have a 24 volt system that's made up of four 6-volt batteries. In that case, you charge the first pair, and then the second pair, as if each pair was a single 12-volt battery (which, in effect, it is).

    I've never tried using two sets of cables and jumping both batteries at once. I've never even *wanted* to try that.

    You should really be familiar with that concept before you start hooking up the cables at all...
     
  4. Dwan Hall

    Dwan Hall Senior Member

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    DO NOT USE 2 sets of cables to jump both batteries at once as this will short out both of the batteries in the 24 volt system. this could cause the batteries to explode
    unless you use 2 different source systems which have no comon connections.
     
    Last edited: Sep 1, 2005
  5. littledenny

    littledenny Well-Known Member

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    Didn't know that - Thanks.
     
  6. fixou812

    fixou812 Senior Member

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    You can charge or jump a 12 or 24 with a portable dc welding machine
    you just need to know how to do it and have a suitable machine
    don't use this technique if you have a dead cell
    your thoughts on this?
     
  7. grandpa

    grandpa Senior Member

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    And when placing or removing cable's ,, never ever put your face over that battery!!!!!!!!!!!!!!!!!!
     
  8. Construct'O

    Construct'O Senior Member

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    With so many machines now having computers, a person needs to be careful also not to smoke the computer trying to jump start a machine.
     
  9. catman13

    catman13 Well-Known Member

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    i do it like Digger242j does it and it ok.
    like they said keep your face from over the battery in case it goes wrong
     
  10. GregD1

    GregD1 Well-Known Member

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    Using a welder to jump start is about the worst piece of advice tht can be given. Do not do it !!! It is NOT worth it. I can`t remember how many controllers I have seen burnt up. I rewired a 1200 Hitachi excavator because of it. Cost the customer $11,000 by the time it was up and running again. Worst part is they knew the batteries were bad, the super on the job told their mechanic to do it, and they fired the mechanic for it.
    With everything being computerized these days, the welder battery charger is not a good idea. My $.02.
     
  11. Ronsii

    Ronsii Senior Member

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    If you have two different trucks/cars there you can put a pair on each one though... make sure none of the trucks or equipment is touching bumpers ;)
     
  12. still learn'n

    still learn'n Senior Member

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    I have jumped off of my miller trailblazer 302 how many times I put it in wire feed mode and set it on the right volts and then I get my mm out most of the time and check it and make sure it is the right volts and it always checks out to what the display says! I also haul equip and it happens that I get somewhere to pickup a piece of equip and it is dead I just pull my truck up there shut it off unhook 2 batt and make them 24 volt and jump it I have even pulled the batt out of semi and hauled them over by machine and did it worked great! I have never had very good luck with trying to jump a 24 volt system with a 12 volt like the other people were talkn bout but I believe if I waited long enuf it might work! My 2 bits Jerry
     
  13. d9gdon

    d9gdon Senior Member

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    I've never had any luck using 12V to jump a 24V system, probably from lack of patience.

    I started hauling around a small El Cheapo battery from Wally World and a battery cable that's about 2' long with terminals on it. I can set it on the grill guard of my pickup and slap the cable on from the positive of the mounted battery to the negative of my mobile battery. Then I can use jumper cables to go from the negative of the mounted battery and the positive from the mobile battery to get 24V. My pickup uses the side mounted posts for its system so the top mounted posts are free to use.

    Even if I'm not in my pickup, I can rig up this system faster with two sets of jumper cables and a swiped/borrowed battery quicker than I can jump it going the 12V way.
     
  14. ValleyFirewood

    ValleyFirewood Senior Member

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    That would work... after you disconnect the terminals from your truck.

     
  15. d9gdon

    d9gdon Senior Member

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    I guess you're gonna have to tell me why I'd need to disconnect my terminals. I must have gotten lucky several dozen times.
     
  16. ValleyFirewood

    ValleyFirewood Senior Member

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    Maybe I'm not thinking it out right?

    It would be feeding 24v into your truck is what I was thinking.
     
  17. GregD1

    GregD1 Well-Known Member

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    Let me rephrase the worst idea comment. If it works for you, great. If you look at the post count from a lot of the guys asking for help and it`s obvios their level of experience, I think it`s a bad idea to set them up to fail and potential damage to their machine. We have all done things that shouldn`t be done and got away with it. The next guy might not be so lucky.
     
  18. d9gdon

    d9gdon Senior Member

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    I see what you were thinking, but no it's the same as hooking up a 12V jump. Even though one's a negative post and one's a positive post on their respective batteries, both of the terminals become 12V positive in a 24V system. In the 24V series systems on equipment that I'm used to, you have one ground terminal, two 12V positive terminals, and one 24V terminal which goes to the starter.

    There's no comparison in jumping it 24V versus 12V, saves a lot of cussing for me not to mention that low voltage will fry a starter over time. I have it on my to do list to mount another battery under my hood that is already hooked up instead of hauling it around.
     
    Last edited: Dec 25, 2013
  19. Nelsonequip

    Nelsonequip Well-Known Member

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    If I don't have 24volt source I always hook up to pick up or whatever, as long as you hook up to 1 battery like you would another 12 volt system it's 12 volts I've done many time's but your best to do this to charge batteries one at a time and then try to start machine. That's what I always tell people when charging batteries with a welder disconnect welder before starting, and if your dealing with newer machine with a Ecm doesn't hurt to take battery cables off while charging :IMO
     
  20. Nelsonequip

    Nelsonequip Well-Known Member

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    Works fine if you know what your doing, your dead cell comment...to add to that also do not charge a cold battery with welder it will explode. And not good idea to leave welder connected while trying to start machine.