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Thread: 12 Volt power loss

              
   
   
  1. #1
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    12 Volt power loss

    I got my rig all set up (72V KZ440 with a ME1003)when I noticed a problem... It won't run.
    My contractor won't move when I turn the key.
    I hooked up the volt meter to the fuse box and see my problem.
    After a quick diagnostic I see I lose almost all my voltage (12V) when I turn the key. Does this mean I have one of my positives from my ignition hooked up to a ground somewhere?

  2. #2
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    Post a schematic please. What controller are you using? Sounds like something is shorting out your 12V or drawing more than you can supply...DC-DC or battery for the 12V source?

    I am also building a 72V KZ440 with an ME1003, what year and what is your pack like?

    Steve

  3. #3
    Senior Member billmi's Avatar
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    If you do have a positive hooked to ground, that would do it, but it should also blow one of your 12v fuses in the process.
    What is providing your 12v supply and what is its capacity?
    What do you have drawing 12v (contactor, headlight, etc.)?
    Sensei - Electric Ninja 250

  4. #4
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    I have the 1980/81 KZ440 LTD
    I will get my schematic up asap. I am using the
    AXE7245,
    SW200 72 volt Solenoid,
    but I have a cheap DC2DC. Green Galaxy 10amp (http://www.thunderstruck-ev.com/gree...xy-36-72v.html).

    Drawing off the DC converter... Headlight, warning light (3.2w), contactor, horn, controller.

    I think I will try to hook up a 12 car battery to the output of my DC2DC instead of the converter and see if it is just underpowered.

    Thanks for all the help so far, you guys are awesome!

  5. #5
    Ghost Rider Allen_okc's Avatar
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    can you just use a 72 volt contactor???

    run a DCtoDC converter from the 72 volts to power the 12 volt...
    The Greatest thing about a EV, is the Song of the Terrain...

  6. #6
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    I do, the SW200 is a 72V contactor http://www.evdrives.com/contactors_SW200.html

  7. #7
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    I don't think this is part of my power loss problem, but I do need help wiring my contactor. I have the sw200, http://www.evdrives.com/contactors_SW200.html
    What wires should I connect where? four contacts, four wires (12V +,- and Coil #2 anode, #1cathode)IMG_20120412_112628.jpg

  8. #8
    Empulse R #24 frodus's Avatar
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    You said it's a 72v contactor. That normally means the coil is 72v. Why are you using 12v?
    Travis

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  10. #9
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    I think we are getting somewhere. I need to activate the contactor with 72V? How do I do that? I am getting a diagram up now.

  11. #10
    Empulse R #24 frodus's Avatar
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    That's why we usually use 12v coils. You have to run pack voltage through the key switch to the contactor coil.

    Read the manual for the axe7245. It shows how to wire it.
    Travis

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