Negative Battery cable gets hot,no start

Discussion in 'Electrical Systems' started by AMP, Aug 28, 2011.

  1. AMP

    AMP Veteran Member

    Hi,my 79 has an issue with batteries!There must be some kind of draw because the battery will go dead overnight if cables are left on it,only symptom ive noticed is a hot negative battery cable when i crank the engine.any thoughts?
     
  2. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

    25,228
    269
    Feb 26, 2004
    Bloomington, MN
    Resistance = heat

    You may have a poor ground connection.
    It sounds like you have a drain somewhere else too.

    Disconnect the positive cable from the battery terminal and use a test light to bridge the circuit.
    Then... unplug the alternator and see if it goes out.

    If it doesn't, pull fuses until you find the one using power. (Test light goes out.)
    The clock only uses power in little spurts, you don't need to disconnect it to find your short.
     
  3. grzewnicki

    grzewnicki Veteran Member Lifetime Gold Member

    Usually high resistance (poor connection) will cause wires to get hot. Check both ends for being tight and corrosion.
     
  4. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    yup, higher current and voltage drop...
     
  5. 71flh

    71flh Veteran Member

    910
    10
    Jun 1, 2010
    DFW
    Nope. A resistance (in series here) where it doesn't belong reduces current.
     
  6. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    which means it draws more current to do the job... which is what causes the heat.

    26 yr electrical engineer.. but not worth argueing over..:screwup:
     
  7. 71flh

    71flh Veteran Member

    910
    10
    Jun 1, 2010
    DFW
    Time to go back to Ohm's Law and read what happens when resistance increases in a series circuit.
    I=E/R
     
  8. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    whatever:screwup:

    power = current squared x resistance
     
  9. 71flh

    71flh Veteran Member

    910
    10
    Jun 1, 2010
    DFW
    I just have a problem with nonsense presented as truth. Sorry.
     
  10. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    seems to me that you are considering a regulated power supply.. a battery ain't a regulated supply..


    so let's just agree to disagree and move on.

    clean all connections and then check the resistance of the cables with a VOM (possibly corrosion inside the connector itself)... that should steer the OP in the correct direction.
     

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