eletric outboard overheating?

Discussion in 'Outboards' started by philipa9, Jan 11, 2014.

  1. philipa9
    Joined: Jan 2014
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    Location: nottinghamshire

    philipa9 Junior Member

    I recently purchased a second hand electric outboard and when I connect it to a battery the wires get really hot. what can I do to stop this??? does the battery bneed a lower amppage
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Do they get too hot to touch? Can you post the make and model?
     
  3. alan white
    Joined: Mar 2007
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    alan white Senior Member

    Sounds like a short in the motor. Does it run? Amperage is controlled by the motor. The battery's capacity shouldn't effect anything.
    Also, if you're testing with too small a wire, it will get hot.
     
  4. Stumble
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    Stumble Senior Member

    What size wires?
     
  5. PAR
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    PAR Yacht Designer/Builder

    Ditto the wire sizes questions and the battery size?
     
  6. philipa9
    Joined: Jan 2014
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    philipa9 Junior Member

    it is a minn kota 55ex its a 55lb thrust motor and the wires are aprox 4 mm wide including insulation
     
  7. Stumble
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    Stumble Senior Member

    No idea then what gague your wire really is. 4mm diameter could mean anything in terms of what the conductor size is. But let's assume the conductor is 2mm... So you have 3.14mm^2 conductor area which comes out to 8 gague wire. For a 50amp max draw (which Minn Kota says this motor draws), that would give you a max allowable run distance (battery-motor-back to battery) of 12 foot, and even that's pushing it.

    Measure the distance from the battery all the way to the motor, then back and take a look at http://www.westmarine.com/webapp/wc...w?storeId=11151&page=Marine-Wire#.UtH30H-9KSM 3% loss chart to determine what size wire you need to be using.

    Additionally is this stranded tinned copper wire, or something else?
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The MinnKota 55ex should draw about 50 amps, which suggests you'll want a minimum of 8 gauge (AWG) on anything other then a very short distance. You just need to do some simple math, to cover voltage drop, which should be less then an amp. How far away is the battery? Are both wires the same gauge? Anything else in the circuit, such as foot switches, etc.? All these thing will affect the wire size and the amount of resistance it experiences (which makes heat).

    You need 8 gauge for 10' or less, 6 for 15', 4 for 25', 2 for 40'
     
  9. philipa9
    Joined: Jan 2014
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    philipa9 Junior Member

    the motor is 3 to 4 foot from the battery and whats that un English
     

  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    8 gauge (AWG) should be fine. If it still gets hot, you have another issue.
     
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