Up in smoke....

Discussion in 'Mistakes, Blunders and Boo Boos' started by Scrat, Oct 22, 2018.

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  1. Oct 22, 2018 #1

    Scrat

    Scrat

    Scrat

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    Building a 5" gauge battery-electric loco.
    Six huge axle-hung motors.
    Yesterday I wired the controller, checked if both bogies went the same way and had her roll a few cms up and down the bench.
    As the car batteries are quite heacy and had to go in and out several times during the process I used small 7 Ah lead-acid batteries.
    The car battery clamps would not fit these so I used alligator clips to connect them.
    Running to and fro without load was no problem but then I had the bright idea of checking how much power the loco had.
    I leaned against the buffer beam and let her go forward.

    *Flash of light*
    *lots of smoke*
    *electric smell*

    The stall current of each motor is higher than 50 Amps.
    Six motors vs flimsy alligator clips.
    A few patches of melted insulation inside the loco, nothing left of the wires.
    Clips were still in place.
    Will test with proper batteries this week.
     
  2. Oct 22, 2018 #2

    TonyM

    TonyM

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    Sounds like you didn't have fuses in the circuit and the wires acted as a fuse. Batteries can deliver many times more amps than their AH rating.
     
  3. Oct 22, 2018 #3

    Scrat

    Scrat

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    Hi Tony,

    I have fuses but those are rated at several amps to suit controller and motors. A simple alligator clip will glow at about 1.5 Amps.
    This was just a test setup.
     

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