Up in smoke....

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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.
 

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.
 

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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