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switch harness and wire length

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Old 05-09-2014, 06:32 PM
  #1
roydefiant
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Default switch harness and wire length

In order to balance a new jet the A123 batteries must be in fuse but heavy duty switch harnesses (18 gauge wire) are 4 feet away in nose hatch. I will be running 16 gauge wire from batteries 4 feet up to switch and then 4 feet back to power expander/receiver in fuse. The same will be true for lipo battery for turbine ECU. My nephew who is an electrical engineer tells me there should not be a problem with any significant voltage drop as long as everything is heavy gauge wire. Anyone with experience with this type of setup?
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Old 05-10-2014, 04:33 AM
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dirtybird
 
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I dont fly jets but I I have a toaster that runs off 40 ft of #16 wire. It pulls about 10 amps.
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Old 05-10-2014, 05:42 AM
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Quote:
Originally Posted by dirtybird View Post
I dont fly jets but I I have a toaster that runs off 40 ft of #16 wire. It pulls about 10 amps.
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I would move the switch if possible.
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Old 05-10-2014, 09:15 AM
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long wires on the power input to an ECU can lead to excessive ripple voltage at the input, damage to the input caps. Too much inductance, the pulsed current driving the motor leads to the ripple. You'd be better off extending the wires from the motor to the ECU and moving the ECU closer to the battery. Either that, or add extra capacitance to the input of the speed control. Dig around in the high performance electric plane forum for more info.
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Old 05-10-2014, 10:10 AM
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Quote:
Originally Posted by fizzwater2 View Post
long wires on the power input to an ECU can lead to excessive ripple voltage at the input, damage to the input caps. Too much inductance, the pulsed current driving the motor leads to the ripple. You'd be better off extending the wires from the motor to the ECU and moving the ECU closer to the battery. Either that, or add extra capacitance to the input of the speed control. Dig around in the high performance electric plane forum for more info.
He said a jet. I dont think it uses an ESC

Ata current of 5A the voltage loss of 8ft will be 0.8v
The free air max current is 22 amps but in a bundle its 3.7A
Dont put it in a tube

Last edited by dirtybird; 05-10-2014 at 10:56 AM.
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Old 05-10-2014, 10:55 AM
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Right you are.. my fault. Thanks for the heads up!
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