Howdy all! Okay I've got some electric basics, but I'd like some help to grasp a concept that eludes me somehow. The question is " why the super heavy cables on certain vehicle wiring circuits?" Like winch wiring or some sound systems. I've seen 440V AC motors running on cables of similar thickness, so where is all the amps in a 12V automotive circuit? I'm not looking at something from the proper perspective in regard to E=IR. Thanks!

 

well with the sound systems its a pretty simple calculation Wattage = Amps x Voltage, so if you have a 1500w amplifier running on the 12v circuit that amplifier is pulling 125 amps.

pulling more amps requires heavier gauge wire which reduces the resistance, this is important because the more resistance the more heat is created in the wire, this reduces the chance of melting the insulation and causing an electrical fire.

With a winch the current draw is based upon the load its pulling, a Warn XD9000 winch has a 4.6HP electric motor, rated to pull 9000lb, its maximum current draw is 460A, thats a maximum of 5520 Watts!

Now the current draw is all Dependant on the load on the motor, which on the winch is the weight of the object being pulled... the heavier the rig, or the more stuck it is, the more amps its going to draw, so thats where you need those big heavy cables and why most people run dual batteries and deep cycles.

im not going to go into the details of AC circuits... i still dont fully get how it works... DC is so much simpler. a load and a ground.

 

Well thanks for that! I should have known all that anyway, but I just couldn't get it. Somehow I think 12V = no power. Some sort of misconception