Fine vs Course

i went to homedepot to get some 4 gauge wire for batttery relocation

and the guy said that this wire strands are course and cant handle low voltage. because there is more surface area on course wire (true) and power is transferd on the outside of the wire.

is this true

i thought 4awg copper wire is 4awg copper wire

 

Yes, that is true. Get automotive grade cable.

 

I get wire intended for making welding cables and it works great and is cheap.
I get mine from princess auto, about 1.50$ a foot i think

 

Since electrons actually travel across the surface of the strands, having more surface area is the solution. Since your intended purpose is to carry high amperage (current flow) with relatively low voltage (current pressure) you will need more surface area. Household wiring in the US is designed for standard usage at 110 volts with a lower amperage draw thus needing less surface area for the current flow. HTH

 

Another thing to point out is that finely-stranded automotive wire is MUCH more flexible than building wiring with more coarse strands. That stuff at the hardware store is insanely stiff to be routing through the tight confines of a car.

 

as a electrical engineer, I will tell you want fine versus coarse. There is never any need for thick cable. Automitive cable even at 22 gauge will handle 600V. The overall guage size is what Amperes the wire can handle over a certain distance. For battery relocation 4 guage is more than enough. In fact, when I reviewed the chart 10 gauge can handle 100A for 10 feet, or 6gauge for 15'. Hope this helps.

 

Notfastenough has it partially correct, but to explain it a bit more.

Alternating current travels on the center of the wire, direct current travels on the outer surface of the wire. Thats why amplifiers and automotive cables are made of fine strands, that way theres alot more surface area for electrons to travel on, versus the 1-6 or so strands that they use in housing electricals.

Also the fact that they flex alot more when theres more strands, makes it the right choice for auto use.

 

I wouldn't go any smaller than 2 ga. for battery relocation.

Reason is that I did it myself on my old Toyota Camry back in the day - Optima battery in trunk with 4-ga. wiring up to the original battery location, with a 100-amp fuse near the battery. After a few days the link inside the fuse started to deform and melt, and it would have been only a matter of time before it blew. I switched to 150-amp fuse and didn't have any problems, but that wasn't the best choice. I sold the car shortly after that so I just put a normal battery back in the normal location at that time.

 

No, I agree because you don't want the wire to be right at its limit. 4 gauge handles 150A at 15'. That should do, unless you may have accesories running off the battery, like an amp, then use 2 gauge.

And be aware that when you replace the fuse with a higher rating, you are effecting the ciruitry of what the fuse coonects. I have done in class and on my car as well. I thought I could replace the lower fuse with a higher fuse so I could run run my fogs off the running light circuit. I eventually blew my dimmer switch, witch apparently is in series with every thing else in that circuit. I had to buy a new dimmer and rewired the fogs to operate the relay off the main power but the swith is connected to key in ON position so the fogs switch off when the car is off.

 

at a certant temperture

with that said building wire is stiffer bcuz we pull it thru pipes vs welding cable

welding cable gives u a better contact/bond but coarse is alot stronger both at the same size will give u the same amperage

also alot of people are confused about voltage drop,there two ways this occurs to small a wire(in a non ventilated area or in a hot area) or a bad connect

wire generates heat and multiple wires in a bundle generates more heat(we call this bundling wires this can also decrease amperage or create voltage drop

0-1/0 is overkill unless u have a alternator/batteries that can suply that amount of current

 

I was not aware that A/C was in the center of the wire. Learn something every day ;-)

 

4ga welding cable FTW.
Run from batt. directly to starter motor, install ANL fuse as close to batt. as possible, run a jumper from starter motor to engine bay fuse box, do not install splitter/fuse blocks, they just add resistance, solder all ring terminals to cable, do not use a "cinch/set screw" type fuse holder, a simple post and nut type is much better. 94