I use 1/0 welding cable from the tractor store from the trunk to the inside of the firewall under the dash where I mount the solenoid. Then a regular parts store battery cable that's oil resistant etc through the firewall to the starter. Cranks up small blocks in the dead of winter just fine.
Probably 00 actual Battery cable. I'm not a big fan of trunk/rear mounted batteries but sometimes that is where it has to be. I also like to run a smaller (like 1 or 2 ga) dedicated ground from where it grounds the frame at the rear to the starter. I know that is overkill most likely but I'd rather have more ground capacity than needed than less. A lot of wiring schemes do not think about the grounds. You need just as much grounding capacity as positive capacity.
I'd rather have a breaker/fuse pop than a wire short and start a fire, wouldn't you? Building cars for customers, you never know what they're going to do. I've seen some pretty dumb ****. That said, you have to ***ume for the worst and plan accordingly.
Bigger is better, personally I almost always use one size larger wire. Also the longer the run the more voltage drop you get, this is especially true at lower voltages.
A 2/0 cable is going to be an appropriate size for a 12V system from battery to starter. You don't need 4/0. Skin effect only applies to AC circuits. DC circuits will flow current through the entirety of the conductor's cross-section. Current carrying capacity is not related to strand count. An X gauge fine-stranded cable will have the same ampacity as a single-stranded one. Stranding only gets you flexibility in the DC realm.
Those charts are for standard house or commercial wiring, not for fine strand welding cable amperages. Fine strand is more than double what those charts show.
A solid diameter single conductor is the highest amperage rating anyone could find. It's what most high voltage main lines are made of. It's of course too ridged to use for almost any other application. Circular mils will increase the finer the strands are inside one sheath, so fine strand wire does indeed have higher current carrying ampacity because of the lack of gaps between strands. It's about as close as you can get to a solid single wire of equal diameter. But it's not quite the same as a single solid strand.
You do realize that with automotive electrical wire the smaller the number the larger the wire meaning that 2/0 is quite a bit larger than 4/0 Wire?. Just as it is accepted that a 6 volt system needs the larger cables and wires to have less resistance for the 6 volt battery to push th1e amps through a 12 volt battery does better pushing amps though a heavier 2/0 cable rather than a rather skinny 4/0 cable. New cars with every electrical component in the car get away fine with 4/0 cable simply because normally every connection is good and the is a minimum of resistance in the system. Older rigs like my 77 1 ton with a 454 (common hot rod engine) don't always have the best connections, components in the best condition or wiring in the best shape.
That seems to be the way Solar installation folks but I'll damned well guarantee If you load up and go to the parts house right now and look at the 4 gauge battery cable =12 volt and the 2 or 1 gauge cable the 2 or 1 is larger in diameter. I'm tired of fools who ******** go off the wrong information just hauls your *** down to the parts house and look for yourself.
Hold on fellas, were getting crossed up here; Wire numbering has a goofy split at 1 gauge. Starting at 1 gauge and shrinking in size, the bigger the number, the smaller the wire, and going the other way from 1 gauge, that is, 1/ought, 2/ought, etc., it gets fatter.
Oughts are a whole different thing. A 00 is smaller than a 0000. One should not ought to be too testy. I didn’t get testy above when I was schooled about current on the surface of AC vs DC. Hopefully folks who read a thread will read all the words.
Well stated Thank you I learned a few things one of which is welding wire does have a higher amp carrying ability vs standard wire for any given wire ga. due to more wire strands- make sense. Dan
And I’m tired of the fools who fail to admit they may be wrong…yes as the number gets smaller the wire gets bigger until you get to zero then you get into the oughts, which start going up. Obviously you missed that day at the spit and whittle club.
Not sure where you got that info, but it's not correct. 4/0 is much larger than 2/0 and carries far more amperage. What you say it true up to #1 size, but after that the more zeros after the number the larger and higher amperage it is. Check out this chart at Cerowire: https://www.cerrowire.com/wp-content/uploads/2021/04/Cerrowire_Ampacity_Chart_210405.pdf
Well I know that the bore of a 12 gauge is the size of a ball of lead that equals 12 to a pound... One tenth of a pound of lead in ball shape is the diameter of a 10 gauge.... and a 20gauge is the diameter of a ball of lead that's 20 to a lb. After that it all gets fuzzy. -rick
You do realize that #4 cable is NOT the same thing as 4/0 cable, which is a much larger diameter. #4 cable is what the factory likely used for the battery in your engine compartment. 4/0 cable is used when you want super overkill for a battery moved to the trunk.
Jesus man…you’re mistaken on this. 4 gauge wire is smaller than 2 gauge wire, 4 ought wire which is what you said, is bigger than 2 ought. You can spin it however you want but it doesn’t change that fact.
I may be getting 4 gauge and 4/0 mixed up as I was only thinking in automotive sizes, Still we have gotten way to hell and gone off base from the OP's original question about battery cables. And that goes back to the simple answer that the heavier cables required for 6 volt operation will work better for 12 volt operation than the quite 12 volt cables. If you go out and crank your big engine hot rod and then reach down and grab that "12 volt cable" and it is hot that cable is too small to carry the amp load that your starter is demanding from the battery. Then it all went down hill from there when someone dug up an industrial electric wiring chart that lists electric cable sizes all together different than automotive does. Probably the reason that when it comes to AC electrical for my house or garage I call one of my brothers who are both Journeymen electricians to do the work rather than dealing with it myself too. I've probably been wrong on the 1/0 and 4/0 or 00 wire sizes for the past 50 years ago as it was always my info that the higher the number the smaller the cable.
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