Hot Rods Welding Cable versus Battery Cable

I think this has been discussed before , but concerning connecting terminals to welding cable , here’s how I do it. I trim the insulation back as far as the terminal socket. I get the right size terminal for the wire. I use my cable crimping tool to crimp the terminal. I then put the terminal in my vise as short as possible, with the cable sticking straight up. I then take my butane torch and heat the terminal and let the solder flow into terminal until it’s full. I then cover all this with two layers of heat shrink! Never had any connection fail with this method in forty years of doing it. Just my way!




Bones

 

The current capacity of one particular gauge of wire is the same whether it is a solid wire or very fine strands.
From wikipedia:
"The AWG gauge of a stranded wire represents the sum of the cross-sectional areas of the individual strands; the gaps between strands are not counted. When made with circular strands, these gaps occupy about 25% of the wire area, thus requiring the overall bundle diameter to be about 13% larger than a solid wire of equal gauge."
As I understand it, the difference between the same gauge welding cable and automotive cable is the insulation and the "flexibility", not the current carrying capacity.

Also, the "skin effect" is really only at play in AC systems. DC systems typically have electrons flowing throughout the cross section of the wire.

 

50' of 1/0 weld cable supports 350 amps. Amp load is expoential because 100' requires 2/0 for the same load, but we can't assume 700 amps for 25' of the same cable. Still, the average use is probably under or a max of 20' and that would translate to likely 450 amps. Maybe. Maybe more, couldn't find a per foot rating, perhaps someone can add that. But this just in from the FWIW dept, my old 14:1 compression BBC used a stock starter and, you guessed it, welding cable. I did burn up a solenoid after 2 seasons but no other issues. I'd bet a gallon of gas that was more load than most everyone here is dealing with. I said most everyone @squirrel ...

 

That's not entirely true. It's really a voltage-based phenomena but DC systems very rarely reach the voltages where this becomes a major factor. There was some experimentation a number of years ago where the voltage was boosted into the million-volt range then somehow converted into DC then reconverted back at the other end that supposedly reduced line loss but still didn't eliminate it.

At 12 volts it's a non-factor....

 

heh....4 AWG battery cables from walmart on my blown 427. But what do I know.

 

I remember reading about this in HotDod years ago and if I remember correctly and I’m not saying I am the fine wire in welding cables offered less voltage drop per foot than battery cable. Quality Jumper cables are finer than battery cable.

 

When I first set up the old 14:1 427 in my 406 car around '77, my buddy who ran the warehouse for an electrical store/ contractor drug me down and we raided the scrap bin. Came out with a long scrap of 4/0 aluminum cable. Grabbed their big hydraulic crimper and ran the 4/0 from the trunk to a solenoid on the firewall below where the heater fan motor had been, right by the starter, and then a short piece of the 4/0 straight from the battery to the frame under the trunk for the ground. Used a short piece of welding cable from the solenoid to the starter, and another from the engine to the frame. Took a 302 smallblock starter, switched the nose to the 3-bolt version for the 427, and that setup is still on the car, spins the 427s hot or cold just fine. Total cost, a little sweat and lunch for my buddy

 

I use welding cable for the traditional reason.....it pisses people off.

 

So I will try to break it down a bit.

Welding wire is more fine strands inside the same dia wire gauge. So imagine the strands inside a wire being little current highways that flow electrons, the larger the strands there is more surface area but current doesn't care about that, current and high current that is, likes many small strands to get that flow all going smooth... There may be the same diameter in the wire, and as that is true, the finer the strands the more current it will flow without traffic jams.

Length of wire also plays a part for sure also. So where a 3' 8 gauge will be sufficient for an alternator to a starter. It would be way too much opposition to force at a 15' run and would heat up and probably fail. The longer the wire the more opposition to force there is.

Fine stranded wire is where its at in the automotive world, hence why you don't see the guys with the booming stereos running romex.

Solid core in the housing world is there for price, along with the wires dont have to move or give any, they are fixed installation. If you look at the feed to a house, its stranded wire. Also voltage pushing the current through the wire is drastically increased in the housing world vs the automotive. So the more voltage the more force the current has to drive it, the current is a measurement of the flow of electrons. So when voltage increases the current decreases. Hence why you can do a 12 v conversion and leave the wire gauges that are there cause they are over sized at that point but will not cause any issues at all.

Welding wire is above and beyond for our applications, but I like the added insurance of it for sure myself. And its cheaper normally than buying the high end stereo stuff also.

 

Right. I was going include "in automotive systems it's a non issue". I brought it up because there were a few comments stating that the welding cable would have better current flow because of the skin effect.

 

You have to be very careful when comparing 'ratings' from different sources. Most welding cable charts showing current capabilities assume that you're welding. Most welders operate in the 70 to 90 volt range, not the 12 volts we use. So a 25' length of 1/0 at 350 amps will have a 8% voltage drop at 12V. At 80 volts, it's only 1.3%. Bump the current up to 450 and now it's 10.5% @ 12V, but still a low 1.7% @ 80V.

Voltage drop is the ultimate enemy in our 12V systems. That drop doesn't just disappear, it's converted into heat. A 10.5% drop represents a 600 watt loss, or about 50 amps that's heating the wire. As the wire heats up, it's resistance increases, so the loss goes up too. That's why in a hard-starting scenario the longer you try, the slower the motor turns. Most cars require at least 10.5 volts to power both the starter and ignition system during starting and the 'typical' starting current is about 250 amps. Bigger and/or high-compression ones will need more, smaller motors will need less, but few cars or trucks will be less than 200 amps in any case. One of my motorcycles (1100 CC inline 4) draws about 90 amps. So assuming a 2V loss at 250 amps, that's roughly 40 amps that are being lost in the wire size.

You can apply any current you want to any wire, but at some point it will burst into flame and eventually melt. Keeping voltage drop down will make your system much more efficient.

I'll also note that modern permanent-magnet starters will reduce starting current (all else being equal) because no battery current is needed to generate the field windings.

 

25' is a really long run, half that would be typical. Unless you also have a really long ground wire, too. In that case, 25' is spot on.

 

Several opinions here about whether battery cable or welding cable has better current handling capacity, or that it makes no difference. I would say that probably for this application there is no measurable difference. But under extreme conditions there may be. I would also say that there is no definitive answer at this time as to how wires actually carry electrical energy, though there are a lot of theories about it, but they remain theories only. We can generate electricity, and we can control it and use it; and we know about and have even photographed actual electrons, but exactly what constitutes electrical energy remains somewhat of a mystery.

I've been following a bunch of youtube videos recently on this subject, the discussion was kicked off by a video made by a guy that does a lot of science and engneering videos, Veritasium, and his video on how electricity actually works was a bit controversial and caused quite a few other guys with video channels to make their own video challenging Veritasium's theories, and finally Veritasium's own response to all those challengers. I have to say that it's all beyond my understanding, but what this really shows is that nobody really knows for certain. Maybe people may think they do, and many people have their own understanding, but it remains one of those areas of science that really have never been fully understood.

If you're interested here's the video that kicked it all off:

From there you can follow links to the responses. Go ahead and offer your own explanation and theories if you want, but I'll include you in the same category as all the other experts; you don't really know, it's just your best understanding.

I would say that I think a cable made up of many smaller wires (i.e. welding cable) is better than one made up of a smaller number of larger wires (battery cable), but that's just my best guess based on my understanding. At least I'm honest enough to admit it's beyond my understanding. Anyone who claims to fully grasp it all, IMO, is only fooling themselves. If you think you've got it, go ahead and create your own video, let's see it.

 

Any electrical engineer worth his salt will tell you that there's aspects that aren't understood all that well. We have a pretty good practical knowledge, but still get caught out with occasional weird stuff. That's the main reason the NEC is revised every three years. I was in the trade long enough to see things be required, then became illegal, and in a few cases become required again. The proliferation of electronics (as different from just plain electrical) has driven most of the changes in the last 20 years.

We'll have to wait to see if the guy wins the Nobel prize or something.... LOL.

But with our simple 12V systems, nearly all of that stuff can be ignored.

 

I did almost the exact same thing on a big-inch FE cougar. In my case I used 2/0 copper (acquired for free), the biggest issue was forming it to fit the route I chose. Worked fine for as long as I owned the car.

The only issue I see with aluminum is it doesn't like vibration, it tends to break under that but properly supported should be fine.

 

My old Bronco broke down once and I stopped under a run of big tall electric towers. I dove under, bashed on the tank and got it running enough to drive the last mile + home. As I dragged my fat ass out from under it my bare arm touched the metal running board. I got shocked, not unlike when you were a kid and touched the back of the needle on your 45 record player (am I fuckin old or what?). So, what is this invisible energy that @Blues4U is speaking of? A cross between an elephant and a rhino.

 

No exaggeration here but I've dragged the same welding cable across dirt, gravel, asphalt, concrete and steel, rolled it up, gone on to the next job and done it again, over and over. I've done this in oil refineries, storage tanks, water towers, coal and oil fired boilers. Only time I've seen it go bad is if it hangs up on something and tears but if it is secured in a car, you're never going to have that happen. I too have used it for battery cable and never had a problem out of it. If you've got it, use it because it will probably outlast you.

 

Not really changing subjects Am I the only one here that has needed a few more feet of welding cable and used his jumper cables. but I have used welding cable for battery cable off the same roll for over 35 years. next car I wire with the battery in the back I will use some more of it

 

Yeah, same here. I think I've put welding cable through far worse exposure to oil and dirt and gravel, being stepped on and drug around using it on the jobsite than it is ever going to see being used as a battery cable in a car.

 

Agreed. That's why I said "probably for this application there is no measurable difference." If somebody thinks there is, I'd like to see it.

 

My welding cable to battery in trunk has been in for more than 40 years!

 

I have used welding cable in 4 cars now (with batteries in the trunk). Never a problem. I used welding cable at hydro electric dams for years . We didn't baby them. The insulation is supper tough / durable. I also read that the smaller strands of copper wire in them is better at current flow that the larger strands of battery cable. I remember it being very expensive but worth the difference IMHO.

 

Welding cable,,,,,soldered ends,,,,,,easy as it gets !
Welding cable will last longer than we will,,,,,in a car,,,,as a battery cable .
You are right,,,,,you need a couple of supports to route it and keep it in line on the frame .
My ground cable was a new battery cable,,,,,,I just ran it over to the frame ,,,,,shortened to the correct length,,,,,soldered a new end on it.
Easy as it gets !

Tommy

 

watched that video. all i can say if WOOF !!

 

After working as an electrician in power generation station for 45 years which included wiring new welding machines and using different AWG sizes . . . . I believe in my heart of hearts the wire doesn’t give a s**t whether it’s connected to a 295 AMP Lincoln 2/0 feed to the #4 AWG 15’ stinger, ground, or starting your car…..
All I know is all my race cars used extra flexible welding cable with heat shrink over the crimped part of the lugs no matter where the battery was located. I also use #8 extra flexible on our alternators.

 

On this last project, I was moving the battery into the truck bed (no room under the hood) and determined I needed 15' of battery cable.
Choices there days around here are pretty limited. Places you used to be able to buy bulk lengths of wire no longer have such things.
The last best option was the local farm store. The longest and heaviest battery cable there was #4 @ 10' long, and they were pretty proud of that one (and they only had one of those).
The next option was 1/0 welding cable, 25' length, cheaper then the 10' battery cable, but not cheap by any means, and I wanted two lengths, one red, one black. While pondering what to do, I noticed their store brand "best" 20' long #4 jumper cables were on sale for less then one 25' length of the welding cable and less then the one 10' battery cable. I bought the jumper cables. I ended up with the cable length of 12' each. This is not a high load motor, I think I'm going to be fine.

 

I can always buy used welding cable cheap at farm auctions or garage sales. I think it works great but then I'm the kind of guy that flattens copper tubing to make the ends.

 

One thing I would never do is install a trunk battery mount cable underneath the car. Only possible way I would do that is if were inside the frame rail and most of time that is not doable with sections of the frame enclosed. Too many possible incursions of junk flying up damaging the rubber protective cover.

 

Hell, the longest battery cable at the parts house is about 4 feet!

 

I search out 2/0 & 4/0 for battery cables, & grounds. Crimped w/a cable crimper, but I now prefer my hyd a/c-type crimper. Haven't found any welding cables in red, so's I just use 6-8" of red glue-shrink tubing on post terminals. I also dbl shrink tube the terminal ends for vibration help, after soldering, if I can. Only issues are: finding & funding the cables, & maybe the bend radius when things are really tight - & then it's pre-bent before shrink tubing gets done.

Squirrel, somehow I'm not surprised you run thin cables on the chev, w/o issue(s), for lighter weight/etc. . But I hear tell you use Electrickery in your cars... .
Marcus...