Technical Battery Cable Gauge Opinions Needed

It does sound fascinating...but also, probably not so good an idea. Something about the limited fatigue life, and that pesky oxidation thing...

 

Aluminum wire is just as good as copper, as long as you terminate it right, don't let it move around, and keep it from corroding. All things that can be done with the right products and installation.... but I wouldn't recommend it to the average guy.

 

My goodness, I missed a lot in a couple days....I'm surprised this took off the way it did, but that's how I learn stuff.
Its always interesting to hear other points of view, and why people do things the way they do. I saw what Squirrel said about putting the battery close to the motor and using as short and as small of a cable as he could. Makes perfect sense in his world, he's got enough power and traction that he's trying to keep the nose down anyway, and overall lightness is important. Cheap is just a bonus.
Imagine a different world...enduro racing on a dirt track. They dont throw the caution unless somebody gets upside down.So you get turned sideways, at the end of the straightaway, drivers door facing the traffic. Now is when you are glad that you have two 1000 CCA batteries in the trunk, ( for some extra rear percentage), 1/0 welding cable for battery cables, and a special built starter, because when you reach up there to hit that starter button, you want to make GODDAMN sure that the bastard will spin over. If it dont start and run, you can put it in gear and limp off the track so you dont get run over. Granted, 80 mph is not that fast, but if you're sitting still and get hit in the drivers door, you spend that extra money to try to not let it happen again.
As for the special starter...the guy who built it for me had a Ford armature pressed onto a Chevrolet shaft and he put Diesel brushes in it , to give it more torque. I'm sure somebody will tell me this is BS, and it may be, but that's what the guy told me and I was young and believed it. I do know it was better that a normal starter and we couldnt use the gear reduction starters back then because they werent "stock".

 

Exactly....the very first thing you have to do on any engineering project, is define the requirements. (you probably didn't even know that this is an engineering project!)

For a street driven hot rod, not being raced, the requirements are probably:
1. Reliability
2. Appearance
3. Cost

but the order will be different for each person, depending on tastes and circumstances.

The appearance thing might mean the battery should be hidden away. That will kind of require long wire(s), which will cost more, and probably affect reliability (since maintenance is more difficult and less likely to be performed if you can't see or reach the parts).

The cost of the battery can also affect the reliability and the appearance. If you spend big bucks for a battery, it might make it more ugly, or more pretty, depending on your tastes. It might be a more reliable battery, with extra CCA and reserve, which will help reliability. Or it might be a repop resto type battery that costs a fortune and doesn't last long.

All kinds of fun things to consider...

 

Just a few comments and questions...whether your wiring a house or a car, when you read books on the subject, for obvious reason they almost always caution against using a wire that is too small, but almost never even discuss a wire that is too big. My limited knowledge of wiring would suggest using wires that are bigger than required are not a safety issue, but I'll ask...is that assumption correct, and are there issues that could arise from using wires too big?
my second question...years ago when rewiring my house, I read several books that all cautioned about not scratching the striped wire as you're attaching to terminals or twisting together for wirenuts. Only one book I ever read actually went on to give the reason for this, and frankly it was an eye opener for me.....they explained electricity does not travel through wires, it travels on wires. (heat buildup from the electricity jumping the gap caused by the scratch)
So if that is correct, wouldn't aluminum wires oxidizing be an eventual problem?..... Also, I believe a cable with finer strands carries more current because if electricity travels on wires as stated, there is much more surface area in a cable with more strands per a given size.
That leads to my last question...is a multi stranded wires' gage size determined by the surface area of the strands or the volume of the strands?

 

Skin effect is something that happens with alternating current (AC), not with direct current (DC). That makes it important for power transmission, but not for cars. And not for house wiring, because the skin effect at 60 hz is not very big, so the wire will not be affected much by it (because the wires are much smaller diameter, than the depth of the skin effect).

 

to answer your other questions...using wire that is larger than necessary costs a lot. And it's heavy. If that's not a concern, then don't worry about it.

And nicking wires is a bad idea, because it might cause the wire to break, right? The story that you stated sounds like a load of baloney.

 

In order.....

Electrically, there's no downside to larger wire. Larger wire reduces voltage drop which reduces heat and additional load in the system, which makes the system more efficient. Installing extra-large wire can be a problem though; once you get above #10 wire, finding terminals for many automotive devices becomes impossible. In terms of plug-in connections, you're limited to #10 wire because there aren't any terminations made for larger wire except for some special proprietary ones used by some manufacturers which will be neither cheap nor easy to get. Any connection above 24 continuous amps should be bolted, not plug-in. And once you go above #10 wire, you'll need special dedicated crimpers; the one-hand units won't do it. This was a major problem in the past due to crimper costs, but with inexpensive imported hydraulic crimpers now available for well under $100, much less of an issue these days.

'Nicking' or scratching the wire. This is a real thing. But it's a serious issue only on aluminum wire; copper will rarely have an issue unless conductor movement is involved or if it's badly gouged. It has more to do with the fact that aluminum wire will break very easily if a nick or scratch is present, as well as develop 'hot spots' at the nick. I have seen aluminum wire burned in two when the original installer nicked the wire. Properly-done terminations are critical with aluminum conductors...

'Skin Effect'. As Jim said, this is primarily an AC phenomena. It is present in DC circuits, but only during 'current inrush'; once inrush is done, it disappears. The amount of current in the conductor also affects this (which is one reason why any wire larger than #6 is required to be stranded; more conductor surface area) but unless you're a power utility needing every last bit of efficiency, it can be ignored for circuit calculations. And even at 60 Hz, at power generation plants and while transmitting power it's very much taken into consideration. It's funny, this term came into 'popular' usage with the advent of big $$ 'high performance' home audio speaker cables with all sorts of outlandish techno-gabble claims being made about how much better these were compared to the usual inexpensive lamp cord generally used for speaker connections (Skin Effect! Gold Plated Connectors! Oxygen-free Copper!). A highly-respected audio reviewer at the old 'Stereo Review' by the name of Julian Hirsch put up a $10,000 bond that would be paid to any cable manufacturer who could prove in a double-blind listening test that their cable was sonically better than lamp cord. He never paid off.... although many tried.

Lastly, wire gauge size is determined by the total cross-sectional area of the conductor or conductors in a cable as measured in circular mils, with each AWG (American Wire Gauge) size having a given cross-section area. Above 4/0 sizes, wire size is given directly in circular mils abbreviated by thousands. So a 250 MCM or Kcmil is 250,000 CM, 350 MCM is 350,000 CM, etc. When you get into the larger sizes (1/0 and larger), you can run into 'compact' sizes where the individual conductors aren't round but shaped so they 'nest' with each other, reducing space in between them to the minimum.

 

Thanks Sqirrell and Steve for the explanation.

 

Just to clarify, electricity is conducted through the entire mass of a conductor, not only along the surface. There may be something known as "skin effect" the guys above mentioned, but that should not be taken to mean that the core of a wire does not conduct electricity, that is just wrong. Even in AC audio circuits, the frequencies affected by skin effect are beyond the audible range. The high end audio world is full of hucksters and shills, don't be a sucker.

Steve, as I recall, one high end audio magazine did a test between different speaker wires, and also included straightened coat hangers in the test, and nobody in a blind test could identify which was which. I've had plenty of online "discussions" with other guitar amp techs and this whole area is very controversial. But high end audio takes it to a whole different level.

 

Actually that info I read on electricity traveling ON wire was in a do-it-yourself home wiring book...either Sunset or Black and Decker.....so no high end audio salesmen involved....Now I've rewired both my home 6 years ago and my car last year...no flames yet, lol.
BTW, somebody earlier commented on the Ron Francis suggestion of wiring a car as if it were a fiberglass car. I took that suggestion and glad I did. My car's chassis system and efi engine harness are all Ron Francis. I did not buy their grounding kit...just used aftermarket terminals and power distribution boxes for the grounding back to the battery. This was my first attempt at wiring, and the only issues I've had electrically were both on non Ron Francis hd trailer-type connectors I used on the tailights. No grounding issues whatsoever, and nothing on my car is grounded to the body or frame, other than I did run the HD straps between engine/frame/body near the starter. I personally think it's a great reliable way to go. If I do have issues down the road, I know exactly where to check the grounding connections. Just my 2cents.
Yes, I am aware that when you use wires for the grounding instead of the body, that extra length/run has to be taken into consideration determining wire gage.

 

Hmmm..... LOT'S of good info here. Possibly the best "battery wire" thread to date. Yea, I'm printing all this out.

 

huh....I was just havin' fun....

 

Has anyone used the compression screw on type battery connectors? What do you think of them instead of soldering?

Taylor Battery Cable Terminal Kits 21412

BATTERY CABLE TERMINAL KITS

• Battery Cable Terminal Kits
  
• These Tin plated copper compression battery cable terminals are designed for a fast and easy install
• Simply strip your battery cable and apply fitting to cable and screw into battery terminal
• Tin plated copper terminals and compression fittings are cadium-plated for corrosion resistance

PRODUCT PART #
2 ga. Battery terminal 2/pkg 21405
2 ga. Battery terminal 1/pkg 21406
2 ga. Battery eyelet terminal 2/pkg 21409
2 ga. Battery eyelet terminal 1/pkg 21410
1-1/0-ga. Battery terminal 1/pkg 21412
1-1/0-ga. Battery eyelet terminal 1/pkg 21414
*To buy a specific product, simply click on the part number listed above.

 

these are NICE --->

 

i have those and a disconnect

 

Yes, similar to those. These were the compression fittings that I was looking at. Something like these.....Pretty much the same thing as yours. I like your's a lot more.
1-1/0-ga. Battery terminal 1/pkg 21412

 

and those WORK too

 

That disconnect is just flat dangerous.... right below it on the battery cap it says...'Danger! Explosive gases! NO sparks!'... If you must have a battery disconnect, mount it a reasonable distance away from the battery.

As to those compression terminals, I'd stay away from those. A properly crimped termination is always better than a threaded/bolted connection. And given their cost, why use them? At $25 a pair, you'll have $50 into just your cable ends. Considering that you can buy four crimp ends for about the same as one of those AND buy a imported hydraulic crimper for the difference (and have the tool for future use), which would you choose?

https://jet.com/product/detail/044d...15&gclid=COnFucyf1s8CFYbgfgodoKoEbg&gclsrc=ds

 

CS is correct...
its just one of 10,000 options, i actually do not have those EXACT ones
my disconnects are of the type used on / in RACE cars

 

Just for shits and giggles, I thought I would try to put some real numbers up for reference. I meant to do it before, but I had to wait until my grand daughter could come over to help me. I had a Fluke clamp on ammeter that I borrowed, and I didnt attempt to measure the inrush current, but I could see it was a bit higher on all of them. What I did was just have her spin it over for several seconds, until it was more or less constant and then write the number down that was showing on the meter.
The first one was kind of comical, she just kept winding the starter, even though it was running. I took the coil wire off for the rest.
1- 1955 Chevy 235 6cyl- 12V- 160 Amps
2-Stock Model A 4cyl- 6V- 160 Amps
3- Stock 390 Ford FE-12V- 155 Amps
4- Stock SBC 350 -12V- 205 Amps
5- Stock Model A - 12V- 200 Amps
The last one was a little puzzling, I had expected it to be lower than the 6V one. What might have skewed the data was that the battery in the car was dead, and I just jumped it off with another vehicle.
I didnt make any attempt to lower any of the values by cleaning the posts, cables, ground connections, etc. Just cranked it like it was sitting there in the yard. I wished I had been able to have a high compression SBC both with a mini-starter and a stock one to compare, but I dont have one to check without some work right now and this was just a quick and dirty test.
I hope maybe somebody can get some good use out of this. Good Luck

 

kind of what I would expect. Thanks!