I am in the process of making a pair of jump starter cables and I need 4 alligator type clamps.
I was searching for pure copper clamps but didn’t find any. All commercial clamps are actually made of steel and just plated with copper.
But I did find brass clamps. Is brass as good as copper for driving large amounts of current?
The conductivity of brass is about 28% of the conductitity of copper.
since current flows outside the conductor, copper plating steel does the trick.
Why do you need pure copper? What currents do you need to pass through them?
DC flows through the entire conductor. AC has skin effect.
Anyway, OP: I usually see steel or brass clamps with copper jaw inserts.
Around 400A, but only for short periods of time, basically for starting a car
damn, that is embracing, lol, thanks.
now that i think of it, i had a booster long time ago, it had plastic clamps, but the ends looked copper, they were more red than yellow, just like copper plumbing pipes\fittings. i might still have them, i’ll check when i get home
Nah, only at super high frequency. Goggle “skin effect”.
At DC, there’s uniform distribution through the entire conducting surface. Cu plating is only to make it look like Cu, and to keep it from rusting. So it’s largely only as conductive as solid steel.
Damnit… beat me to it. :laughing:
Why not help yourself modding a steel plated one simply by soldering bypass wires near the wire crimp spot to the clamps front?
Also high quality ones may have a really thick coating of quite a few mm² to get an overall decent resistance, just needs more time and copper while electroplating
Edit; nvmnd, clamps found below
here you go, 800A Heavy Duty Pure Copper Jumper Cables Boost Clamp Car Battery Charger Clamps
Heres another option. These are more like what lexel mentioned above. They kindof have a wire bypass built into them. I personaly use one for my mig welders grounding clamp.
https://www.ebay.com/i/352514687682?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=352514687682&targetid=883121439742&device=m&mktype=pla&googleloc=9031148&poi=&campaignid=9418895015&mkgroupid=95235844546&rlsatarget=aud-496202329659:pla-883121439742&abcId=1141016&merchantid=138166597&gclid=Cj0KCQiAwP3yBRCkARIsAABGiPrhM-iSGHhP3iR9ofdfG47-4fulvIWKwmkzxJvTZc4LYIhPrtv2OicaAnlkEALw_wcB
Copper can not be suitable everywhere. You need long flexible wires with low resistance, and they are usually copper.
If you have a short rigid clamp jaw, it can be made from other metals. It will still have reasonable resistance, but won’t be so soft and bent easily.
I have disassembled many high-current breakers - usually, there is no copper inside, mostly nickel-plated brass or steel.
P.S. For clamp jaws, clamping force and ability to “protrude” into battery terminal (through all dust and grease) matters much more than electrical resistance.
all depends on how thick the sheet of copper is.
a short story, many years ago, i was leaving my friends house and used their plastic shoe horn, it broke, so i got them a metal one, from relatively thin stainless steel, as i tried to use it, it bent.
so i said to myself, if i can’t find a shoehorn strong enough for me, i have to make one, i had a piece of copper 2,5 or 3 inch pipe, about 2 feet long, i cut it along the length in 3 pieces. used bench grinder to shape them into shoe horns, sanded and polished, i tried to bend one on purpose, while putting on my shoes, i destroyed a pair of shoes, but the shoehorn did not bent even a little,
2 others i gave away, 1 to a friend whose SH i broke, and other to another friend, unfortunately the other friend had his house burned down, and my shoe horn was the only thing that survived, he still has it.
later i made about half a dozen more, but from EMT pipe, one i made about 3 feet long, and shaped it as a japanese sword, with a nice handle, not only it is great as a shoehorn, but it can be used in self defence, as a heavy blunt object.
so my point is copper can be strong, if thickness it right, even if plumbing copper pipe isn’t pure copper, it still has very high conductivity index, whether it makes any sense is a different story, many battery terminals made out of lead, conductivity index of lead is 7 vs 100 for pure copper, when you clamp to such terminal, any benefit of copper jaws will be negated by lead terminal. steel has conductivity index 5-13 iirc depending on grade, brass 28.
For cables I will be using chinese 6 awg silicone cable 
They are a bit thinner then the ones used in commercial starter cables, but much heavier. I think its because the commercial cables have aluminium inside that is only plated with copper.
what is the melting point of silicone?
It’s written 200 C on them.
you are a brave man, kat, i wouldn’t even try to run 400A thru a 6awg wire, possible outcomes scare the crap out of me.