Is plumbing copper, refrigeration copper bad alloy for electric?

Is there usually aluminum or some other crap mixed in with plumbing or refrigeration copper ? I want to make my own battery lugs, to save money.

DocStein99:
Is there usually aluminum or some other crap mixed in with plumbing or refrigeration copper ? I want to make my own battery lugs, to save money.

Google is our friend. google : "refrigeration tube copper purity"

Plumbing solder has a lot of acid in it because the pipes might have a layer of corrosion on them before they are installed. You should never use plumbing solder on electronics.

The pipes themselves are fine. Clean them up however you like but if you use acid, rinse them thoroughly in water before attaching any electronics.

I think Air conditioning copper tubes are almost pure, but their surface might have an oxide layer so you must treat them with chemicals to remove that.

Emery cloth has also been known to remove such things. :wink:

I'm not re-using old filthy copper tubing from a junk-yard. I am just trying to find some copper tube to buy new from somewhere, that has close to inner diameter of 8 and 6 gauge wire. The smallest tube the plumbing supply store sells is over-sized 1/4" tube, and that's too big. I can't really find any common place that can sell me something useful. Now I have to go find a local metal supply store. I can order from Mcmaster, except the cost of the shipping doubles the cost of the 12" tube I need.

Hi,
Check the model live steam engine suppliers, they use smaller than 1/4".
You might get somewhere googling.

Tom.. :slight_smile:

Model engine tubing can be brass, so watch out for that, but should be obvious. You can buy copper
strip too, which might be useful.

Actually brass isn’t too bad a conductor, however its much less ductile than copper which limits
how much you can reshape it.

Battery lugs aren't that dear - and some are made of plated steel. But you can buy smallish ( 5mm) thickwall copper pipe in reels from motor factors as replacement brake pipe. Good stuff.

Allan

I was curious about the automotive brake lines too, and can’t get a scientific answer. The mechanics just replace brake lines and nobody ever asks about the copper, lead, aluminum content of the pipe. It’s soft enough for me to shape using hand tools.

DocStein99:
I was curious about the automotive brake lines too, and can't get a scientific answer. The mechanics just replace brake lines and nobody ever asks about the copper, lead, aluminum content of the pipe. It's soft enough for me to shape using hand tools.

The lines for hydraulic brakes that I have ever worked with are steel. Plated on the outside for corrosion control. They have to withstand tremendous pressure without expanding because your life may depend on them.

Copper tubing WILL expand in use if the fluid has much pressure at all. That is why you use new tubing for any plumbing using copper. Old tubing will be too large for brass fittings.

Payl

That's why replacement brake pipes are copper. Totally corrosion resistant and much easier to work - I wish all car makers used them from the start because we then wouldn't have the pestiferous job of replacing them after 10 years or so. Volvo did for a long while, but now don't - presumably because steel is marginally cheaper.

Brake lines run at up to 3000psi or so, and the copper stuff has walls > 1mm thick. Do your hoop stress sums and you'll find they have a >10 times safety margin.

Allan

inner diameter of 8 and 6 gauge wire.

I would be very hesitant to re-purpose copper plumbing for use on a crimped connection. There's a bunch of "black magic" to crimps, and I'd worry that the plumbing would not have the right ductility or hardness (or something) that could lead to loosening and dangerous conditions (for any circuit that needs 6 to 8g wire to handle!)

westfw:
I would be very hesitant to re-purpose copper plumbing for use on a crimped connection. There's a bunch of "black magic" to crimps, and I'd worry that the plumbing would not have the right ductility or hardness (or something) that could lead to loosening and dangerous conditions (for any circuit that needs 6 to 8g wire to handle!)

I'm my connectors for my prototypes, where they are checked, changed, moved, connected and disconnected all the time. It takes me about 15 minutes to cut a piece of copper tube, squish one end in a vice, and knock a hole in it with the drill press. It's stuck on the cable, then crimped with a 10 ton hydraulic die press.

It could sound petty - but money adds up. Build electric vehicles, the motors, batteries - then I go grab some connectors and the box is empty. I have to rush out to hardware store want to charge me $5.00 for ONE battery lug! OR I wait, order pack of 25 to get shipped, they come cost about $25, 2 or 3 more packs later is $75. 3 meters of copper tube cost around $12.00. Except no hardware store or plumbing sells any copper pipe / tube less than 1/4" - which is too big for 6 and 8 gauge wires to make a tidy crimp terminal. Metal and material supply want me to have accounts and place orders of hundreds of dollars, do not want to sell small supplies to people like me, where I prefer to see the prices online catalog - click & buy without dealing with sheister salesman to sell me a pallet of metal.

I finally found "MICROBORE" copper tube, for refrigeration has 6mm O.D. tube with 5mm I.D., is soft copper.