Tinning your own lugs?

Iceni John · March 2015

Is there any reason that I shouldn't tin my plain copper lugs with a lead-free solder, at least just on their contact surfaces where they'll be clamped? I can't easily buy tinned copper lugs locally (even the West Marine here doesn't have them!), but I can buy decent-quality plain-copper lugs at several places here. I'm thinking that I could cover the top and bottom of their contact area with a lead-free solder before I crimp them on the cables. Does this solder oxidize appreciably? They won't be used on a boat or in a marine environment, and my FLA batteries are in a well-ventilated compartment to minimize acid fumes. After I've crimped them on (I've ordered an FTZ 94284 crimper which will be here next week - yeah!), I'll use some thick adhesive heatshrink on each lug.

Has anyone here done this to their lugs?

John

mike95490 · March 2015

For you to tin them, they need a "witness hole" near the front of the lug, to let flux gasses escape. But I would suggest you tin them with REAL solder, not lead free.
I had to tin my own adapters, polish inside & out, flux and tin in plumbers lead pot, Clean flux residue COMPLETELY, plumbing flux is acid flux, and will ruin electrical work. See my Big Lug link in my .sig

Iceni John · March 2015

mike95490 wrote: »

For you to tin them, they need a "witness hole" near the front of the lug, to let flux gasses escape. But I would suggest you tin them with REAL solder, not lead free.
I had to tin my own adapters, polish inside & out, flux and tin in plumbers lead pot, Clean flux residue COMPLETELY, plumbing flux is acid flux, and will ruin electrical work. See my Big Lug link in my .sig

I don't want to tin the entire lug, just the upper and lower faces where it is clamped through the stud's hole. I was thinking of using a plumber's torch or even my hot air gun (I've used that for soldering MC4 connectors), not dipping the entire lug into a solder pot.

Why lead/tin solder? I thought that it would oxidize more than "lead-free" solder (which is mostly tin, with a few percent of other elements). I've seen old joints made with lead/tin solder that have oxidized badly when exposed to the weather.

Thanks, John

706jim · March 2015

Many years ago, I worked as an electrician installing wiring harnesses and lights in transport trailers. When I would go "upstairs" to pick up a harness, I noticed that they had a pot of molten solder that was heated 24/7.
Have to wonder about lead fumes in that environment.
But it was great for tinning lugs.

Photowhit · March 2015

If it's something you want to do, do it. I personally don't believe you can't find tinned copper lugs in Southern California.

You have a West Marine? get off this forum and go there, Here's a link! Buy them and have them shipped to your store for free. I won't check for you but I'll bet dollars to donuts, you can get an(any!) auto parts store to order you some. I use to work at a battery store if we didn't have the correct lug (usually because we were out)we sent people to NAPA.

mike95490 · March 2015

Solder pots of molten solder, do not create lead fumes. Some vapors from the flux for sure, but you have to heat way past melting to get to driving lead fumes off the molten metal.

And the inside of the lug, where the wire goes, should be tinned too, since it inhibits corrosion more then the bare copper. But in So Calif, there should be off the shelf tinned everywhere.
Pure tin has some interesting, bad properties when thermal cycled. Tin "solder" has killed several spacecraft. Lead lasts many years in mid-evil stained glass and roof flashing,
Tin has to be electroplated to copper, solder will fuse to it. It's not a good plumbing joint either, but just like lead-free solder is NOT solder, lead free brass, is NOT brass either. It's something else, that behaves differently,

Iceni John · March 2015

Thanks for your replies. I didn't know that West Marine had the Free Shipping To Store deal - for less than a buck more than I paid for plain lugs it's not even worth me faffing about trying to tin my own lugs. I know Ancor lugs these days aren't the very best quality, but they're more than good enough for what I'm doing, and they'll still be much better than the crappy mismatched poorly-crimped lugs my bus now has (I'm guessing that the school district that owned it used whatever they could when they had to replace cables, because there's no way that Crown would have made them that way originally!).

Good point about tinning the insides of the lugs. I was just thinking about the contact faces, but that wouldn't help much if there were corrosion between the cable and the lug! I'm hoping that a good solid crimp all around the circumference to make a "gas-tight" connection will give me cables I won't have to replace ever again. Do you use any type of anti-corrosion paste or goo inside the lug before it's crimped, or do you crimp them dry?

Thanks, John

PS - Just ordered the lugs through West Marine. My new crimper should also be here soon. Guess what I'll be doing next weekend . . .

mike95490 · March 2015

I use a copper loaded grease from McMaster Carr industrial supply. The grease will flow into the strands and up the cable, sealing it much better than heat shrink w/glue. Where the crimper applies pressure, it nearly cold welds the wires and lug, but you crimp in the middle of the lug, not the end, so the wires at the end still have exposed strands.

Iceni John · March 2015

mike95490 wrote: »

I use a copper loaded grease from McMaster Carr industrial supply. The grease will flow into the strands and up the cable, sealing it much better than heat shrink w/glue. Where the crimper applies pressure, it nearly cold welds the wires and lug, but you crimp in the middle of the lug, not the end, so the wires at the end still have exposed strands.

Thanks for that tip - I'll look for something like that.

Oh yes, I got my crimper today. Wow! It's serious. 25" handles, 5 tons of force, rotating dies (using the same die sizes as the way-more-expensive AMP crimper), able to correctly crimp all sizes of thin-wall and thick-wall lugs, pretty darn good quality. So now I've got no excuse to make crappy cables! Now just waiting for West Marine to call me to say my lugs are in. I can use the FTZ for larger lugs, and the Harbor Fright hydraulic for smaller lugs, both of them making good circumferential crimps (provided you ignore the HF's fictitious AWG sizes on its dies!).

John

zoneblue · March 2015

For anyone wondering about what Mike was saying about tin, see eg this

http://www.aviationtoday.com/av/commercial/System-Design-Death-by-Tin-Whiskers_76599.html

Those tin whisker problems are obviously more of an issue on microelectronics than lugs. In decent quaility MC4s they use silver plating. Im not sure what "tinned" lugs are plated with, i thought it was just tin. Nickel is some times also used.

BB. · March 2015

Silver migration was a problem with early electronics (silver plated IC Leads):

http://www.ami.ac.uk/courses/topics/0158_emgr/

Silver is the metal most susceptible to migration, since it is anodically very soluble and requires a low activation energy to initiate the migration process. Copper, zinc, and lead will also migrate, although only under much more severe conditions. Most other common electronic materials are not susceptible to migration: iron, nickel, and tin because of their low solubility in water; gold, platinum, and palladium because they are anodically stable.

Note sure this is as much of a problem with crimp lugs vs fine pitch electronics on a PCB.

-Bill

mike95490 · March 2015

I mentioned Solder vs Tin, because heat will not fuse tin thoroughly to copper. Solder (tin/lead) is a very special thing, that has marvelous properties. Then some enviro wackos saw the word "lead" and decided to ban it, and problems are arising from it. Even if 5% lead is added to tin, it makes it much more feasible and longer lasting.
(added) Pure tin for plumbing connections and to coat copper lugs is not truly possible unless it is electroplated on. Molten tin on copper has many voids & flaws. Frankly, I don't understand how tin copper plumbing joints don't just blow apart in the first minute !

cngedele · August 2018

@ Iceni John

I didn't try this But i also interested to know about it.

www.cngedele.com

Tinning your own lugs?

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