Battery Pack Tabs

No.

Bob

YEE-ikes!! And double yikes! Acid core solder is intended for plumbing, auto radiators, leaded glass and the like, **never** for electrical or electronic applications due to its corrosiveness. Never heard of using it for connecting batteries unil now. With immediate, scrupulous cleanng one might get away with it. But you'd still hafta wonder how much acid wicks its way up under insulation and remains. Bob, do you solder anything other than the tabs themselves with acid? What about the lead wires? One might be successfully using it, but for the sake of newbies, don't suggest acid solder for anything outside its intended use. Please. Merry Christmas !! Bill (oc)

P.S. When laying out cells for making a pack, I always burnish the tabs with sandpaper first. Very important. Then secure the cells together mechanically before making the electrical connections. The burnished tabs accept rosin solder with absolutely no problem, and make thin, secure connections, leaving no excess globs or lumps. Burnishing first is the key to good flow and adhesion. Bill (oc)

Enjoy...

It would take 3-4 weeks to do any real damage to the wires or tabs. Ammonia or soap instantly neutralizes it, thus the Windex.

I solder everything except electronics with acid core. It holds 2x better, and wicks 10x better than rosin core.The solder lays down flat, and this makes it very easy to solder glob free.

I strongly disagree. Acid core is 100 times more newbie proof than rosin core. Rosin core is fine for skilled soldererererers, but even then it's not worth the extra care one must take to do it right.

My detailed studies have shown that 10 newbie soldering failures out of 9 are due to globs and poor tinning (alloying) and adhesion/cohesion. I have never seen an acid flux induced failure. I admit I have seen some corroded wires because some doofus obviously didn't wash the flux off. That's human error, just as soldering globby is human error.

That acid will not kill you. It's not raw chicken. Just solder, wash, and go fly. Be sure it's in that order, and everything will be fine as frog hair.

I once ran the QC department in a large appliance manufacturing plant. We soldered EVERYTHING with acid flux, even switches and thermostats with PC boards. But guess what? We rinsed everything we soldered. Rinsing will not kill you. It takes 10 seconds. If it's that repugnant, get your wife to do it for you.

In electronics, corrosion is a slightly greater danger than mechanical failure. In all other applications, the opposite is true.

Bob

You are a skilled solderer. Good on you!

Oh yes, "experts" have told me to never get sandpaper within a mile of a solder joint. But I've done the same thing as you. After a lot of practice and thought, I rather let the acid do it for me.

Failure to clean a finished joint (regardless of flux used) causes more failures than almost any other bad solder joint problem you choose to notice. Rosin will become the site of all sorts of unpleasantness if it is not cleaned as Bob does with acid. The only thing is one MUST dry the site after you 'flush' it.

Fodder for the fray. . . .

Sheppard)

That's because if you look _really_ close, like with a scanning electron microscope, you can see chunks of silicon in the scratches made by the sand paper, and of course not much of anything sticks to silicon except silicon. Aluminum oxide do the same thing only worse because of the 'oxide' part.

It's only a minor contaminant, not a show-stopper, but purists have a fit over nitty-picky things like that.

Just to throw more fuel on the soldering heresy fire, I've been making up model control system linkages for decades using RS rosin-core solder. Never had a failure, never had a bad joint, and I can get the stuff on weekends when the welding supply houses are closed.

Given the chance I'll snag a pound or two of J.W. Harris' solid wire solder, but that stuff is about as common as chicken lips these days.

Took me four hours this morning to change an R-22 compressor in a 30 degree, 20-knot wind. Had a bit of fun keeping the joints hot enough to get the 15 percent to flow without cooking it brittle.

Getting silver solder joints right in those conditions takes a goodly bit of practice, but simple hobby solder joints ain't rokit siunse.

I'll chime in on the "newbies should follow the rules 'til they know better" ballot.

If ya want a hobby soldering challenge, try building the landing gear for a Balsa USA 1/3 scale Cub. Soft solder joints on top of silver solder joints in a mix of steel tube, brass tube, and steel rod.

APITA, but it's dead-scale if done right. Cheers, Fred McClellan the dash plumber at mindspring dot com

Sheppard)

It's ok to leave bits of a insulation behind, but not ok to leave bits of conductor behind ?

It's better to leave minute traces of silicon behind than to leave minute traces of oxide ?

What's wrong with this picture ?

If anything, "emery cloth" would be preferred because it is conductive to a degree, and we're talking about making up electrical joints, here.

_neither_ is technically correct, but neither leaves enough residue to prevent the solder bonding or the joint working as desired, both from a mechanical perspective and an electrical perspective.

Cheers, Fred McClellan the dash plumber at mindspring dot com

On Sat, 20 Dec 2003 06:23:22 GMT, Fred McClellan

You obviously do have a newbie problem like I do. They bring stuff to the field that's half-assed done, and it takes up all my flying time re-doing their handy work. They ask me to fly and wring out their stuff, and that puts me in a terrible position. If their solder joints are not good and it causes a crash, I am the bad guy. There is rarely any proof as to what actually causes a crash.

Even a newbie can make acid core solder flow and adhere. It takes a good hand to make rosin core work on stressed joints. I can do it, you can do it, but a green-assed newbie usually cant.

You can look at micro-crap with a SEM while I look to get a newbie model down in 1 piece. It's nit-picking vs survival. *

Tip for ya: I use .023 steel MIG welding wire to wrap LG. It's copper plated, and acid core wicks into it great. The wire has great tensile strength, yet is just soft enough to wrap tightly and uniformly. Use a 500w iron, and don't spare the flux. If wrapped correctly, the wire does way more than the solder. If solder is relied on for structural strength, it will always fail.

I think it makes absolutely no sense to wrap a highly stressed steel joint with soft copper or brass wire. I get really frustrated when someone brings stuff like that to the field and it collapses and takes up everyone's precious winter flying hours.

Bob

My point exactly on the acid core solder. Sometimes we overlook practicality for a technicality.

Bob

Wasn't picking nits, I was responding to the expert who insisted that sandpaper is good and aluminum oxide is bad for preparing electrical surfaces for soldering.

Unless one is welding something like 17-4 primary coolant piping, the choice of abrasives is a don't care from any practical standpoint. There are undoubtedly other applications where the abrasive used is critical, but model airplane solder joints is certainly not one of them.

I've never built LG where wrapping and soldering was a viable option, but that's because I only have one wire-gear model, a .60 trainer with which I beat newbies over the head.

The L-4 (Cub) is the only scale model I have with fixed gear; wrapping and soldering wasn't an option because it would be decidedly non-scale.

I want to re-shoot some of the photos on the web site because they were originally done with a Kodak PalmPix, not the world's best digital camera. Now that I have a decent digital rig, I'm going to re-do the fuzzy photos. The Cub/L-4 LG is still in the jig, so I'll shoot it too.

You might agree that wrapping wasn't an option if you look at the photos when I get them uploaded. With any luck (read : no more honey-dos today) I'll have those photos online tonight.

I spend a fair amount of my working day making up silver and soft solder joints, and I found the Cub/L-4 landing gear difficult to get right.

It is without question a project which soldering newbies need to have done while they watch.

No doubt wrapping and soldering is viable, I simply don't have any subjects amenable to that approach.

Cheers, Fred McClellan the dash plumber at mindspring dot com