It's not that we're flaming you, just that we've never seen a soldered connection failing due to fatigue.
I'll consider your warnings though, and hold the wires against the chassis to avoid stress on the soldered joint . No one likes cables dangling around anyway

 

Hi there,

The question of soldering vs crimping comes up a lot on forums of all kinds, even automobile sites of course because of the battery terminals and the like.

I was taught a long long time ago (too long ago) that crimping is better than soldering, but look at that statement:
"crimping is better than soldering".

That is clearly a 'blanket' policy that is somehow intended to cover all possible cases that can occur in real life, and we know that blanket policies rarely hold in every single case. THAT is how i came to the conclusion that the difference depends highly on the application and what technique was used for both types of connections.

We can have either type fail if they are not done right, or even if the wrong choice was made for the application. So first and foremost it has to be done right, and second the choice of crimp vs solder has to fit the application.

In vehicle battery terminal applications it is common to use crimping or a clamp type connector, and these usually work pretty good. Once in a while though we come across someone who wants to solder the wire right to the terminal, using high heat and plenty of solder because the wire is a heavy gauge and the connector is large. So the question becomes does solder work for this application, if done right?

The answer seems to be yes, and i think i know why. It's because so much solder is required to seep in between wire strands that after it cools it is so strong that it's almost impossible to break or pull out of the connector. Solder itself is a very weak material, so wires that are tacked down with a little solder can rip right off of what they are soldered to, but when the wire end is inside the connector sleeve and there is ample solder applied, it's so strong there's no way to get it to fail without some extreme conditions.
By extreme conditions, i mean high heat and strong forces. We do get heat and force inside the engine compartment, but it's not enough to do damage ot the connection. The solder fills up any spaces between the wire strands and between the strands and connector sleeve so its' very strong and takes a lot of heat to damage. Of course another extreme condition is when the wire has to flex back and forth. The soldered connection will fail sooner than the crimp every time, because the crimp can handle repeated stress like that over and over, while the soldered wire is very stiff where the solder ends and the bare wire begins, so each strand gets flexed back and forth and breaks sometime later. This happens a lot with alligator clips that are soldered without using that extra end crimp for the wire insulation. That also brings up the point that wire insulation has something to do with this too, but in #4 gauge wire the insulation has less to do with the crimp than the smaller gauge wires like #22 because the wire cross sectional area is much larger than the insulation cross sectional area with large wire gauges.

How can i be so sure? I've done this in the past. It was long ago, but i remember that back then i didnt know about that blanket policy so i soldered one of my battery terminals right on to the #6 or #4 gauge wire (cant remember which it was now). That was on a car with a big engine too not a tiny rinky dink import. It lasted for a long time and never gave any indication that it would fail.
It took a lot of heat though, a blow torch, and a lot of flux. The joint is heated up slowly and lots of solder applied so it can flow into the strands and fill the connector sleeve completely. I may have also used some steel wool jammed into the sleeve at one end to keep the solder from flowing out of the joint, but only enough to fill the end voids as i wanted it to be mostly solder. Got rid of the car a long time ago but it had nothing to do with the soldered connection.

 

It's not that we're flaming you, just that we've never seen a soldered connection failing due to fatigue.
I'll consider your warnings though, and hold the wires against the chassis to avoid stress on the soldered joint . No one likes cables dangling around anyway

Exactly! Technical disagreement is not flaming.

If a connection is being flexed enough to break a properly made solder joint it will break a properly made crimped joint just the same. They're both solid physical connections after all.

Also every battery lead made with the standard lead lug ends is soldered on being the lead is melted right into the copper wire.

 

Exactly! Technical disagreement is not flaming.

If a connection is being flexed enough to break a properly made solder joint it will break a properly made crimped joint just the same. They're both solid physical connections after all.

Also every battery lead made with the standard lead lug ends is soldered on being the lead is melted right into the copper wire.

Hi there,

Sorry to disagree, but a crimped joint handles back and forth flexing better than a soldered joint. The soldered joint is more stiff and so the strands break one by one. See the post just before yours where i had addressed this issue. This is one place where crimp beats solder.

 

Aren't they extensions from a lead plate current collector?
Anyway, I plan on soldering a connector to the cable, not the battery lug. Though I may do it some day just to try...

 

Hi there,

Sorry to disagree, but a crimped joint handles back and forth flexing better than a soldered joint. The soldered joint is more stiff and so the strands break one by one. See the post just before yours where i had addressed this issue. This is one place where crimp beats solder.

Is your vehicle battery rolling around the engine compartment unimpeded with it's cables pulled tight the whole time?

Maybe in a high mobility application like an umbilical or tether cord where the cabling is not able to be properly supported at its ends it could happen but on a battery connection I can guarantee that if you have enough movement to break off a soldered battery cable the battery's own terminal will go first!

As I and others have pointed out many of us have been doing it for decades now with zero real world failures in properly done applications.

I am curious as to how you figure a properly done crimp does not in fact hold every single strand of wire solidly in a fixed position like a solder connection does? Do explain.

 

@tcmtech I wanted to quote your previous message in my last post, though it looks like I failed on doing so...

This part: "Also every battery lead made with the standard lead lug ends is soldered on being the lead is melted right into the copper wire"

 

Also every battery lead made with the standard lead lug ends is soldered on being the lead is melted right into the copper wire.

As someone who worked where they made battery cables, Delphi/Packard Electric, this is a misleading statement. While the ends were/are lead they are not "soldered" as we know and use the term "soldered". The lead is cast in a mold around the wire. The part of the mold holding the actual wire(around the insulated cover) is water cooled to prevent the lead from wicking up into the wire strands. The striped end of the wire is Slightly flattened or spread out to allow the lead to enclose the individual wire strands more effectively. No flux is used when the lead is then injected into the mold cavity under pressure. The actual bond between wire and lug/terminal is more of a mechanical than soldered.

The inspection process after molding is to make sure it meets a minimum pull test and a bend test close to the junction of wire and terminal to make sure the lead isn't wicking into the wire, under the insulation.

 

Interesting. I was under the impression they were melted together all the way though like a normal solder joint being I have never cut a good one open to look.

But that does rather explain why so many lead battery cable ends eventually corrode and have the cable come out.

I've been doing a bit of reading and research on the crimp Vs solder issue and it appears that for stationary relatively clean environments the crimp method is preferred due to the speed and ease of application.

However for real world harsh environments where high temperature swings and corrosive liquid or vaopors are likely to be encountered such as in automotive use crimp is only used in well protected weather tight locations like wiring harness connectors but for more open applications battery and starter cables solder has been found to be of superior for long term durability being the actual conductor or terminal material will corrode away and fail before the solder joint material itself will.

When properly done and used in normal range conductor flexing application both are equal but in excessive outright conductor bending events crimp comes in at marginally better most of the time.

Now as for the average DIYer solder is by far the most commonly accepted practice being the crimping tools to do proper crimp connection of any wire or cable size cost far more than a good soldering gun or small propane or butane torch.
A good quality reliable hand crimper for 10 ga and smaller wire will easily set a guy back $50+ and a large unit for doing actual battery cable in the 2 - 4/0 gauge range would put a guy back $300 - $400+!

Personally I see it as being a bad solder joint (cold soldered) can usually be remelted cleaned up and redone properly where as a screwed up crimp you have to cut off and start over which you only get so many redos before your wire or cable becomes too short!

As for who uses what, Well, from everything I read and watched it would appear that Aeronautics, Aviation, Military, Heavy industrial, Commercial and Automotive all use both depending on the specific application so there is no single 'one is better than the other' except for harsh potentially high weathering and or corrosive environment applications where properly done and sealed solder joints are prefered simply due to practical experience showing them to generally hold up better to weathering and corrosive effects than an equally well done crimp.

So from that either is good but price and realistic working condition are key to what will hold up better in any specific application. At the hobby scale the only difference comes down to who does theirs wrong better while using the wrong methods and tools for the job.

 

Wow, you really got into the topic! Nice investigation.
As I mentioned when starting the topic, my main concern is indeed the weathering and corrosion of connections. The question being more towards what soldering gun power to use or what soldering method than whether to solder or crimp...
Fine dry dust, high wind speeds at ground level, oil, diesel, mud and battery acid cripple bolted connections within a year here.

This is the kind of connectors that i can get here, though heftier, of more solid construction. Most starter wires are about 4/0 gauge (~12mm diameter) though some are larger, as cold cranking a diesel takes a whole lot of amps.

 

as these connectors are so unsuitable for the working environment, I want to get a better one and solder it on so as to forget about it for a few years.

 

Wow, you really got into the topic! Nice investigation.
As I mentioned when starting the topic, my main concern is indeed the weathering and corrosion of connections. The question being more towards what soldering gun power to use or what soldering method than whether to solder or crimp...
Fine dry dust, high wind speeds at ground level, oil, diesel, mud and battery acid cripple bolted connections within a year here.

I like to debate and win.

Technically for most large cable applications I use a combination method of moderate crimp with a full solder overlay followed by a either a heat shrink tube or red/black colored vinyl tape cover.

One of therese is great and well worth the $20. https://www.amazon.com/Forney-57637...477066495&sr=8-1&keywords=hammer+crimper+tool Requires a 2 - 3# hammer and basic sense to work properly.

For the cable battery connection ends I use these, https://www.napaonline.com/napa/en/p/GRO849056/GRO849056 , and I get them from Napa for ~$25 - $50 for a box of 5 depending on the size and design.

And for the other ends something like this, https://www.napaonline.com/napa/en/p/PHI82115/PHI82115 or this, https://www.napaonline.com/napa/en/p/NW_728134/NW_728134 .

As for cable size on my equipment I go with 6 ga for lawn mowers, 2 ga for I4 and V6, 0 for the smaller V8's,1/0 for the bigger v8's and V10's, 2/0 for single battery diesels and 4/0 for dual battery diesels and have never had problems from that.

 

45 watt caliber weapon of mass construction.

 

Is your vehicle battery rolling around the engine compartment unimpeded with it's cables pulled tight the whole time?

Maybe in a high mobility application like an umbilical or tether cord where the cabling is not able to be properly supported at its ends it could happen but on a battery connection I can guarantee that if you have enough movement to break off a soldered battery cable the battery's own terminal will go first!

As I and others have pointed out many of us have been doing it for decades now with zero real world failures in properly done applications.

I am curious as to how you figure a properly done crimp does not in fact hold every single strand of wire solidly in a fixed position like a solder connection does? Do explain.

Hi,

I had a feeling you were going to ask that question

What do you think, it's magic or something? How would a crimp ever be better than a soldered joint?
This is definitely not a new question and i know it was asked as far back as at least 1980 and most likely long before that. Ask yourself how long you have looked into this and how hard you looked.

First, it is not always better, sometimes it is similar, depending on the application.
When it is better, it is because a crimp is not a single mechanical support structure like a soldered joint is. It's a much more complex structure. That means the analysis has to reflect that in taking several things into consideration, some of those things helps the joint in a way that just solder never can.

First, solder is a single interface. There's solder, and that's it. It interfaces with the wire strands and the connector sleeve. That's it. When you try to bend the wire near the joint where the wire meets the solder, the micro movement is abrupt and disruptive to the wire metal because it can bend at such a sharp angle. This is similar to how we can fold a piece of paper sharply in order to get a nice clean rip when we rip the paper in half. We get a fairly nice straight rip where we folded it. But what if we folded it over the corner of a table that had the top edges routered into a nice round curve? What would happen to the paper when we tried to rip it at the fold? It would rip in a jagged way because the stress is now distributed along a wider cross section. That's where we see principle #1 come in: tha angle of the bend affects the distribution of the stress where the wider the angle the better the stress is distributed over the material.

Now in addition to that, lets say that we also add a support. A support to keep the paper from bending at the edge. That supports the paper at a distance that is away from the edge of the table, which helps to stop the paper from bending in the first place, at least at the edge. That's principle #2 in action.

Now lets say that in addition to using a table with a smooth edge curve, we also add padding. We get some foam and apply it to the edge of the support. Now when we fold the paper over the edge, we get a very large bend radius, and the paper is cushioned so the stress is distributed over an even larger area of the paper now. We'd never get a nice clean straight rip in the paper now because the force is distributed over a very wide area. That's principle #3.

So already we have three principles at work in trying to rip the paper with a clean edge:
1. The angle of the dangle.
2. The support of the material.
3. The padded added as an interface between the paper and the support.

Now lets see how this applies to a wire in a connector body that has a crimp and one that is soldered.

1. The first crimp occurs with the bare wire, the stress angle is the angle from the wire in the crimp to the wire outside of that first crimp.
2. The second crimp occurs with the insulation on top of the wire. That is a distance away from the bare wire crimp so the stress angle is reduced.
3. The insulation acts as padding to help keep that part of the wire from being stressed. Indeed it can not be as bad as the first crimp if there was no second crimp.

So there we see three mechanisms in place, where with a purely soldered connection we have only the one angle which can be as sharp as it can be given the amount of flexing of the wire. In other words, the angle will always be sharper than the crimp, and we know that sharp angles are no good for the wire durability similar to the paper fold. In fact, you can fold the wire with a solder connection at a 90 degree angle, while with a crimp you cant do that because the most stressful part of the crimp is mechanically separate from the wire (the first crimp).

Now sometimes the insulation will not act as much as we would like to help reduce the stress, but it's always at least doing a little bit. How well ti help depends partly on the ratio of the thickness of the insulation vs the thickness of the wire. With thick wire and thin insulation, it wont help as much as with thin wire and thick insulation, which would help a lot. Also, thick wire doesnt need as much padding as thin wire because it naturally has a wider bend radius.

This cover the main points of the difference, and to recap the important principles at work:

1. The allowed angle of the bend during flexing.
2. The reduction of the angle with the second crimp.
3. The padding due to the insulation layer.

Note these will be a little different for each application. In the automobile there should not be as much difference because of the above, however with thinner gauge wires there will be a lot of difference.

I can also show ways to reduce the stress even more, but it might turn into a patented product so i dont want to reveal too much info just yet.

If you have more questions or doubts that's fine. We can talk about them also.

 

Without entering the to solder or not debate, I'd just say that when I have a soldering job too big for the available irons I usually use a "cooks blow lamp" Google it if you don't know about them..In the case of battery connectors use close fitting crimp terminals, put some wet cloth around the adjacent insulation, set upright in a vice and heat the lug. I have found them so handy I keep one in the workshop..

 

Hi there,

Well it is good to hear from individuals like you as that allows us to compile a list of what actually HAS worked in the past and what actually HAS NOT worked in the past. That coupled with the application, we get a good comprehensive list so other people can check it out and know what to do right off the bat.

Back when i worked in the industry we got instructions from one of the major military aircraft companies that crimp terminals were mandatory in any equipment made for them. They would not allow soldering because of the problems that came up over longer periods of operation.
One of the problems i remember was that the finished joint is very hard to assess as to how well it was done because we cant see inside the joint once it is soldered. I've seen this happen a few times myself, where the connection looks good but there are air spaces inside the joint that we cant see. The crimped terminal allows for a more comprehensive inspection, and believe me, they always sent their most strict inspector who demanded tests that had to follow very strict guidelines and use specific brand name test equipment. One of the nicest guys i ever met, but he was strict about the quality of the product which is understandable considering the importance of the application.

 

don't know if it still applies, but at one time the only time a soldered joint was allowed in FAA rules was the interface with the avionics/instruments. The electro-mechanical connections were crimp only. With that said, the crimps had to be done in a terminal press, not with a hand held crimper. That changed for maintenance type work with the advent of "ratchet" type crimp tools, tools the had to be squeezed to a certain pressure before the could be released from the work.

 

Back when i worked in the industry we got instructions from one of the major military aircraft companies that crimp terminals were mandatory in any equipment made for them. They would not allow soldering because of the problems that came up over longer periods of operation.

As someone who has been around military surplus gear all my life I have seen the military use both, a lot. One specific device will be all crimped connector. the next one all solder. I have examples of both covering gear from the ~1940's to present 2000+ year range.

I rather suspect it has more to do with the engineers who design the equipment than anything else being with a bit of searching and reading on the subject you can easily find first hand accounts form people who say they worked in every place I listed that say they did both depending on the application and design spec.

AS I stated before. It all comes down to the application. Each has it merits and drawbacks. As far as mechanical resistance to conductor bending moments I find that if any connector is being subjected to the degrees of movement that will break a solder connection it will also break a crimped on as well. It may take a few more bending events to do it but it will break just the same.

There's even youTube videos on that subject. On even one to one cyclic bending tests the solder joint wires broke off first but the crimped ones were well beyond torn up and looking pretty ratty do to having a large percentage of their conductors broken as well.

Personally I don't own any high end crimpers and have no reason to being my personal experience for the work I have ever done has shown that solder joints are more than sufficient. If something I build or repair has the conductors being bent so far so often as to break a solder connection off obviously I failed to properly support and anchor the wire to begin with to which in regards to the thread subject if battery cables are being regularly bent that far at the terminals there are some other major issues that need to be addressing in the system layout first.

 

Hello again,

In closing i'd just like to say that the right kind of crimped connector sails over solder in many cases. We can compare the crimp to a cord with and without a strain relief. The cord with the strain relief lasts longer because the bend radius is wider.
It does not take much to imagine how this works and why crimps are used. It's a simple concept but there is more to it than a solder joint.

I could show diagrams that clearly show that anything other than just solder is better because there is more strain relief inherent in the design. The soldered joint always has ONE point of stress, which is fairly sharp, while with a crimp we get a soft point of stress which has to work better. That's why humans use pillows instead of bricks to lay their head down when they go to sleep. That's why we sharpen our knives, to get the stress concentrated along a narrow line, while a dull knife distributes the stress over a wider area and so it's harder to cut through anything including copper.

 

You crimp yours and I'll solder mine and everyone else can decide what they like for themselves.