2 ga Cable/Wire Crimping

[Rzeppa]

X3 on Wes' and Stephen's recommendations. Crimp connections are fine up to around a couple amps on a non-critical application. Having been in electronics design and manufacturing for over 25 years, including over 15 years of quality assurance, I would NEVER recommend a crimp connection for that application.

A proper soldered connection will be many times more reliable and many times more efficient (from I2 losses calculation and measurement) than a crimp connection. They do not use crimp connections in satellites and other flight-approved and space qualified connections, you shouldn't either!

As Stephen wrote, you must preheat the connector (after sliding the heat-shrink up onto the cable, well past the heated area of course!), then tin it and the cable strands generously with rosen core solder. I use a propane torch for sufficient heat for 2 AWG to 00 AWG thickness applications, a regular solder gun can't make enough heat. Apply the solder to the cable strands at the interface between the connector and the strands, feed it in until it's filled. Wait until it's cooled to the touch, then slide the heat shrink over the exposed joint, heat and shrink. Voila! A mechanically and electrically sound joint that will last as long as your Toyota!

PS, while waiting for the molten solder to solidify, do not allow the joint to move even the slightest, or else you end up with a "cold" solder joint, negating the reliability advantages of a soldered joint over a crimped one.

 

[Seldom Seen]

They do not use crimp connections in satellites and other flight-approved and space qualified connections, you shouldn't either!

Humm....

SkyLab
Space Shuttle x2
Hubble
Rocket scientists who don't know the difference between feet and meters.
Last and by no means least, it was the electrical connections that caused the cryO-tanks to explode on Apallo 13

Yea that really inspires confidence

Crimping is good enough for Mr. Toyoda it's good enough for me.

 

[Red_Chili]

Ya, actually, I used to inspect crimp connectors on flight avionics for Peacekeeper and Titan missiles/launch vehicles.
Mind you, there were exceptionally well crimped, and I looked at them at 30X. But they were crimped.

 

[RockRunner]

Ya, actually, I used to inspect crimp connectors on flight avionics for Peacekeeper and Titan missiles/launch vehicles.
Mind you, there were exceptionally well crimped, and I looked at them at 30X. But they were crimped.

Bill, if you want I can find some of your old tested items laying around here They have so much crap in storage it is amazing.

 

[Red_Chili]

Naw, I saw all I needed to!!!
The funny part was, when LM (then, MM) contracted with Motorola to set up a line to produce transistors to 1960s standards - cuz that's what was qual tested! 5lb. 'NOT' gates, welded ribbon assemblies... antique row!

 

[Rzeppa]

I stand by my assertion that in this particular application, a properly soldered large gauge wire will be more reliable and have smaller I2R losses than a crimped one - mind you I am a big fan of crimped connections for certain applications, this just isn't one where crimped is better!

Several decades of failure analysis under my belt on this

 

[Uncle Ben]

I stand by my assertion that in this particular application, a properly soldered large gauge wire will be more reliable and have smaller I2R losses than a crimped one - mind you I am a big fan of crimped connections for certain applications, this just isn't one where crimped is better!

Several decades of failure analysis under my belt on this

For winching, starting and other high load applications crimp(swagged) is better! Solder will melt right out unless your using silver! With standard lead you will create a fusible link.

 

[Hants]

I don't hear any wizened recommendations for solder & crimping???

For winch & other high-amperage, heavy gauge situations, would solder (silver?) and crimping be recommended? I'm thinking get it hot, solder it up, crimp it while its still HOT.

In the marine world, they swear by crimping and using high-quality, sealing, heat-shrink. Would this be because it is more difficult to get a good solder joint? I've heard that mechanical/vibration failure is the big concern with solder-only joints.

Keep in mind that I have NO real-world experience with this, just a bunch of web & book lern'n.

 

[Uncle Ben]

I don't hear any wizened recommendations for solder & crimping???

For winch & other high-amperage, heavy gauge situations, would solder (silver?) and crimping be recommended? I'm thinking get it hot, solder it up, crimp it while its still HOT.

In the marine world, they swear by crimping and using high-quality, sealing, heat-shrink. Would this be because it is more difficult to get a good solder joint? I've heard that mechanical/vibration failure is the big concern with solder-only joints.

Keep in mind that I have NO real-world experience with this, just a bunch of web & book lern'n.

Crimp and solder would be fine. The key to any long lasting wire termination is heat shrinking! Solder (especially standard soft lead) will corrode in a moisture environment if it is not sealed. If you look at factory heavy gauge wire ends they are either swagged or molded but not soldered. When doing small gauge wiring connections the best (permanent) way is soldering and heat shrink sealing. The worse kind of connection is aluminum crimp connectors. The cheap aluminum used has very little memory and of course you are using aluminum on copper which is a catalyst for dissimilar metal corrosion. These standard type of crimp connectors are considered temporary or only intended for non critical connections.

 

[Rzeppa]

For winching, starting and other high load applications crimp(swagged) is better! Solder will melt right out unless your using silver! With standard lead you will create a fusible link.

For winching, starting and other high load applications SOLDERING is better. Solder will not melt unless it is subject to the heat caused by I2R losses from an improper connection.

A PROPER solder joint will ALWAYS have lower resistance (that's the "R" in I2R, it doesn't appear that the forum text editor will allow the superscript for the square sign) losses, resulting in less heat than ANYWHERE else in the circuit, including the wire itself.

When designing and building 50,000 watt laser power supplies, we were taught to always solder the 00 AWG, but a few engineers thought that crimping might save a few bucks when manufacturing thousands of units. After a few mishaps in the lab, it was empirically evident that the soldered terminal made virtually no heat, while the crimped ones melted and burned up.

Crimping is fine for certain types of low amperage applications, but for high amperage applications a PROPER solder joint is ALWAYS better.

 

[Seldom Seen]

that's the "R" in I2R, it doesn't appear that the forum text editor will allow the superscript for the square sign

I²R ?

 

[Uncle Ben]

After searching the web I will concede as all engineering experts seem to agree with what you say. I was always taught high amperage and soft solder were a no no. This is definitely your field of expertise so I will read and learn! In the early days we fixed alternators and starters in shop and we had to use high temp silver solder as a loaded alternator will "throw" soft solder in a heartbeat.

For winching, starting and other high load applications SOLDERING is better. Solder will not melt unless it is subject to the heat caused by I2R losses from an improper connection.

A PROPER solder joint will ALWAYS have lower resistance (that's the "R" in I2R, it doesn't appear that the forum text editor will allow the superscript for the square sign) losses, resulting in less heat than ANYWHERE else in the circuit, including the wire itself.

When designing and building 50,000 watt laser power supplies, we were taught to always solder the 00 AWG, but a few engineers thought that crimping might save a few bucks when manufacturing thousands of units. After a few mishaps in the lab, it was empirically evident that the soldered terminal made virtually no heat, while the crimped ones melted and burned up.

Crimping is fine for certain types of low amperage applications, but for high amperage applications a PROPER solder joint is ALWAYS better.

 

[Rzeppa]

Yeah, that's the one:

I*I*R=P=heat

Less R=less heat

In all due respect, it is not easy to get a PROPER solder joint on something like large diameter wire and a huge copper terminal without a fair amount of practice and experience. The result for someone who doesn't have a lot of experience in soldering may well be a connection worse than a crimp, which normally doesn't require as much expertise, resulting in larger R

WARNING! Proper application of heat shrink can also require some experience, and improper installation can actually make corrosion worse from gaps allowing moisture intrusion!

To whoever posted the question about crimping plus soldering: Storage Tech tried this during the 80s on their minicomputer power supplies that we used to build and saw zero improvement in reliability over crimped-only connections. These were applications that saw no adverse environmental conditions such as in automotive or other transportation related applications. They were also only in the 2-20 amp range so losses weren't as important as reliability.

To whoever posted about space-qualified reliability: No spacecraft with soldered connections have been lost due to failure of a soldered electrical connection. All of the examples listed were due to other causes.

There are many other engineering concerns in electrical systems besides whether a connection is crimped or soldered. Kevin's warning about aluminum is an example, but insulation material and thickness, wire routing, cable stranding, strain relief and many others must be considered in overall system design.

 

[Rzeppa]

After searching the web I will concede as all engineering experts seem to agree with what you say. I was always taught high amperage and soft solder were a no no. This is definitely your field of expertise so I will read and learn! In the early days we fixed alternators and starters in shop and we had to use high temp silver solder as a loaded alternator will "throw" soft solder in a heartbeat.

No doubt, that's a totally different application! A loaded alternator will generate tons of heat on it's own due to producing power and it's inefficiencies producing heat, just as any engine produces heat as an inefficiency from converting power. The heat is conducted to everything, including the connections inside the alternator or starter. It isn't the solder joint which is making the heat, but it is subjected to heat nonetheless and must withstand it, hence the silver solder, which has a higher melting point than convention alloys of tin/lead.

 

[Uncle Ben]

No doubt, that's a totally different application! A loaded alternator will generate tons of heat on it's own due to producing power and it's inefficiencies producing heat, just as any engine produces heat as an inefficiency from converting power. The heat is conducted to everything, including the connections inside the alternator or starter. It isn't the solder joint which is making the heat, but it is subjected to heat nonetheless and must withstand it, hence the silver solder, which has a higher melting point than convention alloys of tin/lead.

Sooooo....wouldn't the battery terminals under that same hood be subjected to that same heat? They would be very close to the 220 degree radiator, and the starter leads are most likely in close proximity to 500 degree exhaust headers. I've seen winch cable with melted insulation when the operator didn't know what they were doing and continued winching despite the smoke.

 

[Hants]

I think part of the concern with solder-only joints in automotive/marine environments is vibration & mechanical stress.

But, then again, I don't build military lasers or space gear... maybe they have the same issues?

 

[Seldom Seen]

No spacecraft with soldered connections have been lost due to failure of a soldered electrical connection. All of the examples listed were due to other causes.

Not yet anyway, given their track record, and the commonality of the thought process amongst every flavor of rocket scientist, it's only a matter of time.

I think it was the dOOd in Apollo 13 that said it best, "We are going to the moon sitting on top of a pile of parts sold to the government by the lowest bidder"

Anyway adding I²R instead of I2R to my searches yielded far more relevant hits. I have yet to find any source that backs Jeff's claim. Seems the debate as to whether a soldered connection has less resistance than a swedged electrical connection is akin to the debate between Gulliver's Lilliputians and Blefuscuans over whether to open an egg at the big end or at the little end. The argument may never be settled. The only thing that can be agreed on is the only sure way to decrease R is to increase the cross sectional area of the conductor and terminal.

I did find several sources that state soldering does NOT make an adequate mechanical connection in automotive apps. Soldering will not withstand vibration the way crimped connections will. As far as the heat situation w/ solder that UB pointed out "...for temperature cycling.. anything where there's a coefficient of expansion mismatch you can get little stress cracks leading to increased thermal and electrical resistance". When a lug is crimped on the process cold works the copper so the lug is actually welded to the wire making an incredibly strong connection. Think about how a hook is connected to a winch cable. I don't think any one would solder a winch cable.

Hants, I found one source the stated that adding solder to a crimped connection can actually weaken it. Solder can interfere with the copper bonds created during swedging. If the joint is tight very little solder will flow into the lug but it will be wicked up the cable, away from the lug, making the cable stiff and the joint less resistant to vibration.

 

[Red_Chili]

In the marine world, they swear by crimping and using high-quality, sealing, heat-shrink. Would this be because it is more difficult to get a good solder joint? I've heard that mechanical/vibration failure is the big concern with solder-only joints.

This is the method I used. Solid crimp on welding cable (not just 1/0), finer strands. Then meltable heat shrink. Then polyolefin heat shrink. Thoroughly sealed.

I'm thinking get it hot, solder it up, crimp it while its still HOT.

Not good. In MM solder school (based on NASA training) I learned just what such a joint looks like under 30X! If you are going to solder it, tin it, then crimp it, then flux it (with electronic flux, not acid flux used in plumbing ), then flow solder into the joint.

Solder will melt under very high current applications but only if the joint is ohmic (resistance due to corrosion or other causes).

 

[Red_Chili]

I think part of the concern with solder-only joints in automotive/marine environments is vibration & mechanical stress.

But, then again, I don't build military lasers or space gear... maybe they have the same issues?

Like none other.
Lots of crimped connections were used in flight electronics on the launch vehicles I inspected. Lots of soldered connections. But then they were potted. Everything was sealed, and everything was completely immobilized one way or the other.
I am satisfied with a solidly swaged, completely sealed connection. YMMV.

 

[Hants]

I'm back to where I started, then: welding/marine cable with swaged connectors and triple-seal heat shrink.

Now, where does one find a high quality mechanical-advantage (or hydraulic) swager for less than an arm and a leg? I'm talking the ones that are 2 feet long, not the hammer/vice/cold-chisel method.

Earlier in this thread, it was mentioned that West Marine has a work bench with a good swager... but the component supply appears sketchy.

I can justify in my mind affording the connectors & cables from West Marine if it saves spending $150+ on a swager that I'll likely only use once or twice in my lifetime. But going up there to find that they're out of supplies would be a big waste of time...