Crimping Electrical Lugs

Derek hi

I used two 1/8" drive keys out of an old shaft in a vice too crimp an Anderson plug on my new Air Pressures, worked a treat.

Richard

My 2 bob worth..Ive been working as a sparky offshore for a number of years now. Any lugged cable that needs to operate in a place of high vibration and heat should be mechanically crimped.

>Solder is old technology.

Run that one past me again? :)

Mike Harding

A solder joint has both conductors totally enclosed in metal, so they are much more corrosion resistant. Using the corrrect technique will prevent solder wicking up the wire and cause loss of wire flexibilty. Correct use of heatshrink will prevent fatigue failure at the connector.

If you don't saturate a crimped joint with Lanolin Oil, and if any moisture gets in, it will start to corrode, and you won't know about it till it fails.

If you don't have the right tools, materials and skills then don't crimp.

If you don't have the right tools, materials and skills then don't solder.

I used to be a big advocate of soldering the larger lugs, but have changed my tune in the last couple of years.

A soldered joint can (and will) fail more readily than a properly done crimped joint.

The problem with soldered joints are twofold:

1). they have a tendancy to be so rigid that fatigue can affect them after a while and lots of vibration.

2). the tendancy for the joint to be "dry" is also a big concern. Basically, this means that although the joint "looks" okay to the casual observer, the bond on the inside of the joint can fail. This is more prevalent on PCBs, but can also occur on larger joins like you would use in an Anderson plug etc.

Not trying to start WWIII, but just stating my opinion and the fact that I have "seen the light".

Roachie

>If you don't have the right tools, materials and skills then don't crimp.

>If you don't have the right tools, materials and skills then don't solder.

I think that sums it up very nicely.

Additionally people - we have to keep in mind... we are not writing an instruction manual for technicians servicing a nuclear bomber. I have no doubt we could do extensive internet searches and find investigations into why crimping is "BAD" - no doubt similar searches would show why soldering is "BAD" - I seem to recall NASA decided wire wrap was the most reliable?

Once we've done all that we need to consider what Fred Smith with a Nissan Patrol really wants to do and whether he needs connections which will withstand military inspection or just wants to charge his batteries?

Mike Harding

"The problem with soldered joints are twofold:
1). they have a tendancy to be so rigid that fatigue can affect them after a while and lots of vibration."

- If you have insufficient heat available the solder will wick along the cable before it's heated the joint fully - this can be avoided.


"2). the tendancy for the joint to be "dry" is also a big concern. Basically, this means that although the joint "looks" okay to the casual observer, the bond on the inside of the joint can fail. This is more prevalent on PCBs, but can also occur on larger joins like you would use in an Anderson plug etc."

- This is easily avoided if you have the a soldering iron adequate for the job and the skill to recognise when the joint has been heated fully to avoid a cold-soldered joint.
- If you apply insufficient pressure to a crimp, it may also look ok but it will fail eventually.

Obee, if you have seen the number of faulty (fatigued) solder joints that I have then you would only crimp. It's not good trade practice to solder and that has been the case for many years now.

If I showed you the crappy "crimped" connections I've seen done by amateurs, you would realise the benefits of an airtight metal-to-metal seal in a PROPERLY soldered connection.

Gday Gronk
I think that your dad and mine are the same person.Mine could repair anything with a screw driver and a hammer,with pipe wrench on the side.
Murray

Ha ha.......even after saying all the "right" things to do regarding soldering etc......I have used the old hammer and screwdriver on a lug or two !!!!!!!

90mm2 cable.....hot joint....machine needs to be going ASAP.....no crimpers in sight.....out comes the hammer ........good enough until the next maintenance shift..

Gronk, It's not ok to solder if there is movement or vibration at the joint. Soldered joints fatigue and break, crimped do not. Solder is only ok on fixed (will never be subject to vibration) positions.

Kiwi Kia

You know what you're talking about with things electrical - that is clear from your past posts and I am interested in your statement above.

My background is in electronics design and electrical engineering and I don't have a lot of experience in the "longevity" or "service-ability" of components so I would be most interested to hear why you state that soldered joints are more susceptible to vibration than crimped joints?

My (lack of) mechanical knowledge implies that both cables would be constrained at the point of contact with the lug so I imagine any vibration of the cable would create stress at the constraining point and thus lead to possible fractures? What d’ yer reckon?

Mike Harding

Hi Mike, Yep, plenty of experience which i won't go into here. Wires tend to snap off at the point where they become stiff at the soldered joint when subjected to vibration. If you like, it's a part of a bending radius (which can attenuate movement) is suddenly stopped at a stiffened point. Instead of the stress being distributed across the cores it tends to become concentrated at a single point. Copper, instead of being ductile becomes solid at the soldered junction. Stress relieving of cables is avoided on pc bds by using plugs (with crimped pins) instead of soldering direct to the pc bd. Plugs are not always just for convenience of replacement. The flexible ribbon film with printed tracks instead of cable is an example here, little stress and very flexible which absorbs movement. It is illegal to use soldered joints on most electrical cable these days - crimp or clamps only. You would be VERY hard pressed to find a soldered joint in any machine, appliance, aircraft - whatever these days and that is no coincidence, it's for a very practical reason - soldered joints fail far more easily then crimps/clamps.

Would agree with most of the above, but my point was probably more about lug size ? If you don't have a lug to suit the size of cable, then you are better off soldering..

I've worked on assembling trains ( among other things ) and we always had a lug to suit the cable ( in fact you weren't allowed to use anything else ) but in some grey areas ( like an anderson plug !! ) the home handyman may not have access to different lugs or cables ??

If the cable ( and lug ) need to carry high current, then a crimped lug needs to be done right...not shoving a 16mm2 cable in a 25mm2 lug and using a crimper that flattens one side of the lug.......a hot joint can create more damage than a broken wire ( if you have 900A running thru a 150mm2 lug, then I'd rather fix a broken wire than a hot joint ? )

100% agree with you Gronk. Replaceing high current switch gear after a burn up ain't cheap ! (or easy work). But, you can get large clamp type lugs, you don't need to use crimps. Actually I don't like a lot of the small to medium size lugs as they don't seem to have a suffeciently large surface contact area around the bolt hole. The larger the hole the less strength in a very important part of the lug.

"You would be VERY hard pressed to find a soldered joint in any machine, appliance, aircraft - whatever these days and that is no coincidence, it's for a very practical reason - soldered joints fail far more easily then crimps/clamps. "

The reason you only see crimp in these situations is because they are controlled - the tools are controlled, the connectors are controlled, the techniques are controlled, the wires are controlled.

The question was about joining wires at home !!!

Saying that "only crimping is reliable" is a logical as saying "never join metal by bolts - you MUST use rivets for reliability - have a look at any aircraft body".

Mike, the problem is work hardening and then failure (fracture) at the solder point - not the electrical conection quailities. As I have mentioned previously soldering of terminations is ilegal in a 'power' context. This is not just an opinion of mine it has sound physical engeineering reasons behind it. I have never said that it (solder) does not work, it is just not 'best practice' these days.

Yep, good point.......take the lug ( might be the only one you do for 3 yrs ) and get someone to crimp it properly !!!!

Being a 4x4 site....and no doubt a lot of anderson plugs have been put on.....how have people been lugging them ??
I found that my 8mm2 cable was way too small for the lug, so soldering seemed the only way to go ??