Crimp, solder, both?

[David WE Roberts]

Just assembling my 12V battery cables for the camper.

External diameter of copper cable inner is around 5mm. Internal diameter of connector (ring terminal) is nearly 8mm. So not a tight fit.

I was intending to crimp - not sure now if I should cut a slot in the tube to allow the connector to crimp down further or just flatten it out to get a grip. Looks as though it has been folded then welded/brazed shut so I would be undoing this last bit. As it isn't as snug as I was expecting I am now wondering if I should run some solder in as well. Just solder doesn't look as though it would give a secure enough joint - and I've never soldered multi-strand wire this thick before.

Items are

item

070907 and item 010601

Cheers

Dave R

[dom]

Step 1 - Buy the right terminal - one that fits closely.

With a fine multistrand cable like that, I would crimp (with the right terminal, and a heavy duty tool), and possibly solder as well (if I had a hefty enough soldering iron).

[Frank Erskine]

You could sleeve the wire with a very short bit of 8mm "microbore" copper pipe. The whole lot should crimp up better.

[Dave Plowman (News)]

Easier to use a small blowlamp.

[Peter Parry]

With the right tool and matching crimp and cable a crimp connection will almost always be more secure and reliable than a solder connection. This is especially so if the joint is exposed to vibration. Adding solder to a good crimp joint reduces its reliability.

[tony sayer]

In article , Peter Parry scribeth thus

Why should that be?. Not that you'd what to do both normally;!...

[Dave Plowman (News)]

Try making a solder connection to a terminal that can be crimped and a second crimped one. Flex the wire until it breaks. The solder one will do so much sooner.

[Bill]

In message , tony sayer writes

If you tin the wire first and then crimp, the solder has a habit of creeping over time and loosening the joint.

If you solder to the crimp tag then you have a solid firm joint that with vibration/movement may fracture.

With just a crimp there is a bit more flexibility at the junction of the cable and crimp.

I'm sure someone will be along in a while to give a better explanation, I have seen it discussed here before.

[geoff]

In message , tony sayer writes

Reduced flexibility, individual strands are liable to break away

I remember there was a long discussion here years ago when {what was his name who worked for the BBC and rode a bike} brought up the discussion with regard to motorbike harnesses

[Peter Parry]

Firstly, many solder joints are not well done, secondly the solder wicks up the cable and creates a short rigid length of cable going beyond the neck of the connector. The heat partially embrtittles the cable and its insulated coating and the wire breaks more easily at the "hard spot" at the sharp solder boundary. In addition the flux can cause corrosion.

Almost the only reason for failure in crimp connectors is the use of incorrect tools such as the silly pliers supplied with cheap crimp kits. You even get some people trying to attach crimp joints using pliers or wire cutters.

For high current (several hundred amp) cables it is usually better to cut the wires to length and pay someone with the right hydraulic tools to fit the terminations.

[tony sayer]

In article , Dave Plowman (News) scribeth thus

Who said anything about destructive testing;?..

[tony sayer]

In article , Bill scribeth thus

Done both overt time and can't recall any failures..

[tony sayer]

In article , Peter Parry scribeth thus

Cannot say I've ever seen that happen.. Unless you deliberately mistreat joints..

Indeed as you get "iffy" soldered joints;!..

Yes a decent crimp like a decent soldered joint and I've seen enough bad ones in my time!..

So the only failure is that the solder might creep up the cable and cause a fracture, no other reason then?..

[The Natural Philosopher]

He has it aright. Maybe you have done static installations. I've done a lot of R/C and a fair bit of mobile kit. Yes, they can and do fail where the solder stops.

the secret is to extend the support to the wire insulation upstream of the joint in some way. Heatshrink, epoxy resin.... and if you must use solder, use solder for the whole joint. Don't crimp soldered wire

[Nick Leverton]

I think Murphy usually does that bit post-installation !

Nick

[mick]

Got the wrong size crimps then? That sounds like 16mm2 cable to me, with (probably) a 25mm2 lug. Filling them with solder is never really satisfactory in the long term. It may be worth finding someone who will donate a couple of smaller crimps & fit them with a proper crimping tool.

[Andrew Gabriel]

Matthew Marks? Worked for BBC and used to do our FAQ, but I don't know about the bike bit.

[geoff]

In message , Andrew Gabriel writes

[David WE Roberts]

The link shows a 20mm^2 cable - so I assume it is this. The other link offers connectors up to 16mm^2 and up to 25mm^2. So for 20mm^2 I have to go for the 'up to 25mm^2'.

[tony sayer]

Mobile and static not aircraft tho;!. But apart from this solder wicking effect which might cause a mech fail if the joint was pulled around enough, don't seem to be any other failure mode does there?...