heat shrinking crimp terminals

[tobble]

I'm plotting the grand re-wire and have been thinking about terminals. In order to minimise moisture ingress into the cables (will be using tinned but I like belt braces, and safety pins) I am planning on removving the plastic insulator from each terminal, sliding a section of heat shrink over the cable, crimping on, soldering the joint so there's no path for air/moisture through the crimp, then shrinking the tube over the top to seal the cable outer onto the crimp.

1) Is this sensible or am I making way to much work for myself?! - I'm thinking the main effort will be in running the cables so won't add much time relatively speaking

2)Does anyone know what size heat shrink is appropriate for each of the red/blue/yellow terminals minus thier standard insulators?

 

[RivalRedwing]

1) seems like overkill
2) if you do proceed you can buy spade connectors without a plastic outer - have a look at vehicle wiring products web site (they do require a different crimping tool)

 

[nigelmercier]

I do exactly this, but I prefer to start with the non-insulated terminals, like these. I'd also suggest getting a selection of adhesive heat shrink, also from CPC.

The only problem I've had is I can't get male connectors for the smallest 2.8mm ones. Any ideas?

 

[Gin]

I tried this recently on one(blue) terminal which I had to replace and getting a tube small enough to shrink on the shank of the terminal was OK but it wouldn't stretch over the spade end, without splitting.

Conversely, a tube big enough to fit the spade end wouldn't shrink tight enough on the shank, so I gave it up as a bad job.

Perhaps you will have better luck, but have a try before buying loads

 

[nigelmercier]

[ QUOTE ]
Conversely, a tube big enough to fit the spade end wouldn't shrink tight enough on the shank, so I gave it up as a bad job.

[/ QUOTE ]

If you get 3:1 heat shrink (preferably with adhesive), it works just fine.

 

[Evadne]

A) You can get crimp terminals with heat shrink sleeving already applied.
B) You can also get glue-filled heat shrink, which is better at keeping the moisture out.

I can't give you the reference offhand, but I usually get everything via the web from either Farnell, CPC or RS so they should be in there.

 

[lw395]

If you use a good quality, probably ratchet action, crimp tool properly, then soldering is superfluous. Crimping, done, properly is more reliable on its own, in a vibration environment, as soldering may make the cable too rigid just beyond the terminal. Having said that, soldering is pretty much fine for a boat, if you take reasonable steps to secure the wiring. Its better than relying on an amateur crimp tool, imho. If you do go the heatshrink route, go for adhesive lined heatshrink, it seals much better. Make the heatshrink about 40mm long to provide some strain relief to the wire. How wet will your wiring get? On motorbikes, vulnerable connectors can be helped a lot by filling them with vaseline or silicone grease.
As you say, the extra time is small, it will pay off in ten years time. Get a decent soldering iron BTW, particularly if you're going to use dolphin-friendly unleaded solder! I would recommend a temperature controlled type, with a pretty hot bit.
HTH?
BTW you can buy uninsulated crimps!

 

[tobble]

The idea behind soldering them on is a) to improve both electricla and mechanical connection, and b) so that you don't need to stretch over the whole connector to seal it up, as there's no path down through the crimp.

[ QUOTE ]
I gave it up as a bad job

[/ QUOTE ]

To seal up the entire connection like this you could put a few layers of smaller heatshrink over the crimped bit to bulk it up so that you can then use the larger stuff to go over the entire connection. you might have more luck using bullet connectors rather than spades? but that to me sounds like more faf than soldering it up.

I'm glad at least one other person does the same,thanks for the tip on uninsulated connectors. still wating for a consensus tho...

ed: must type faster/think less...

yes, I remember hearing hearing soldering wasn't the best idea but couldn't remember the reason! but as you suggest vibration on a boat isn't the same asa motorbike for example... swings and round abouts... are there actually any examples of wire failing by fatigue having been soldered? Also idea of nice long HS for strain relief is good, and adhesive lined - thanks very much! re wetness - all the wiring will be inside apart from the mast, won't get wet per se. but in my experience, that doen't stop the bracing sea air bugring stuff up!

 

[Salty John]

I'd buy heat shrink adhesive crimp terminals and butt connectors and use a good quality ratchet crimp tool.
I'd be surprised if there was a more reliable joint even for wires lying in the bilge.
I think soldering is at best overkill and at worst makes the joint brittle, negating the benefit of multistrand wire.

 

[tobble]

I looked at these
merlin terminals but not sure they seal over the end of the wire, which is why I was thinking of soldering up the joint. Also slightly shocked by the price...

I'll email them and report back

 

[Salty John]

Here's another supplier:
http://www.davico-industrial.ltd.uk/catalogue.asp?id=7

 

[Ruffles]

[ QUOTE ]
I'd be surprised if there was a more reliable joint even for wires lying in the bilge.
I think soldering is at best overkill and at worst makes the joint brittle, negating the benefit of multistrand wire.

[/ QUOTE ]

Must admit I don't normally solder but I did when I replaced the earth bonding. Partly because the rings supplied by MGDUFF seem to be designed for it. Also with such small currents flowing the slightest resistance could be significant.

On the bonding to the gearbox tied the cable back to itself so any flex will be at the cable not the terminal.

 

[gandy]

And another ...

Vehicle Wiring Products

 

[rogerthebodger]

I put a squirt of marina silicone into the crimp terminal before crimping. This seals the cable end from the ingress of sea water.

If the connection is outside or in the bulge I also add some heat shrink over the top with silicone inside.

Adhesive heat shrink is not available in SA

Been doing this for the last 10 years on my previous boat without a problem

 

[Nigel_Ward]

I think if you use good quality crimps, professional ratchet crimpers and follow the instructions you will not need solder, heat shrink etc.

 

[rogerthebodger]

The main reason I use silicone is to seal the cable insulation to stop and corrosive sea water/salt air getting down under the cable insulation and damaging the wires

 

[Gin]

Thanks for the tip- I wasn't aware there was such a thing, I just bought a mixed size lot of heat shrink and none were adhesive.

You live and learn /forums/images/graemlins/grin.gif

 

[whipper_snapper]

I just got a bunch from Maplin. I specified adhesive lined, the invoice says adhesive lined. But the packaging for only one size says 'adhesive lined' not the rest.

So be careful with Maplin. I strongly suspect they are not.

In fact I took a photo to ask them before I opened them....Does anyone know ? Only the blue and red pack says adhesive lined.

 

[tinkicker0]

Back to that old chestnut. To solder or not to solder.

I personally only use solder on heavy battery tube terminals and wire gauges above 8mm2.

Interestingly, Honda Motor Company do NOT recommend soldering terminals on any wire subject to flex or vibration due to solder creep under the insulation adding a stress riser to the wire inner core, and subsequent mechanical failure of the core strands.

Honda engineers know more than I, so hence no solder on small gauge wires.
Avoid those horrible red, blue and yellow terminals though, use good quality dual crimp connectors with separate insulating boots and the correct ratchet type crimper.

If you do go down the solder route, use paste flux, not boric acid based products such as baker's fluid.
The grease in the paste helps resist corrosion.

And yes adhesive heat shrink is an excellent idea, go for a quality make with a shrink ratio of about 3 : 1 or better.

 

[LittleSister]

[ QUOTE ]


Interestingly, Honda Motor Company do NOT recommend soldering terminals on any wire subject to flex or vibration due to solder creep under the insulation adding a stress riser to the wire inner core, and subsequent mechanical failure of the core strands.

Honda engineers know more than I, so hence no solder on small gauge wires.

[/ QUOTE ]

I've a lot of respect for Honda engineering, having had a couple of their cars. On the other hand I used to wire equipment for the MoD/RAF and NASA (the American Space Agency, not the British cheapie boat kit firm!) and they specified soldering. Perhaps the Space Shuttle and RAF Nimrods don't vibrate as much as Honda cars, though that seems unlikely! I think it's really down to the conditions in which things are done.

As one of the other posters (almost) said, amateur soldering is probably better than crimping with non-professional crimping tools, on the other hand skilled soldering with top quality materials and environment, proper cable sizes and support, and detailed quality control inspection is likely to be better than the best crimping. Honda cars have to deal with the world of unskilled labour, time pressures and garage environments, where professional crimping tools are available and those particular sort of skills not. MoD & NASA can afford the best (they may have changed specs in recent years for all I know). So in our real world of boats and DIY I would say in order from least to most preferred:
- Crimping with cheap parts and tools
- Reasonable amateur soldering
- Crimping with quality parts and tools
- Professional quality soldering and cabling.
Decide which skills/kit you've got, or can get to your boat, and do the best you can (be bothered with!).

On the other hand it's amazing how well ye olde 'chocolate bar' type connectors can last if your support the cable and joint properly! (Other wise they're appalling source of unreliability and potential fires.)

Happy wiring!