Crimping two wires together on the same crimp-connector it's criminal?

Thread Starter

gimpo

Joined Jan 27, 2016
123
I need to "steal" +12 Volt from a motorcycle power connector in order to power my custom circuit. The smarter solution seems to be crimping my two wires (+12V and GND) together with the pre-existing ones and plug them into the same housing receptacle.
I've read that two wires should be never crimped together; on the other hand I saw many people doing that. Anybody has experience about it?

(Before you ask: yes, I would love to make a more reliable soldered-joint, but then I don't know how to make an "Y-joint" insulated and waterproof - i.e. there are not Y-shaped heat shrinks.)
 

Lestraveled

Joined May 19, 2014
1,946
I see no problem with putting two wires into a crimp connector if the sum of their diameters do not exceed the crimp connector. In other words, if they fit, they will crimp.:D
 

tcmtech

Joined Nov 4, 2013
2,868
WHo ever told you that two or more wire can't be crimped together doesn't have their facts right.

Its a common practice everywhere.

As for the heat shrinking problem just fill it with silicone before shrinking it and it will seal around two or more wires just fine.
 

#12

Joined Nov 30, 2010
18,167
Stuff in as many as will fit, crimp, and solder.
Solder cures many evils!
The only problem I ever had in 50 years of this was a manufacturer of $6000 lasers that crimped 9 wires in a ground lug and some assembly line monkey didn't come down hard enough on the crimper. Multiple intermittent grounds. The kind of circuit you can't, "simulate".:D
 

Thread Starter

gimpo

Joined Jan 27, 2016
123
I see no problem with putting two wires into a crimp connector if the sum of their diameters do not exceed the crimp connector. In other words, if they fit, they will crimp.:D
I think so too, I would use a slightly larger crimp-connector that can accommodate my two wires with no problem. At the same time I've read a lot of opinion against doing that: it is a not orthodox way to crimp a contacts as reported in "esoteric" industrial manuals and guides.
I hope the I will not go to the hell 'cause of it... :D

Just an additional question: should I slightly tin the wires before crimping in your opinion? Should I twist the two wires together or not? (Ok, these are two questions, not one.)
 

Thread Starter

gimpo

Joined Jan 27, 2016
123
As for the heat shrinking problem just fill it with silicone before shrinking it and it will seal around two or more wires just fine.
Thanks for the answer tcmtech.
To be honest, I did not fully understand the sentence above. Covering the wires with silicone before crimping them will not decrease conductivity?
 

#12

Joined Nov 30, 2010
18,167
should I slightly tin the wires before crimping in your opinion?
No. That will make them resist mushing, then the tension will collapse when you re-heat them. You can twist each wire unto itself, but don't twist them together.
 

Thread Starter

gimpo

Joined Jan 27, 2016
123
No. Crimp, solder, silicone, shrink.
Ah! Ok, now it's clear.
Just a doubt: there is no big space to apply solder on the connector. Should I make the uninsulated part of the wire a little bit longer in order to apply a little amount of solder?
 

#12

Joined Nov 30, 2010
18,167
A tiny bit of copper should be seen at each end of the crimp barrel. That proves the wire is inserted all the way and no insulation is caught in the crimp. This tiny copper length also allows you to see if the solder wicked completely through the barrel.

Amazing the things you learn in 50 years!:D
I completely forgot how many rules you follow for a crimp connector, even though I installed a few dozen this week.
 
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Thread Starter

gimpo

Joined Jan 27, 2016
123
A tiny bit of copper should be seen at each end of the crimp barrel. That proves the wire is inserted all the way and no insulation is caught int the crimp. This tiny copper length also allows you to see if the solder wicked completely through the barrel.
In other words, looking at the picture below, I should apply solder in points A and B and let it flowing inside the "conductor crimp" (or "crimp barrel") to fill it. I'm right?
Selection_021.jpg
 

jpanhalt

Joined Jan 18, 2008
8,331
1) Crimp connectors are used with stranded wire. Depending on the stranding, you have that many individual wires attached. So adding a few more doesn't hurt, given the constraint of total wire diameter.

2) As for solder, there may be specifications that forbid that. In aircraft, for example, when a crimped connection is specified, a soldered and crimped connection may not be. In general and barring such regulations, soldering probably doesn't hurt, but it may not help either to a well-crimped connection.

John
 

#12

Joined Nov 30, 2010
18,167
You can heat the conductor crimp and add solder at "B" then watch for the solder to flow to the "A" point.
Use a tiny dot of solder on the contact point where the iron meets the crimp. When you're done, tap the connector so the solder dot will fly off on to the floor.
 

#12

Joined Nov 30, 2010
18,167
it may not help either to a well-crimped connection.
I've seen so many crappy crimps that I go for the solder. You will NEVER jerk a crimped wire out if it's soldered.
Then again, the solder does cause a lack of flexibility right at the crimp. Two layers of shrink tubing, the outer longer than the inner, provide some amount of resistance to flexing which might eventually cause embrittlement right where the solder stops and the flexible wire starts.
 

Thread Starter

gimpo

Joined Jan 27, 2016
123
You can heat the conductor crimp and add solder at "B" then watch for the solder to flow to the "A" point.
roger
Use a tiny dot of solder on the contact point where the iron meets the crimp. When you're done, tap the connector so the solder dot will fly off on to the floor.
roger roger

(Yes, as you suspect, I'm forced to watch the "Clone Wars" cartoon series with my little son :D )
 

Marcus2012

Joined Feb 22, 2015
382
Dad always taught me solder a crimp for solid core and crimp it for stranded :) But I do have a tendency to solder stranded splices and use adhesive heat shrink so it doesn't flex too much.
 
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