Electrical soldering/connections basics.

[V8srfun]

I wanted to try and contribute something to the forum so here it goes

This is a basic soldering and wire connections walk thru

1. Disconnect your battery/batteries
This is for your safety and so you do not damage any thing. After all I don't think any of us are certified in 12 volt wielding

2. Inspect the wire you want to repair
If there is any corrosion or the wire does not look like fresh shiny copper cut it back until it does. If you do not start with clean corrosion free wire you are just asking for trouble and future headaches.

3. Be prepared
Have all your tools and what ever you need ready soldering is a meticulous task so there is no need to make it worse

4. Repair time
Now that we are ready now to perform the repair slip your heat shrink down one of the wires once you solder them you can't put it on. Now you can strip your wire casing back and connect the 2 pieces together. There are a couple ways you can put them together you can twist them like a bread tie, make both ends into j hooks and then squeeze them down , or mesh the wire together which I never have luck with because the strands usually bunch up and make a mess. What ever way you choose is irrelevant as long as the solder joint is good. Now get out your soldering iron and heat the wire from underneath. Do not heat the wire from the top. Now take your solder and push down on the wire lightly. What you are doing here is helping the heat transfer thru the iron to the wire. When the wire gets hot enough the solder will begin to melt. The solder should wick through the wire strands and encase all the exposed copper. When you have heated the wire and solder properly you can not over apply the solder as any excess will drop right off so do not be scared. Do not melt the solder on the iron to speed the process this will produce what is called a cold solder and will have high resistance be weak and essentially will be worthless.

Now that you have solders the wire let it cool this should not take long and inspect your repair. The solder should cover all of the exposed wire and be evenly dispersed. Note if you have your wire heated properly like instructed above you can apply the solder all in one spot and it will disperse itself throughout the wire. With that said if you are having trouble with the solder flowing chances are that you don't have enough heat in the wire. So now that you have a good looking solder joint with enough solder in it to properly conduct electricity you need to check the strength of the joint. Always pull test your joint and be fairly aggressive with this because it is easier to fix it now than later.

After inspection has passed you need to seal your solder joint the best way to do this is with heat shrink. There are 2 types of heat shrink. One is just that heat shrink and the other is self sealing heat shrink that has glue inside. Both of these are sufficient but If you do not have self sealing you need to apply a small amount of dielectric tune up grease to the solder to protect it before using the heat shrink. Then heat up the heat shrink until it has shrunk down and tightly wrapped around the wire.

Now I have a couple pics to show what all we have gone over


These two solder joints are what you want to look for you can see how the solder looks like it melted into the wire and has encased all of the exposed copper

i have a couple more posts to come after this one the way this forum posts pics it would be to hard to do this all in one post

 

[V8srfun]

This is a cold solder you can see how it looks like it is just sitting on the wire and has not been absorbed by the wire the 2 main causes of this not enough heat in the wire and or dirty/corroded wire. The pic with the wire going horozontally across your screen is not supposed to be in this post so just ignore it for now. You want to reference the second pic.

 

[V8srfun]

This solder joint form the other side looks perfect but upon closer inspection you can see that there was not enough solder melted into the wire. This is whi you need to closely inspect your work because this looks good from the top but there could be a potential for high resistance in this joint because of the lack of solder

 

[V8srfun]

This repair has been covered with self sealing heat shrink and it was properly heated until the glue melted out on both ends producing a water tight seal. But If you look at the one end of the heat shrink it barely overlaps the end of the solder joint and can potentially become a weak spot in the seal. Always use enough heat shrink it is not worth skimping on it then having to deal with corrosion later down the road.

 

[V8srfun]

It is hard to see in this pic but you just need to apply a light/thin coat of dielectric tune up grease to the joint if you do not have self sealing heat shrink this is to promote a good seal and fight corrosion

 

[V8srfun]

Here is what it looks like when you have enough heat shrink extending out past the solder joint. Notice this is not self sealing so there is a light amount of dielectric grease under the tubing to act as the sealant

 

[V8srfun]

Here there are there connectors and what I am showing them for is to help with identification of what ones have built in heat shrink and what ones do not
The top but splice is the only one here with built in heat shrink. So after making your connection please use the heat shrink (I can not even begin to tell you how many connectors I have seen with built in heat shrink and the person never took the time to heat it)

The bottom two are not heat shrinkable the easiest way to tell is that heat shrink is flexible and the others are hard plastic

 

[V8srfun]

This is a proper but splice note how rhe wire is not over stripped and you can not see excess copper then the heat shrink was thoroughly heated until the glue melted out. But not melted to the point of being burned.

 

[V8srfun]

Here we have two ring terminals both are good but if you have a choice always go for one that has the end sealed like the copper one. They are easier to seal and much less likely to have corrosion problems

 

[V8srfun]

And for my last pic make shure you use the right kind of crimp for the job
You will see where the crimper says bare or insulated. This refers to the connector do not use the bare crimp for a but splice with built in heat shrink you will pierce the heat shrink and make it useless

I hope this helps thanks for reading

 

[Guyfang]

The only thing wrong with a soldered wire is that if you ever have the wire get HOT, like a short circuit, or an over loaded circuit, it can melt the solder and come apart. That's the reason you don't solder wires in a house installation. An overloaded circuit makes heat. You have all seen wires on trucks and generators that have a burnt up wire harness. Well, if it's hot enough to smoke a harness, it's hot enough to melt a solder joint. A butt connector is a much better way to fix a broken/cut wire. The butt connector pictures illustrated here are a perfect butt connector joint. And the advice on using the right crimping tool is 100% right. I saw a generator wire harness burn up because one of my people used a crimper tool for an uninsulated ring terminal, on an insulated terminal. The crimper tool punched a hole in the insolation on the terminal, causing it to fall off, and it shorted out during a load test.

 

[gottaluvit]

I just made slave cables with 2/0 wire and crimped the ring ends on first and then soldered. I feel "keeping" the good connection will prevent the heat in the first place. Of course with that heavy of a wire I had to use a torch to get it hot enough to make the solder sweat in. I also always scrape both the wire and the terminals to very shiny metal before I start.

 

[V8srfun]

Thanks for the input I will not argue your point because you are right but I will add that if the solder melts the connection may break and prevent further damage.

The truth is I always use connectors but some people live in the past and think solder is the only way.

 

[Guyfang]

There is a time and place for solder. I still have my soldering iron that I bought 30+ years ago. It still get used a bunch. When a circuit is low volt/amperage, then I don't think twice. Or when I have problems with a circuit card/board. Re-solder every connection, and often it is as good as new.

 

[V8srfun]

Like you said in your previous post solder is not particularly the proper repair for household voltage but this is a automotive forum. In the low voltage stuff we will be working on there is nothing wrong with using solder as a repair. I would recommend that people use what they are comfortable with or what they have readily available. If I run out of solder there is no shame in using a butt connector to finish the job or vice versa. But the reality is this thread was intended to inform people that did not know how to solder and not to debate the proper time and place to use it.

 

[The HUlk]

Generally speaking, if any wiring or connection gets hot enough to melt solder that would be indicative of incorrect conductor guage or contact area size for the required ampacity as well as no circuit breaker protection being used. Both are bad ideas for the most part.

 

[gottaluvit]

I would "think" the insulation would catch fire before a good solder joint could melt. Just my 1 3/4 cents.

 

[Suprman]

I like the crimp then solder and heat shrink over for the best possible long lasting connection. I have seen alot of military-done crimp connections corrode over years of service and go bad. Something solder along with the original crimp would have prevented.

 

[daytonatrbo]

One thing I would add to this, or maybe I shouldn't since it may confuse a first timer... but:

Always tin your soldering iron. Basically, clean the tip of your iron, then apply a small amount of solder to the tip. Not enough to make a blob, just enough to smoothly cover the tip.

This will allow MUCH better heat transfer into the wire. You will be able to heat the wire more quickly and finish more quickly, which means less damage to the nearby insulation.


Sometimes I find myself soldering a wire that is maybe just too big for the effective heat range of one of my smaller irons. In that case I will use more "tin" on the tip to get more heat into the wire. But you really have to inspect the work afterwards to make sure it didn't come out cold. It's also something that becomes easier to judge with experience.

 

[Hard Head]

I worked in an electronics shop for 2 years. I probably desoldered (which can be harder technique to learn than soldering) and soldered tens of thousands of circuit board connections. Multi layer boards require very good soldering equipment and solder. Clean your soldering iron and desoldering tip frequently and tin them like mentioned in the preceding post! Another very good point is conductor size. Many high temp wire insulators such as those use by the military might not show over heating like you are use to seeing with standard automotive wire. If for some reason I touch a conductor before crimping, I clean it before I crimp it. I see a lot of people twisting wire with their fingers before crimping (that may lead to corrosion). Tin conductors before soldering. Use additional flux especially on large areas. Flux (Rosin type in our case) melts of at a lower temp than solder insuring that it does it's job before the solder takes hold thus helping to make a proper joint or bond. Buy a very good temperature adjustable soldering station. They are not expensive and are well worth the money. Get rid of that 9.99 soldering iron!