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Old 05-15-2019, 11:37 AM
Yask is offline
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Connections (and quick disconnect) for low-voltage LED lights' wires


I have some solar-powered, outdoor string lights (about ten to fifteen feet in length) that are in need of repair.


Can I just strip wire ends, twist the bare wires together, and secure with some electrical tape? Or do I need to solder them? I'm not good at all with soldering, but I do have an iron and some solder --- would a 'cold solder' (I think that's what a bad solder joint is called) be better than twisting them together?


Second, some of the breaks are at points of stress. I'd really like to add a quick connect/quick disconnect to those points. But when I search "quick connect" I get wire caps and the like, not things meant to be connected/disconnected with ease. I assume such a thing exists, but don't know the right search term.

Third, I have found some things that might work, or I can figure out something to cobble together. But that means going from tiny, thin wires to large-capacity (gauge) wires and clips back to smaller wires. Is that a problem? I can see there being an issue with going from large to small and back, but small to large and back? Or will the signal degrade such that the low-voltage LEDs won't work?

And lastly, does the outdoors use affect things? Do I need to keep all the wires/connectors covered or am I okay just having the exposed parts far enough away so that they won't touch/be in the same water?
  #2  
Old 05-15-2019, 03:44 PM
Tim@T-Bonham.net is offline
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Better, easier than soldering is just a crimped connector. If they're outside, use an insulated, weatherproof crimp connector. Easily available at hardware stores or auto supply places. And the connectors made for automotive use might be good ones to consider if you want to use a connector.
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Old 05-15-2019, 03:49 PM
gotpasswords is offline
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Twisting and taping is better than cold solder joints. At their worst, cold joints are held together with the solder flux acting like glue, and any electrical conductivity is purely by accident.

Are you looking for breakaway connections that will self release when stressed, or just something easily disconnected and reconnected? Any kind of connector will be a liability outside, especially with your LEDs’ low voltage and low current use. It won’t take much corrosion to result in enough added resistance that the lights don’t work.
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Old 05-15-2019, 04:24 PM
Yask is offline
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Thanks. These are for an awning of sorts that comes out on occasional weekends and stays set up for several days. Some weekends are bad luck weather-wise and most have dewy mornings. Otherwise things are stored in a basic, unheated/unair-conditioned garage, so the connectors are likely to dry out when the humidity isn't so bad.

The places where I want the connections to be aren't under stress except on setup and takedown. It's a bit awkward to wrap around the legs and they get tangled/snagged quite easily.

What I'd like to do is mount/secure (hooray for duct tape!) the little solar panel to one leg , secure a run of lights up one side, then end with a connector at the top. I'd mount another run of lights along the top with quick connectors on each end. Then a final run down the opposite leg, this run with just the one connector where it joins the top. That way I don't have to attach/detatch the lights every time we use it --- it comes out, I make the connections and I'm done with it (and reverse when it's time to take it down).


To ask dumb/innocent question: how are crimped connectors better than twisting wires together? I understand why a well-soldered connection would be best. My minimal experience with crimping is crushing a small bit of metal around a wire (I believe my wire strippers have a wiggly crimp area in them). That holds them, but I've had some slip out of the crimp. On the other hand, putting two wires parallel to each other and winding the ends around is also weak, but have more surface area in contact. Assuming resistance to tugging on the ends isn't the point of crimping, I guess my question is from understanding electrical basics. Why would crimping be the right way to do this (also assuming I'm making just a handful of connections and not on a job site where crimping a hundred connections takes a fraction of the time as wrapping them)?


Finally, adding "disconnect" to my Amazon searches led me to things like these. Crimping/wrapping aside, these look like they fit the "connectors made for automotive use" that Tim@T-Bonham.net mentioned.
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Old 05-15-2019, 04:46 PM
Tim@T-Bonham.net is offline
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Quote:
Originally Posted by Yask View Post
To ask dumb/innocent question: how are crimped connectors better than twisting wires together? I understand why a well-soldered connection would be best.
For the average person, it's much fster & more accurate to make a working crimped connection than a 'well-soldered' connection. Might be different, if you are skilled at soldering. Most people aren't.

Quote:
Originally Posted by Yask View Post
Finally, adding "disconnect" to my Amazon searches led me to things like these. Crimping/wrapping aside, these look like they fit the "connectors made for automotive use" that Tim@T-Bonham.net mentioned.
I'd consider these instead. quite similar, except that the existing wires are just crimped right onto the connectors. The other ones have pigtail wires, which then have to be connected to the existing wires somehow.
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Old 05-15-2019, 05:09 PM
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Quote:
Originally Posted by Tim@T-Bonham.net View Post
For the average person, it's much fster & more accurate to make a working crimped connection than a 'well-soldered' connection. Might be different, if you are skilled at soldering. Most people aren't.
From what I understand of soldering (it makes a connection at the molecular level), that's clearly preferred. That said, I'm wondering about the difference between crimping and winding. Crimping would be much more direct, simple and faster, so I see it being the standard in any sort of environment when you don't want to get bogged down in twisting pairs together. But from my one-off point of view, my "I have the extra time on my hands" view, wrapping wires around each other has more of a connection surface-wise.

So, either crimping is favored for some electrical reason (hence the question), because it's simpler and easier and with a good crimp "more surface area" is a silly concept and therefore the time to wrap the wires is wasted, or because of some other reason I don't have enough experince or imagination to ask.



Quote:
I'd consider these instead. quite similar, except that the existing wires are just crimped right onto the connectors. The other ones have pigtail wires, which then have to be connected to the existing wires somehow.
Those look great, thanks!
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Old 05-15-2019, 05:11 PM
jnglmassiv is offline
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I would solder this sort of thing every time.

One thing to watch out for is coated wire. It's quite common for the strands of wire in the cable to have a coating which makes soldering difficult and could make a twisted wire connection marginal or worse.
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Old 05-16-2019, 05:50 AM
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I hate crimp connectors.

I always solder and heat shrink. The investment in tools & supplies isn't that great, and they will last many years. And a competent electrical technician or EE can teach you how to do it in less than 20 minutes.
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Old 05-16-2019, 07:40 AM
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Quote:
Originally Posted by Yask View Post

So, either crimping is favored for some electrical reason (hence the question), because it's simpler and easier and with a good crimp "more surface area" is a silly concept and therefore the time to wrap the wires is wasted, or because of some other reason I don't have enough experince or imagination to ask.
Crimping actually creates more contact area, because it involves enough force to deform the metal, causing the wires (or wire and terminal) to dig into each other. Also, when the metal deforms during crimping, they rub against each other and create clean, unoxidized surfaces that make good contact. (This is also why most connectors are designed to make the terminals to rub against each other when you insert the connector, rather than just touching each other.) Crimping is reliable enough for industrial and aerospace use.

When you twist wires together, the wires are barely touching each other. Even if it looks like a lot of contact area, the actual, functional contact area is microscopic. And much of that contact are will be oxidized or contaminated.
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Old 05-16-2019, 07:47 AM
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P. S. For splicing individual wires, the easiest and most reliable way is to use heat shrink solder sleeves. Just insert the wires and heat with a heat gun till the solder melts. (You do need a good heat gun for this.)

Example : https://www.alliedelec.com/product/t...hoCbFYQAvD_BwE
  #11  
Old 05-16-2019, 09:32 AM
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Quote:
Originally Posted by scr4 View Post
Crimping actually creates more contact area, because it involves enough force to deform the metal, causing the wires (or wire and terminal) to dig into each other. Also, when the metal deforms during crimping, they rub against each other and create clean, unoxidized surfaces that make good contact. (This is also why most connectors are designed to make the terminals to rub against each other when you insert the connector, rather than just touching each other.) Crimping is reliable enough for industrial and aerospace use.
I don't disagree with this. After all, Air Force aircraft contain hundreds of circular ("Amphenol") connectors with pins & sockets that are crimped to wires. And the crimps are very reliable for the following reasons:

1) Careful attention is paid to ensure the pin or socket is used with the correct gauge wire.

2) The correct crimp tool, and appropriate die, is used to make the crimp. Here at work we have a crimp tool kit for making these crimps, and the kit was $2500.

3) The operator is trained and certified to do the crimping.

This is a far cry from the butt splices you buy at the hardware store. They're junk. And most people use the "crimp" jaws on their wire stripper to do it, which does a very poor job of crimping.

As mentioned, soldering and heat-shrinking is pretty simple, and is an order of magnitude more reliable than a standard butt splice crimp. IMO it's a very worthwhile investment if you're a homeowner.
  #12  
Old 05-18-2019, 04:40 PM
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Solar powered lights are DC. LEDs are polarity sensitive. At least the last set I repaired was. Just twisting wires without knowing that becomes a hit or miss deal. Look for tiny print or marks on one of the strands. For long term usage I'd solder just to eliminate the corrosion of the joint. My solar lights rarely last through a second season so I don't really worry much about that. Battery failure is most common and even replacement batteries aren't that effective.
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