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Waterproof DC Power Cable Set gauge? (Teardrop Trailer wirin
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Waterproof DC Power Cable Set gauge? (Teardrop Trailer wirin

by kyleoliveira on Fri Aug 09, 2019 8:23 pm

I've bought '50s-era teardrop trailer recently and while it's in pretty good shape, it has a small drawback with respect to the interior lighting. There are two 12v dome lights using T57 bulbs (one in the cabin, one for the galley) and they're wired up to run off of a standard car battery via a long cable ending in alligator clips. This is kinda... quaint and I'd like to rewire it so I can disconnect most of the cable and swap it for a battery pack (specifically a Jackery Explorer 160).

What I'm intending to do is cut the cable and patch in a DC Power Cable Set with the female side attached to the trailer wiring. I'll connect the male side to the remaining cabling. The goal is to be able to reattach the long cable in the event that I want to use a car battery, or (usually) connect to the battery pack. To connect to the battery pack, I've got a 12v USB to 2.1mm DC Booster Cable.

Additionally, I'm swapping out the T57 bulbs for LEDs that'll fit the same socket. So far these should be the only things on this circuit.

So,
* Is this a bad plan? (If so, help! :D )
* What gauge wire would the Waterproof DC Power Cable Set be? Looks like maybe 22?
* The existing wiring is quite a bit thicker than that cable set... Should I be concerned or take any particular precautions?

kyleoliveira
 
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Re: Waterproof DC Power Cable Set gauge? (Teardrop Trailer w

by adafruit_support_mike on Sat Aug 10, 2019 1:07 am

That sounds like a good plan.

kyleoliveira wrote:* What gauge wire would the Waterproof DC Power Cable Set be? Looks like maybe 22?

Yep, it's 22-gauge, which should be good for up to about 3A.

kyleoliveira wrote:* The existing wiring is quite a bit thicker than that cable set... Should I be concerned or take any particular precautions?

There's no reason for concern. Incandescent lamps use a lot more current than LEDs, and older wiring is usually heavier than new stuff.

It would be worth your time to check the insulation on the existing wire and see if it shows any signs of brittleness or cracking. If so, it would be a good idea to replace it, or disconnect it and run new wire in parallel with it. You can get coils of stranded wire cheap in any auto parts store.

If the old wiring is good, the major challenge is connecting a smaller line to a larger one.

Properly crimped connections are almost always stronger and more reliable than soldered connections, and you can also find crimp sleeves in an auto parts store. Find a size large enough to fit the large wire in from one side and the small wire in from the other (overlapping each other), and crimp so the deformed part of the sleeve bears down on the small wire.

The small wire will probably be much smaller than the end of the crimp sleeve, so it's a good idea to run some hot melt or epoxy into that side of the sleeve to fill the gap. It provides some strain relief for the wire and prevents gunk from getting into the connector.

When in doubt, the NASA Workmanship Standards are always a good source of heavily-tested ideas:

https://workmanship.nasa.gov/lib/insp/2 ... meset.html

adafruit_support_mike
 
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Re: Waterproof DC Power Cable Set gauge? (Teardrop Trailer w

by kyleoliveira on Sat Aug 10, 2019 2:33 pm

Excellent! Thank you Mike!

I've just barely done any electrical (obviously), but I had been planning on a lineman splice and some solder, then cover with heatshrink tubing. The crimp sleeve would probably be a bit easier to implement, though.

kyleoliveira
 
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Re: Waterproof DC Power Cable Set gauge? (Teardrop Trailer w

by adafruit_support_mike on Sat Aug 10, 2019 6:40 pm

The lineman's splice is really hard to do when the wires are different sizes.

If you want a low-profile soldered connection, it's usually easier to do a lash splice: lay the two wires next to each other, wrap 30-gauge wire around them for the mechanical connection, then solder the whole thing and cover it with heat shrink.

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Re: Waterproof DC Power Cable Set gauge? (Teardrop Trailer w

by kyleoliveira on Sun Aug 11, 2019 12:32 pm

Ah, interesting... I might give that a shot then. I'll let y'all know how it goes in the end ^_-

kyleoliveira
 
Posts: 3
Joined: Fri Aug 09, 2019 8:01 pm

Please be positive and constructive with your questions and comments.