Corrosion in FF wires

Was double checking the electrical rigging for my fish finder a couple months ago and discovered that a heat shrink butt splice had failed to create a water tight seal, and introduced water had caused corrosion in the wire contained in the power cable that came with my fish finder. I removed a couple inches of the wire and the internal copper strands seemed to still be affected by corrosion... Took it out looking for squid and the power intermittently failed; playing with it suggested that the issue was coming from the area around where the failed butt splice had been.

I don't know much about corrosion, but what I do know suggests that it can spread pretty easily. I'm looking for input on how far up the factory power cable I should cut in an attempt to 'head off' the corrosion. Also, if anyone has any tips for preventing this in the future, I'd appreciate hearing them. Right now my plan is to use another heat shrink butt splice, and then cover that with another piece of heat shrink tubing.... and then maybe coat it with vaseline?

Image key:
Red circle -- failed heat shrink butt splice
Yellow arrow -- Runs along the corroded wire contained in factory power cable

If it helps, it's a Lowrance Elite Ti7 power cable. Heeding advice from the forum, I've already been applying dielectric grease to the connector that plugs into the head unit.

The corrosion probably doesn't go too far up the cable, but I do suggest cutting back until you see clean copper.  Use you butt splice and then buy some "liquid tape" at the hardware store and apply that over the connection/loose ends of the butt connector.   It's essentially liquid electrical tape that will help create a watertight seal.  Either that or coat the butt splice with Gutter Sealant.  It's pretty hardy stuff.  Also found at the hardware store.   I also suggest putting some dialectic grease on your terminal connectors to help seal out water intrusion. 

Slather the new splice with GS121 or Marine Goop. Then slide the heat shrink over it and let the shrinkage squeeze out the excess. It won't happen again.

Show us the corrosion and then we can guess how far it goes.
Are we talking solid green or just a bit of tarnish?
My experience is that the corrosion will go much farther than you like.


To stop the same thing on your next evolution you need two things.
Water proof butt connectors and then marine heat shrink to tie it all together.
The marine heat shrink has a water proof adhesive that melts to seal the connection.
Both are available at Harbor Freight.

I haven't used butt splices in a long time because it stopped making sense to use Ancor marine splices, then liquid electrical tape and finally double-wall adhesive-lined marine heat shrink tubing - and still keep my fingers crossed that it's watertight...  Now I just twist the wire ends together (similar to how it's done in this video:



Then cover it with a section of marine-grade double-wall heat shrink tubing extending at least 3/4 inch past each end of the splice and Fanny's your Auntie.  You can slap a thin layer of liquid electrical tape or Goop on the exposed wire before sealing it with shrink tubing if you want, but adhesive-lined tubing is plenty waterproof without it.

These twisted splices are significantly stronger and much more reliable than any crimped or heat-shrink splices when joining multi-strand wires, and especially more reliable when you need to join wires of different gauges.

I solder the connection, squirt a bunch of dielectric grease on it, then heat shrink it until the grease squirts out.

If you plug in a multimeter to the red plug you can get an idea when you should stop cutting the power cord when the voltage reads the same as the battery. You can also measure the Ohms on a multimeter for continuity on the positive for the same effect.

The power cable is also like 30$ on amazon if you need to replace it. I run the same fish finder and keep a spare in my shop.
https://www.amazon.com/Lowrance-000-14041-001-Boating-Electrical-Equipment/dp/B0719497SY

PSA:

This is why you buy fish finders that have two plugs, one for the power one for the transducer. There are fish finders that share a plug for both the transducer and power, which you'll be out the entire cost of a transducer for something as minor as this.

Thanks all for the approaches for affecting a fix and general advice RE prophylactic measures.

Following BentRod’s advice, I’ll cut until I see good copper… And then per workhard’s suggestion, test the connection with a multimeter before joining them permanently. 

For the permanent splice, I’ll probably use Tinker’s method for joining the two wires, and then seal it with a combo of liquid tape and marine grade double-wall heat shrink tubing. That’s a pretty cool joining method…. reminds me of an FG knot.

In terms of prophylaxis…
   (1) Coat terminal ends w/ liquid tape, then with dielectric grease
   (2) Buy spare power cord

Thanks again for the wealth of information. I never messed around with electronics on my kayaks back east; since I’ve been using them out here they’ve pretty much been an afterthought… And I’ve just been lucky, or not used them long enough, to not pay for not being thorough.

For some strange reason, I had never heard of "marine" shrink tubing with an adhesive lining inside. And I have been using shrink tubing going back to the days they invented it. THANKS to the posters who brought this great improvement to my attention. Already a great start to a New Year. Found a great assortment kit of red and black adhesive tubing on Amazon for $9.

This spring after breakup, I'll be resealing all my wiring harness connections on the trailers for my ATV, boat, and two utility trailers as well as redo my boat and kayak electronics wiring connections. My bro and a friend, all old geezers like me, had never heard of it either. And no, we don't live in caves here in AK. Nor were we in a coma. LOL

Only 14 Below Zero this morning. By next Tuesday through Friday it will be hitting 32°F....that's ABOVE zero. Anyone want to start a GoFundMe for my natural gas heating bill? 

Cheers to a new year!

KK, I was literally just complaining about cold outside working and it is in the low 40s. BBRRRR

GoFundMe indeed Klondike Kid. I track temperatures for future fishing locations (torturing myself) and here in Cheyenne we will briefly drop to -4 as a low tonight while Riverdale North Dakota (Ft Peck Lake) has seen a string of lows in the lower -20s.  Kalispel Mt (Flathead Lake) has seen a sting of negative temps ranging from -7 to -12.    I love Alaska's summer temperatures but winter?  Not so much........  In the meantime, Corpus Christi high temps have been running from 57 to 81 (nice temps for the intercoastal waterway).   

For connections that can’t be sealed in the ways described by everyone else, this is a really good option. Terminal connections, for example.

I worked 20 years rigging and fixing boats.  One problem that I've seen  is on a center console boat I needed to extent the battery cables to under the console .  I would make the extension cable with the same size connector and bolt together with 1/4-20 bolt. I would seal it up with marine shrink tubing with internal glue. After several years a few boats came back with starting problem.  In all cases the positive wire on the battery side was expanding (corroding) right at the junction point.  The connection was under the floor but not laying in the bilge. The fix even on new boats was to remove and replace the entire cable from battery to inside motor!  These connections were water tight and imo there was something else that was going on.
  The air force did studies and the best connection is the cold crimp butt joint with marine shrink tubing, I have made many (hundreds) connections like this on smaller wires and had no problems, it is important that the correct size connector is used with the correct size wire.  And yes the marine shrink tubing with internal glue makes all the difference!

The Air Force doesn't operate in (or particularly near) saltwater...

The Air Force doesn't operate in (or particularly near) saltwater...

The study was crimp vs solder with respect to vibration, sorry if I didn't make that clear.

Amazon has waterproof heat-shrink connectors with a solder ring in the middle, overlap both wires inside the tubing and use a heat gun to melt solder and shrink the tubing, I've had no problems with those, come in a box of several sizes for about $11 or so.

https://www.amazon.com/Connector-Qibaok-Waterproof-Electrical-Automotive/dp/B083DXC9TP/ref=sr_1_6?crid=L4IEKJL30KIG&keywords=heat+shrink+solder+connection&qid=1642886249&sprefix=heat+shrink+solder+connection%2Caps%2C445&sr=8-6