Of Crimps and Fires: A Cautionary Tale

[dlochner]

Ryan and Sophie a is a YouTube channel I've been following. This week they published an article that should remind us of the importance of good craftsmanship when working with electricity. They were close to losing their boat due to bad crimping on the primary wires.

Here's a link to the article. Well worth the read. And their videos are a hoot. Sophie is a good story teller and funny. One of my favorites.

How bad crimping almost burned down our boat. - Ryan & Sophie Sailing

After two weeks in Sweden, we came back to Polar Seal on Monday to tackle some serious boat preps ahead of our Atlantic crossing this coming December. One aspect of these preparations was to replace our Sunbeam deck solar panels, that had been performing poorly since we installed them last year...

ryanandsophie.com

 

[Jim26m]

Interesting read. I'll be interested to see the commentary on those connections.

For small wiring, I'm a solder and heat shrink guy. Connections that size are a bit more difficult to accomplish in that manner, so I get the desire to crimp them. Just seems like using that method in a salt laden atmosphere, and subjecting the connections to very high current continuously, is risky. I notice that a lot of boats are moving to all-electric appliances, and wondered how the low voltage side would hold up under continuous high load.

Thanks for posting that.

 

[IStream]

Both the "good" crimp and the "bad" crimp they showed look over-crimped to me.

 

[markwbird]

I am curious what was "bad" about it. What does a good crimp do that a bad crimp doesn't do and why does it heat up?

 

[dlochner]

I am curious what was "bad" about it. What does a good crimp do that a bad crimp doesn't do and why does it heat up?

If the crimp is not tight enough the electrical connection is not as solid. When high currents are passed through the crimp, the resistance causes the terminal to heat up. On Polar Seal the resistance was high enough to cause the tape to start melting.

A second issue is sealing the crimp to prevent moisture from entering the crimp and the cable. The moisture, especially salt water moisture causes corrosion which increases resistance, adds heat, and melts insulating material and electrical tape.

The cable is also not tinned wire. Bare copper strands are more prone to corrosion.

See this article for more information: Making Your Own Battery Cables

 

[jssailem]

What @dlochner said.

 

[Garbonzo]

Both the "good" crimp and the "bad" crimp they showed look over-crimped to me.

What is the meaning of overcrimped? And how do you prevent it. The professional one did look pretty squished to me,

 

[Garbonzo]

If the crimp is not tight enough the electrical connection is not as solid. When high currents are passed through the crimp, the resistance causes the terminal to heat up. On Polar Seal the resistance was high enough to cause the tape to start melting.

A second issue is sealing the crimp to prevent moisture from entering the crimp and the cable. The moisture, especially salt water moisture causes corrosion which increases resistance, adds heat, and melts insulating material and electrical tape.

The cable is also not tinned wire. Bare copper strands are more prone to corrosion.

See this article for more information: Making Your Own Battery Cables

So one says overcrimped and one says undercrimped. Which is it. I can understand undercrimped, but what is overcrimped?

 

[IStream]

Take a look at the "wings" on either side of the lug after crimping. That's lug material that flowed between the two halves of the crimping die because the opening in the die was too small for the size and thickness of the lug. It weakens the lug and thins the cross sectional area of the lug where it meets the wire, reducing current capacity.

 

[Maine Sail]

Both the "good" crimp and the "bad" crimp they showed look over-crimped to me.

Yes both examples are poor crimp executions, but they appear to have many more issues lurking in that wiring then they are not picking up on. There is as much spaghetti in there as a meal at Mama Mia's....