To Grease Or Not To Grease?

[Cadence]

Originally Posted by Bycrick

A crimped connection is a SYSTEM. The terminal has to be made of of the proper materials, of the correct construction and of a consistent size. Buying the best quality terminals isn’t expensive if you buy them 100 at a time. My last stock was about $0.25/ea for heat-shrink yellow terminals. Blue and red were about 30% less. 2/0 heavy-duty terminals were just over $1/ea and the typical starter-terminals that you commonly see we’re about $0.70/ea.

The tool has to compress the terminal a consistent amount (not too much, not too little) and in the right shape. A high-quality tool will do this consistently. A poor quality tool won’t. Maybe I don’t need a $500 certified AMP crimper, but $100 for a good crimper isn’t a big expense for somebody who can afford a 40’ boat.

If the connection is not completely sealed, moisture will eventually get inside and start corrosion. Once that happens, it makes little difference whether you’ve used tinned or untinned wire or whether you’ve crimped or soldered or both, because the wire itself will eventually fail.

Solder is a poor electrical conductor, only about 10-12% the conductivity of copper. On low-current circuits, it doesn’t matter. Even if solder was a good conductor, when you try to use it to make a connection in 2/0 boat cable composed of over a thousand small wires, you have no way of knowing how well it’s wetted out and adhered to the individual wires.

I'd need to agree solder is the way to go with heat shrink for low current control wires. No way once into the /0 wire.

[redneckrob]

Originally Posted by Pauls

I agree with Wotname's post. To amplify a little on the difference between a really good crimp and the not so good, a really good crimp applies enough pressure all the way around the terminal and wire to pretty much swage them into a single mass. If you cross section the joint there will be no voids, no gaps. IE no place inside the joint for corrosion to start.

Your typical auto parts store crimper smashes the terminal onto the wire and it will work electrically but there are gaps and voids galore.

The middle of the road stuff being linked to is somewhere between these two.

The nice thing about solder is that it creates a hermetic joint, a 100% filled joint, and it does it easily, repeatably and with a simple iron or torch.

I was actually talking the hydraulic crimpers with die that you use on 4 AWG or bigger wires. If the die is the right shape, it's not clear to me what has to be calibrated. You just operate what is effectively a hydraulic jack on its side until the die meets, at which point the pressure no longer matters because it can't go any further. I am getting the distinct impression I'm missing something on how real mission critical crimping is done.

[Bycrick]

WRT the "filling the voids" myth. If the crimp connection is properly made, ie gas-tight, there are no voids to fill. If you have dielectric grease in any voids, any moisture will wick up the wire and corrode under the insulation. If you try to fill the terminal with solder, it will wick some distance up the wire and create an unsupported hard spot. And if moisture gets in, it will simply go further up the wire before it corrodes. If the wire isn’t perfectly clean before you solder, then the solder doesn’t bond to the wire, leaving a path for moisture. If you fill the joint with flux, then any trapped flux creates its own voids. In either case, there shouldn’t be any voids to fill. If you get moisture into the connection, it will corrode the wire whether or not you’ve filled any voids caused by poor crimping.

WRT "calibrated" crimp tools. The HF hydraulic crimpers will only go "so tight and no more." That’s repeatable. But, for example, SAE gauge wire has a slightly smaller conductor than the same sized AWG. So an identical lug will not be as tightly crimped on an SAE wire when compared to an AWG wire unless you can adjust the jaw closure. On insulated lugs, where you apply crimp pressure through the insulation, the hardness of the plastic will affect the amount of crimp pressure applied to the terminal shank and wire. For battery type lugs, even if the interior diameter matches the wire, various different lugs (different quality or manufacturers) can have different wall thickness therefore requiring a different die opening.

FTZ sells two different terminals, a starter terminal and a heavy-duty terminal with a longer and thicker body. There are two different crimp settings. With auto parts lugs, you won’t know what the variations are.

[Wotname]

Originally Posted by redneckrob

I was actually talking the hydraulic crimpers with die that you use on 4 AWG or bigger wires. If the die is the right shape, it's not clear to me what has to be calibrated. You just operate what is effectively a hydraulic jack on its side until the die meets, at which point the pressure no longer matters because it can't go any further. I am getting the distinct impression I'm missing something on how real mission critical crimping is done.

What Brick said plus...
Are the dies exactly the right size, have they worn or ....

Real mission critical crimping specifics the using crimps and tooling made by the same manufacturer and a specific wire size - not just any crimp and an approximate wire size. Mostly mission critical crimping is not performed on recreational boat or even on a mega yacht!

Certified crimps to a NATA standard usually specifies a go/nogo outside dimension, a maximum resistance in the order of milliohms (which requires a certified conductance test meter) and a wire pull out test with certified weights.

I recall trying to certify a very nice Snap-On hand held hydraulic crimper - it made great crimps and I would be happy to have them on my boat but only some of the jaw sets meet most requirements and some of the jaw sets didn't meet any standard. They produced very repeatable results. Would they be any good on my boat - yes they would have been great but so would have been much cheaper ones.

One man's mission critical standard is another man's sloppy work

[bharney]

I've been soldering connections on my boat similar to Capt Coullion's method for decades and have never had one fail.