Running with a faulty alternater ... OK?

[Wotname]

Originally Posted by goboatingnow

Using Dielectric Grease on the Power Connections of a Garmin Marine Device
Dielectric grease is commonly used to lubricate and help seal electrical connectors to prevent water intrusion in a marine environment. While the power cables for Garmin marine devices are designed to prevent any water from accessing the power connections, if an extra level of protection is desired, dielectric grease can be used.

Since Dielectric Grease is an insulator, do not apply the compound directly to the metal contacts. Instead, coat the outside of the connector and the connector's O-ring seal, if applicable, with a thin coat of grease. This will ensure a seal that will protect the contacts from the elements without impeding the electrical connection.

Having been a Garmin distributor since it was a start up small avionics outfit (ProNav, owned by Gary B and Min K) I have watched Garmin devolve into a multinational giant and noted the corporate CYA concept take over.

Of course they must warn about 'dielectric grease' as the term is so broad, some unthinking person will use an unsuitable dielectric product and blame / sue Garmin.

However I can assure anyone who can think critically that some dielectric greases (i.e like the ones previously mentioned upthread) are suitable to use Garmin connectors.

Lawyers know law, engineers know detail.

[Dieseldude]

The problem of sealing a connection and maintaining conductivity is one of conflicting objectives. A perfectly sealed connection may have low conductivity. An unsealed connection may have good conductivity for a while, but become resistive eventually due to corrosion caused by water infiltration. Grease directly applied to mating conductors will seldom stop all current. Microscopic bumps on the surfaces will make contact, but there is doubt as to whether contact area will be sufficient. Wotname has some direct experience that shows directly greasing mating surfaces is ok. I don't like to doubt anyone's experience. But I would find it difficult to go against my instinct that says grease is a resistive layer. I would still opt for sealing the outside surfaces and leaving electrical contact surfaces dry. But if I were in his position and saw repeat failures, I would likely try directly greasing mating contacts too. And I have never used DC4 grease, so maybe that is my problem. There is nothing like first hand experimentation. Even a practice that goes against one's basic reasoning, can sometimes prove effective. The slang for such things used to be "black magic". It defies reason, but it works.



As for double wall heat shrink, if carefully applied so that no air pockets are left, and if not allowed to be damaged, why would it not work ? Perhaps problems are encountered due air pockets that become tiny water pockets. Perhaps the heat shrink gets damaged in some cases. I have used it and it has worked for me.


I had been of the reasoning that soldering a crimped terminal would prevent water being drawn in by capillary action. But according to Bowdrie thermal expansion weakens the crimp joint. Perhaps, but how strong must it be ? Of course soldering without crimping will be weak. But crimping and soldering is weak ? Upon cooling, a copper wire and copper terminal will shrink at the same rate. Will the solder not shrink enough and pressure the joint, or will it shrink too much and leave voids or cause tension ? Solder is quite malliable, so will conform quite well to pressure. Will uneven tension or pressure cause the joint to fail ? This seems like a matter for metallurgists and physicists to settle. What would we as marine engineers and electricians know about microscopic behavior of metals ? One known problem with solder is that if it is disturbed while changing from molten to solid, it crystalizes and will be resistive. This is commonly called a "cold solder" joint. So care is required not to disturb it until sufficiently cooled, and never cool it too quickly with water.

[goboatingnow]

Soldering a crimp is bad
Because it wicks up the cable strands and produces a hard point beyond the crimp boundaries. This then fails over time

Secondly a good crimp is has tight and is impervious

Thirdly a crimp is designed in most cases to grasp the sheath and use it as strain relief this is usually impossible if soldered.

Cable Solder joints subject to any vibration need physical strain relief.

[goboatingnow]

Note that all dielectric grease is non conductive so the concerns apply to all such greases.

[Dieseldude]

OK, thanks goboating now for the details on why not to solder a crimped joint. Makes sense. Solder wicking up the wire does form a mechanical discontinuity which can fail with vibrations. I have seen some crimp lugs made to grasp the insulation, and some that lack this feature, That is one reason to use some thick heat shrink over the joint.


And yes, dielectric greases are insulators, so I would still opt to keep it off mating contact surfaces.

[Wotname]

Originally Posted by goboatingnow

Note that all dielectric grease is non conductive so the concerns apply to all such greases.

Yes and no, all dielectric grease is non-conductive but they have different abilities to flow under pressure.

Air is also non-conductive so perhaps we shouldn't let air get between the mating surfaces of terminations.

[David Mathis]

Something has caused the alternator to fail. You're going to sea with a known faulty part. Do you see a problem with this decision? Will it get worse and seize a bearing? Will it start a fire? Rather than ask CF members to make guesses as to the cause of the failure, why don't you just get it fixed or replace it? An alternator is a relatively cheap part to replace.

[Wotname]

Originally Posted by goboatingnow

Soldering a crimp is bad
Because it wicks up the cable strands and produces a hard point beyond the crimp boundaries. This then fails over time

Secondly a good crimp is has tight and is impervious

Thirdly a crimp is designed in most cases to grasp the sheath and use it as strain relief this is usually impossible if soldered.

Cable Solder joints subject to any vibration need physical strain relief.

While I agree that soldering a correctly crimp connection is a no-no, I fail see to understand the logic of saying a good crimp is impervious and yet solder can wick through it. Surely it is one or the other and mostly IME, good crimps aren't impervious although I know some perfect ones are.

However no correctly done crimp is improved by soldering and most are damaged to some degree IMO.

[goboatingnow]

Originally Posted by Wotname

Yes and no, all dielectric grease is non-conductive but they have different abilities to flow under pressure.

Air is also non-conductive so perhaps we shouldn't let air get between the mating surfaces of terminations.

That’s the point of crimping for example it should produce a gas tight connection area.

In my opinion and I’ve been a professional engineer for 35 years , it’s does not make good sense to place any form of insulation ( even potential insulation ) between electrically conductive mating surfaces

If you want to do it properly , there are a range of conductive sealants.

Dielectric grease , should be confined to seals , o rings , exterior threads or used as a form of conformal coating. .

[goboatingnow]

Originally Posted by Wotname

While I agree that soldering a correctly crimp connection is a no-no, I fail see to understand the logic of saying a good crimp is impervious and yet solder can wick through it. Surely it is one or the other and mostly IME, good crimps aren't impervious although I know some perfect ones are.

However no correctly done crimp is improved by soldering and most are damaged to some degree IMO.

The crimp connection point should be gas tight , but the stranded cable elsewhere in the crimp isn’t sealed and solder will wick into the cable and extend beyond the crimp itself , creating a weak area. In a good crimp the solder brings little to the party and adds a failure mechanism that wasn’t there before. Make good crimps , not dodgy ones that then are bodged with soldering

[Dieseldude]

Originally Posted by Wotname

Yes and no, all dielectric grease is non-conductive but they have different abilities to flow under pressure.

Air is also non-conductive so perhaps we shouldn't let air get between the mating surfaces of terminations.

Grease in non compressible, so will form a relatively non yielding barrier between surfaces. It can be under hydraulic pressure. Air is compressible, so will not form a high viscosity barrier.


Nobody has mentioned the matter of surface finish and class of fit of mating surfaces. The too is a compromise. High surface finishes if an exact fit should offer superior conductivity. However this can be difficult to achieve. Insertion force on tight fits can make it difficult to impossible to mate and unmate connector pins. Allowing slight clearance decreases insertion force, but decreases conductivity. A lower grade finish will have more microscopic contact points, but perhaps not enough. Then there is temperature stability. The two mating parts can have diverse expansion and contraction, even if made of the same material due to uneven heat distribution across the joint. Of course the substrate which contains mating parts has a much different expansion coefficient, so connector pins can move microscopically. These may seem like fine points but can effect circuit operation. In doing basic troubleshooting, one must be alert to defects that may not be obvious such as connectors with "invisible" defects. These kind of problems can be the cause of annoying intermittent faults.



This brings in the matter of cleaning and examining dirty or corroded contacts. Material may have been removed, so reliability will be lost. For connections that use clamping pressure like top post battery terminals, this is not a factor, as inward adjustment compensates. But fixed size connections such a pins in a multi pin connector might loose reliability by scraping off corrosion or dirt with a knife blade or abrasive. Even slight misalignment of pins can be troublesome. If one must clean pins by means that removes material to get equipment running, it would be wise to replace pins or whole connectors at earliest opportunity. It is best to do minimal damage such as using fine emery paper on precision connector pins, perhaps it would be good to keep a bit of 400 grit aboard. Use special electrical contact cleaners, not general purpose solvents. Test cleaners on small non critical areas of plastic substrates to be sure that the material will not be dissolved.



Replacing pins generally requires special removal, insertion, and crimping tools that must be sourced from electrical suppliers. They may not be available from local marine and automotive shops. Equipment manuals should note tools required for connector servicing. In a pinch, I have used tubular items like metal pen refills to compress connector pin barbs to remove the pin, but one must be careful to choose improvised tools of a good fit. Some special tools are not expensive, but some might be costly. Money can be spent on special tools that are seldom used, and the boat can become cluttered. But how will one get the job done without them? Even the professionals, if called in may not have them in their kit. If investing in special tools, of course spare connector pins should be purchased at the same time.

[Manateeman]

The manatee crew bought a Temco hydraulic crimper on EBay for $100. Not a toy from China. Produces great crimps. They crimp cables for other sailors at a rate of six beers or one pizza per cable pair, so the tool has paid for itself.
Given fire in the electrical system is a expensive and serious issue, I think they made a good purchase. They don’t lend out the tool but it’s nice to do crimps for other sailors. You need heavy, good quality lugs and cable. They drink any beer.
Merry Christmas.
Captain Mark and his manatee crew.

[Dieseldude]

Good tools are generally a good investment. The pay back time of some can be faster than for others. Suppose that the Manatee purchased a good stock of lugs and cables to offer full and fast service. Good quality electrical connections are a must for safety and efficiency. Electrical hot spots on resistive connections can be a serious danger. So Sailers beware !

[Pete7]

Since we want the Manatee crew to live long and prosper, please don't give them pizza and beer, despite their pleas, it's just cruel. You wouldn't give your dog chocolate, well it's the same for the Manatee crew.

Instead as a reward for doing a crimp, offer them a nice, sharp tasting, green apple. Your actions could literally be saving a life with such a simple gift

[Dieseldude]

Originally Posted by Pete7

Since we want the Manatee crew to live long and prosper, please don't give them pizza and beer, despite their pleas, it's just cruel. You wouldn't give your dog chocolate, well it's the same for the Manatee crew.

Instead as a reward for doing a crimp, offer them a nice, sharp tasting, green apple. Your actions could literally be saving a life with such a simple gift

Good point for a long and healthy future. Glad that you mentioned it. A diet of excessive pizza and beer can limit one's sailing days, and days in general. All the talk about the safety aspects of electrical connections is fantastic. But let us not forget about the long term safety of dietary choices.