What is better battery connection?

[chris07732]

For marine use, which battery connection is more maintenance free: The clamp on automotive connector, the automotive side connector with ss bolt or the marine type top connector with ss nuts/lock washers. I'm finding over years that I develop corrosion issues under the red/black rubber insulating covers with the latter two methods.

[mike d.]

The better method would be for the primary cables that go to the selector switch to be attached to the lead cable studs. Any ancillary wiring would go the the s.s. studs. This would give better voltage to the start, and main electrical system, and negate most of the voltage drop, caused by extraneous components.

[Terra Nova]

Stainless steel is a poor electrical conductor; instead use nickel plated bronze.

[Colin A]

Steve D'Antonio has an article about this on his site.
Battery Terminals | Steve D'Antonio Marine Consulting

In navy applications here at work we use the flag style terminals (coppers tabs with holes you bolt terminals too) but I think the best terminal will vary by application.

[sailorboy1]

Originally Posted by chris07732

For marine use, which battery connection is more maintenance free: The clamp on automotive connector, the automotive side connector with ss bolt or the marine type top connector with ss nuts/lock washers. I'm finding over years that I develop corrosion issues under the red/black rubber insulating covers with the latter two methods.

I bet they all really are about the same. Are you using any dielectric gel on the connections?

[neoxaero]

I've always used military style terminals for all of my battery connections across the board. For battery cables I've used tips that you solder on. You can heat up the tip to melt all of the solder then stick the cable in. I follow it up with some heat shrink that has glue in it so it completely seals up the cable.

I've seen cables that I made 13 years ago that still look like brand new inside (tips are corroded but they clean up easy enough)

[Terra Nova]

Originally Posted by neoxaero

...For battery cables I've used tips that you solder on. You can heat up the tip to melt all of the solder then stick the cable in...

Very bad tech. Battery cable terminals should be properly crimped on--no solder.

[exMaggieDrum]

The automotive style that clamp to fat barrels sticking up from the battery are the absolute worst type of battery/battery terminal you can have on a boat. They are hard to keep tight in the vibration rich boat environment. Most are tapered from narrow at the top to wider at the bottom. The best kind are those that you bolt to, with flat washers and lock washers, or aircraft style lock nuts. Contrary to what some have said recently on the forum, you can use stainless hardware provided you mate the cable terminal to the battery terminal directly, i.e. do not put stainless between the battery cable and the battery terminal. All the current goes through the cable terminal and does not go through the stainless washers or bolts. I prefer copper/bronze bolts for use on batteries with female threaded holes though.

Cables should never be soldered to terminals. The vibrations on boats will make them brittle and break. Perhaps not for some but it happens enough to be considered completely unsafe and non-compliant by the ABYC. Soldering of large cables is also far harder to do than most cruisers are capable of doing. It is very difficult to get full penetration of solder and a good solder connection to the terminal with large cables. If you heat it all hot enough you will also melt the insulation on the cable. The good experience of one boater is not sufficient evidence of it being a good practice. IMHO.

[Sailor Doug]

Originally Posted by sailorboy1

I bet they all really are about the same. Are you using any dielectric gel on the connections?

Why would you use dielectric grease?


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[chris07732]

Thx everyone. Good responses. I'm setting up a forward battery compartment for my new bow thruster and the info/choices provided is very helpful.

[Frankly]

Might want to take a look at what one mfg suggests.

Just made a new set of battery cables for Cbreeze. Used crimped tinned copper battery post clamps. Drilled a small hole in the end of both the lugs (for the switch end) and the battery clamps. Finished them off with solder until the end cavity and hole were filled. Sealed with heat shrink.

Don't think typical vibration issues with soldered connections apply to battery cable size connections in any reasonable set up.

[Terra Nova]

Originally Posted by Frankly

...Don't think typical vibration issues with soldered connections apply to battery cable size connections in any reasonable set up.

And you'd be wrong.

[Frankly]

I would say we shall see going fwd, but the technique that I used does not allow the solder to wick far enough down the wire to create a hard spot. The crimp probably forms a block for the solder wicking.

I do have one data point of interest. On the bonding system on Cbreeze I have crimped/ soldered most of the terminals as they are often in the bilge areas. I have 4 connections to the Yanmar motor mount brackets ( 2 on the port and 2 stbd). Now that is a connection that is subjected to vibration. Watch them like a hawk. 11 years and still none of the 4 have broken.

[Maine Sail]

Originally Posted by Frankly

Might want to take a look at what one mfg suggests.

Just made a new set of battery cables for Cbreeze. Used crimped tinned copper battery post clamps. Drilled a small hole in the end of both the lugs (for the switch end) and the battery clamps. Finished them off with solder until the end cavity and hole were filled. Sealed with heat shrink.

Don't think typical vibration issues with soldered connections apply to battery cable size connections in any reasonable set up.

That's really not some of Trojan's best work. It almost seems like an intern put that one together. "White papers" would typically employ scientific methodology and include such things as details.. They are also usually written in a scientific peer-review structure & format.

What is "a high rate discharge" ?

How many amps?

What crimp tool?

What brand and model terminal?

What gauge wire?

Was the terminal designed/sized for that gauge wire?

How long was the high rate discharge applied?

Was the duration of "high rate discharge" equal in each thermal image?

Did they start from the same baseline temp for each test?

Had the lugs and battery stabilized at ambient room temp all yielding similar temp references on the thermal imaging camera before the load was applied?

What type of wire?

What type of stranding?

What were the terminals torqued to?

Were the lug holes the same diameter as the battery stud?

Were they copper terminals or aluminum industrial terminals?

Was there a control tool use as a baseline gold standard for comparison?

Were the crimps tested to any standard such as UL486A or Mil-T-7928?

Were the tools properly calibrated before the testing?


If they are going to offer advice, as a large public company, they really need to do a much better job. The list above just scratching the surface of what a scientific white paper would include.

I too own a thermal imaging camera and none of my crimped connections exhibit that type of heat but I use a crimp tool from the same manufacturer as the terminals. My tool also exceeds Mil-T-7928 as is confirmed & tested with a digital load cell yearly for 2GA through 4/0.

With use of the correct tools, and I can almost guarantee those crimps were not made to any UL, SAE, or Mil-Spec standard, as they should be, the thermal images do not look like that.

I've run my Flir on cheap Chinese crimp tool crimped lugs, hammer crimps and those made by my FTZ battery lug compression crimp tool and there is a wide variation in performance.

That said the average hacked-together lugs I see on boats, hammer crimps, pliers, and Chinese Harbor Freight quality crimps probably do look like that under a Flir and solder may help.

[RaymondR]

Did not realize I was such a dumb old bugger.


I have soldered connections on my boat, including all the battery cables, which are 28 years old and unlike many of the crimped connections have never had a problem with them.


If I want a connection to be really reliable and not wick water into the multi strand cable I solder on the connection then heat shrink it and squeeze in a shot of hot melt glue. Sometimes I have to reheat with a hat air gun to get the glue to flow and the heat shrink to fully shrink and squeeze out the excess glue. I have never had a failure of a connection made in this manner.


Being very much a suck it and see sort of bloke I did not realize I have been screwing up for all these decades. Anyway I am too old to change and will continue to crimp and solder and heat shrink and hot melt when I want truly reliable connections.