Thanks, I appreciate the info! I do have a couple of Nigel Calder’s books. A lot to learn for sure!
The best conductor of electricity is silver, but I doubt you are going to find any nuts and washers made of it.
Brass nuts and washers are the best compromise of conductivity, strength and availability. But I often use SS because I have a bunch of these in various sizes and the surface area is relatively large and the distance is tiny, so the worse conductivity of SS hardly matters.
But I only use them to attach a spade connector to a screw terminal, never to attach two wires.
David
Good photo of how not to do it. Just to clarify about washers, do not put them between any connections but it is ok to put one on top of the connectors under the nut or bolt head since current will not be flowing through the washer that way.
..... In these situations, current travels through both nuts to the thread rod.....
Ted
True, but the current flowing through face contact will be many times that of the connector to stud. Think about the tiny contact patch between the round hole and the sharp edge of the threads. Not to mention the oil, grease, paint and associated junk that find their way into these spaces. Same for the outermost nut: several more areas of added resistance compared to an innermost direct face to face contact.
You're mistaken. Contact area on threads of bolts and nuts isn't the "sharp edge", it's most of the back side of the thread. Depending on the number of threads engaged between the bolt and the battery socket (or nut), the electrical contact engagement may be greater with the threads than the bolt face.
Ted
@gonediving #18:
The photo is unclear regarding the wire nut but, per ABYC Standards wire nuts are not compliant and we are permitted to stack no more than four terminations.
I just installed an EGT on my Yanmar, and the pigtail from the pyrometer came with a ring terminal, a nut and bolt, and a heat resistant sleeve. The instructions specifically stated that the connection to the boat's wiring should also be a ring terminal with a proscription against shifting to a butt connection. Only time I saw such.