My former post was on the unwanted heating up of a cigarette lighter and it was determined that there was too much resistance in such a connector, so switched out to the XT60 based mainly on Jeff Liebermann's recommendation. I initially had great difficulties with my various soldering irons on hand heating up both the connector and the 12 ga copper wires enough to get an acceptable connection, so proceeded to order a brand new 60 watt temp controlled iron and some flux. Well, I'm happy to report that all is well. I have been pleasantly surprised by how well the combination of the iron and flux are working and all connections, while still delayed a bit, are being satisfactorily made and I no longer have lack of connection, melting, or cold solder concerns. Oh, and I have been working with silver solder too as the standard had not yet arrived.
Apparently, my other irons on hand either didn't have the correct tips, were too old to heat up correctly and/or lacking the additional flux all worked to disadvantage. I must say that this 60 watt iron heats up faster than any of my other irons. It is a pencil type and ready to go in about 15 seconds, where my other pencil units always took several min.
Thanks again to the group for setting me straight.