I've worked in an aircraft wire shop. Some of the older connectors were soldered including some high power ones that had 6 gauge wire. Specifications were written on how to do it. One of the big things that was not allowed was to have the solder wick up the wire too much. The way I did it was to quickly tin the wire with very little solder, and then heat the solder cup of the connector and put just enough solder in so that when you insert the wire into the cup with molten solder, the solder just goes to the top and does not overflow. You need to use rosin flux, and not just rosin core solder. It makes the solder flow better especially when you are tinning the wire. Use a iron with a flattened tip and not a round tip. The heat transfers better. The less time you are doing the soldering the less the solder wicks up. Better heat transfer speeds it up. Another tool we used used a very low voltage high current to flow across the connector being soldered to heat it with resistance. You had to be careful to keep the tips clean so the current would flow enough to properly heat the joint.
I am glad those soldered connectors are going away. It's a real pain in the neck, I like the crimped connections much better. Still when the engineers decide to ude an older piece of equipment for the test, I end up soldering again. If you screw up one wire and have to cut it, often times you have to do the whole connector over, because the wire lengths are no longer the same. Sometime if you are lucky, you can reroute the wires in the bundle to make the shorter wire long enough again, or you just have to cut all the wires, re strip them all and start over.
2013 S model with quick charge package.
AV 30 amp level 2 EVSE, Bosch PowerMax 30 Amp EVSE, EVSE upgraded EVSE.