The reason for not soldering has nothing to do with the electrical properties.
Originally Posted by elton
When a thick multistrand wire is soldered in the way we are suggesting then the solder will form a sudden stress raising location at its surface.
This may not be a problem in this instance though to get it right the way Vic suggests is not for the inexperienced and faint hearted. The job is made difficult also as the lug has a vent hole in it through which the solder will escape unless plugged as the solder will be in the lug like a pool of mercury trying to escape.
Yes it can be done but might take the inexperienced a few goes before the plug of solder totally attains the correct temperature by which time the plastic will probaly have gone up in flames. Not even enough wire unless a big loop is formed to slip on heat shrink to use to cover the damage to the insulation....Yep Vic can no doubt do it and yes I have installed systems in this way but not where there may be vibration at the lug as in this case the wire will fail, IE lugs on the big terminal of starters.
Eastern Scotland and beyond.