Do not solder. Not a good idea. Ton of info on the net for reference. Tinning the wire is fine, but not a full solder joint.
A quality lug properly crimped will be the best solution. Non-insulated lugs are best.
What is your reasoning about not soldering?
Corrosion affects many electrical circuit throughout our country that have humidity levels above 35% most of the time
Soldering eliminates that
Corrosion is an issue with soldering. Very difficult to remove all the flux from a solder joint. The left over flux will cause corrosion over time. Proper crimp with a proper heat shrink (sealant filled heat shrink is best) addresses the corrosion issues.
Biggest problem is cracking. The solder does not do well in vibration environments and a car is a vibration environment.
Bad connections have caused my company millions of dollars in failures over the past decade. We put a team together that addressed the connection problems . The conclusion is a proper sized good quality lug properly crimped is the solution.
