How dangerous is soldering to 18650s? Is the best approach to sand them with low grit sand paper first to make it easier to solder to? Is it better to use a higher temp to do it quick or a lower temp to prevent too much heat? What should I do to cover the terminals after I solder to them to avoid shorts as the terminals are pretty large? How can I test to make sure they're working after I wire them to the protection circuit before I hook it up to the console?