Tell us about yourself!
The DS100 soldering iron will work directly with any drill battery in the range of 12V to 24V. No regulation circuit is required. However, as yrralguthrie has explained, the battery needs to be protected against over discharge. The circuit as described may work but may not be reliable, the zener should not be used in this way. The zener should go to a 10k (or less) resistor to ground. That junction should then go to the transistor base via a 10k-47k resistor.
I'm confused. This configurator seems comprehensive and has some nice features but it doesn't appear to store MY configuration info. It seems to me that after I drop in my pre-configured files and make further changes that MY changes would be stored in a data file somewhere other than configuration.h so that when a new Marlin version is released, configurator would be able to pull the new release, apply all of MY unique changes and then be ready for a fresh build. But when I try to change revisions it tells me I need to get rid of my changes. If it can't remember them what is the point of using the tool?, other than for the other nice features. Am I missing something?