This is part 2 of  How Far Do We Go  from a few months ago. I left off there with a working prototype of an Arduino-based odometer installed in my refrigerator car. That car was part of a starter kit and doesn't fit well with my theme right now so it is doing duty as a utility and testing car. It was the first car where I replaced the default hook-and-loop coupler with a knuckler coupler. It now is the transition between the starter set and a few of cars I have acquired that came with knuckle couplers. However, as I ended the previous post, that car didn't lend itself very well to having a display or a battery pack with easy access.  So I've torn that all out and started with a fresh design. The new design would have a four-line LED display, instead of two-line, to show more data and I decided to have a dedicated Arduino board. After trying a few combinations, I realized that the coal tender would be a perfect place for the odometer. It has a removable coal load wit...