Dewey, You are of course, correct. I was addressing the voltage drop from my suspected cause.
Transformers have a unlabeled and unspoken capacity called "Stiffness". That is, they tend to droop the voltage as they approach the rated output. MTH bricks have good stiffness in that they do not droop much. I can't speak specifics on others but it is a known factor. The cheaper the transformer (the actual transformer inside the controller) the worse the droop is.
That drop to 13 volts is probably a combo of all these issues. Droop, needs another power connection, and needs heavier wire from transformer to near the track.
Making lots of short blocks and alternating them between phased transformers will spread the load of a long passenger consist and engine onto 2 or more blocks. If you have 3 Transformers, you can spread it across the three transformers by using fairly short blocks. Just tie each transformer to the next block in order, 1, 2, 3, 1, 2, 3... Then each transformer carries part of the total load. This does make for a wiring nightmare, Label or better yet, color code the wires. You will still eventually overload if you run multiple trains as the trains will be hitting blocks loaded by other trains.
And good circuit breakers or Fuses on each Transformer output and a bipolar TVS across each transformer output is a very good thing.
I will now post this before it becomes a dissertation
