So far, yesterday the battery voltage was 12.95.
12 hours later the voltage was 12.95
12 hours later the voltage was 12.93
12 hours later the voltage was 12.93
12 hours later the voltage was 12.91
So I hope the relay I replaced was the culprit that killed two batteries in three weeks. I tested the relay I removed, there are four tests and I performed three, and it passed the three tests. I have to make up some wiring to do the fourth test.
I am going to leave the battery disconnect in place and put the extra weight out of my mind.