Well, after Intensive Investigation
, it appears that the source of my problem was the Battery itself. It was just plain, old tired, which may cause inconsistent battery charge holding times. I changed the Battery and I only lost a couple of percentage points over night. I will continue to observe, as I only put the other battery in the other day. But so far, that appears to be the cause.
I do switch between 2 batteries, but sometimes I don't switch, and I just charge.
The previous battery may have had a lot of cycles.