It appears that t44 went down about 8:30 tonight (while we were at dinner). Vbatt shows that power crashed (last reading was 10.8V). I'm not sure why, and I guess I'll have to do a better job of monitoring power! (I had been paying attention to t0 and t47, that have larger-than-normal loads.).
P.S. It appears that this site has not been charging at all – either a bad Victron (or setting) or a bad connection to the solar panels. In either case, should be an easy fix. We'll want to swap in a set of charged batteries to jump-start it. This will also give me an excuse to set up the charging system in the base.