Would be grateful for any help.
Off grid system for my tiny house. I have 2x 380W solar panels in series, 60A Victron MPPT charge controller, and 2x 140ah Sterling AGM deep cycle batteries in parallel.
Its been horrible and misty for weeks now. I moved out a couple of days ago because the charge controller hadn't gotten past Bulk charge for about 5 days. Today I went back at about noon to disconnect the fusebox incase there was any slight power draw. Victron app at this point reported a bulk charge and a battery voltage of about 13.8. I went back just now about about 4 hrs later and now the app reports battery voltage of about 12.8V. Having never left Bulk charge.
Why has the battery voltage dropped when there has been no power draw? It has been a horrible rainy day but I thought it would still manage to put something in the batteries?
Second question. I would like to know how to tell the DOD of my batteries. I came across images like this:Which I thought might be useful. But then I noticed that when my batteries are being charged to Float state by my panels, the Victron app reports the max voltage as being about 14.5V, and min as 12.7/12.8. Does this mean min voltage is the more useful data point? This makes no sense to me because this is what the victron app is reporting now even though my batteries haven't made it beyond bulk charge for days.
Some screenshots incase this is helpful.
Less miserable weather:
Thank you all for any help offered,