Monitoring the charge level of a 24V battery bank

Hello! Am using a Victron MTTP controller to charge a 24V battery bank from a solar array. The system has no BMV for now, but I see I can monitor the battery bank voltage level on the Victron app, and note that it is at 25.92V when fully charged with no load. Have been told I can monitor the charge level just by watching this voltage level, which sounds good, but am not sure what voltage level I can allow it to descend to? Important question, because am on a boat and the battery bank runs the electric motor - sort of crucial! Am about to launch her on a river expedition, so hoping I can have a quick answer that won’t involve any more installation - am out of time for now! Many thanks, wonderful people!

Should add that the battery bank is 4 12V lead acid 110 giving a max of 220 amp hours each, running a Torqeedo Cruise 2 FP drive @ 2400 watts. The Torqeedo control-board monitors the battery voltage too and reports a slightly lower voltage (25.7V) when they are full with no load.

You can estimate the battery state of charge using the voltage but it can be very difficult as the load varies and temperature changes.

The Victron BMV takes all the variables into account and is the only way to get accurate an SOC reading