I put in two of these batteries brand new.
Buy Autocraft Marine 12-Volt Marine/RV Deep-Cycle Service Battery 24DC-1 at Advance Auto Parts
Boat is a Bene 32s6 with Volvo Penta engine.
The owner left the ignition switch on for about 24 hours and it drained the battery to about 60 percent.
I trickle charged it at 2 amps with a shore charger for maybe 4 hours max.
Then motored about an hour and a half to a mooring.
The next day I 24 hours later I check the voltage.
I was expecting maybe 80 percent charge 90 at best.
The charge was 12.9 volts.
Any explanation for this?