The
Crown website calls this a marine starting battery, a small gp24. It lists reserve capacity of 65 minutes at 25 amps. As far as I know, there is no tried and true method for converting RC to amp hours. Unless you are plugged in every night or have a generator to run quite often, you won't get far. Without knowing battery capacity you can't really set P3 or P2. P1 should probably be 14.2 or 14.3 if your converter has an absorption mode of 14.4. A guess for P3 would be 50 to 70 and 1 for P2. This will get the meter operating, but the numbers won't mean much.
Look into the twin 6-volt setup sooner rather than later.