Battery Charger Sizing

[Maine Sail]

Is the starter bank size included in the equation when applying the 10% rule of thumb for determining charger output? I am upgrading from a TC TB10 amp and use a WM 50a battery combiner. Running a 50a starter and a 100a house (both AGM's). Thanks!

Unless the start battery gets drawn down then it is not entirely necessary to include it. A normal starting battery on a sailboat will be accepting 3 amps or less because it is almost always nearly full.....