What is your battery charging routine ?

I hope all of you had a merry Xmas . I can hardly wait for spring to get back out on the water but in the mean time I hope you can answer my question . I have always disconnected all the battery cables from the battery and set both batteries on a trickle charger for a couple days each month during the winter but is there a easier way that would allow to keep all the cables connected and still apply a charge to both batteries at the same time ? I just installed a C100 combiner last night and got me thinking about a easier solution of keeping both of my batteries charged all winter long from a single source of power and not having to remove all the cables .