Charging a starter battery via solar

[Flying kurbmaster]

My charge controller (BlueSky mppt 30 or something like that) has that option built in, I can run a set of wires to my start battery and it trickle charges automatically, when it is charged I think it switches itself off, I still haven’t done this yet but will one of these days as the controller can do this. I also have a marine Battery switch, that has the option of one battery two or both which I used before getting this fancy charge controller and can still use. Which means if my house battery ran dead I could use my starter battery for emergency lighting, or if my starter battery ran dead I could boost it by turning the switch to both, I also think I could charge the starter battery by switching to both from the panels. I can also charge both, or one at a time from the alternator while driving by selecting from the switch.