Sorry for the newbie type question and I feel like a fool for even posting it. But for some reason I just can't wrap my head around this.
So I bought my 1996 238 used a couple years ago, and I do the maintenance that I can (I am no mechanic) and pay a great guy to do the rest. I live in Las Vegas, where HOA's rule the roost and almost no one can have a boat this size at their house so I keep her drydocked near the lake. The weather here has been terrible, well nice most of the week...then raining and windy all weekend. So that has kept me off my boat for 5 weeks now. I am a little worried that things will start to go wrong if I don't get her wet soon.
Rain or shine this weekend I am going to drag her home and clean her up and try to make sure everything works.
Last time I was out I switched the battery switch to 2 (it was an even day) and the ignition just clicked. I switched over to 1 and she started right up. Later on I switched to both hoping it would charge the low battery (was that right?) At the end of the day the weather got nasty and I didn't get a chance to check what was wrong.
So I will check the terminals first...but I want to make sure that the batteries (all 3) are charged. So here is the newbie question. How do I check them? If they are low and I plug into my AC at my house through the shore power cord how long should it take to charge them? And will it charge all 3? I have a backround in electronics (I mostly fixed small electronics), but it's been a long time. I know my way around a multimeter, but don't fully comprehend the electrical systems of vehicles especially boats. But I am willing to learn, so please point me in the right direction.
This is my ChargePro

Thanks,
_________________

Chris and Alicia
Las Vegas, NV
ALTIVA
1996 Four Winns 238 Vista Dlx 5.8Fi