Why do I always have one dead battery?
 

On my 2nd 232 Islander now and no matter what I do I can't ever seem to have two charged batteries. Anyone have a solution???????

Did you check to make sure you alternator is supplying the proper voltage? If not, that is where I would start. Make sure there is big load on the system as well. (turn everything on) You should see 13-14 volts, 13.5-13.7 is ideal.

If you did this already then forget I mentioned it.

How old are the batteries? They do take a beating on boats and with all the jarring the plates tend to break down a lot faster. So it could also be a simple battery change.

I just typing out loud since there is not a lot of information to go by.

Hope this help or if you already tried this then sorry I couldn't supply the information you were looking for.