Copprhead, what's ya plan for charging up the battery? Ya mention a mains charger
and boat motor
but say no solar panels
. If ya tied up in a marina, the mains charger is useful. Away from the marina, extension cords to the power station can only go so far.
The house battery on my boat is a 75 ah marine
starter/storage one, but only because that's what I got with the boat. I use a 20 w solar
panel which I move around the deck
to keep both batteries charged. With north Qld sunshine, it is more than enough to run my small load of lights, radio
, fan sometimes. But that is only for now.
My plan is to first replace the starter motor
battery and put in a smart isolator so it gets priority for charging. That is a little insurance
towards being able to get the motor started everytime. The retired starter battery will be put with the storage
battery as they are the same and I will use them as house batteries until they bust or I win the lottery. That will give me 175 ah storage
Eventually, I plan to have a deep cycle storage capacity of 200 ah with maybe 250 watts of solar panel. The motor will charge the starting battery and excess go to the house batteries if needed. The solar panel overflow will go to the start battery if needed, all automatic. This system should fit my life style of spending a few weeks every few months cruising the quiet places and the rest of the time having it closed up somewhere. Gadget wise, I will add a small fridge/freezer and extra fan or two to make the tropical nights more bearable. But that is my plans.
So, to suggest an answer to your question, if you are spending most of your time away from a marina and have the money
, replace the battery with a deep cycle one (or several) which will cover your needs and think about solar power as either a way to top up your battery if doing much motoring or a bigger solar power system to provide practically all of it if anchored in one spot.
On the other hand, if your power load is not too high, you may like to keep the old battery for a time but invest in solar technology which down the track you can connect to a new deep storage battery. In my experience, which is minimal, of living on the boat a few weeks at a time, I have found by having a go with what was there, as inadequate as I originally thought it was, I have had better ideas and insight into what will actually work as a solution.