The one thing that everyone wants on boats is free electric, well unless you have an 'eco' powered boat with solar panels and wind generators adorning every inch of the boats surface and moor in an open space to catch the sun and wind then I am afraid that there is nothing you can do except to generate it yourself using the tried and tested methods of a well maintained battery bank, and have a good method of charging said batteries, a good quality inverter to convert that power to 240 volts and if you can afford it a built in diesel generator which will either aid the charging of the batteries and also supply you with a decent amount of 240 volts, of course all this is less important if you are permanently plugged in to a shore line and rarely move your boat, but to do it properly costs money.
I lived on many boats since my first boat back in the late 80's, that was of course very basic and all I could afford was one battery and a Halfords type battery charger, if I was away cruising I relied totally upon the engines alternator to charge the battery and that was fine, when I Started living aboard I needed more batteries to cope with the extra demand that I placed upon the supply, eventually as my needs changed so did my boats and subsequently so did my power requirements, the last boat that I lived on had 6 domestic batteries, twin alternators, a battery management system, a battery management monitor(like a battery level gauge) a big inverter and last but least a decent built in diesel generator, I also had a smaller portable generator as a back up if everything else failed, needless to say that the whole system was costly but while I was away from shore power I enjoyed effortless power supply, I checked my batteries monthly for electrolyte levels, topped them up as required, I kept the battery terminals free from 'canker' kept the tops of the batteries very clean, all kept in a well ventilated area and most importantly I never ever let the batteries discharge below 12 volts, The batteries lasted for about five years and when the performance dropped to a level that I wasn’t happy with that is when I changed them for a new set.
My boating has changed massively since them days and now I only boat for pleasure but I still have the same disciplines as when I lived on a boat with regards to the batteries, just before I laid my boat up for the winter I carried out the usual checks on the batteries, levels etc and cleaned them and left them on my smart four step charger over the winter, upon visiting the boat recently they are all in excellent condition and ready for another seasons use.
we sell hundreds and hundreds of batteries a year, when we do a full engine service we include a battery check as part of that service as we believe it is an important commodity, If you look after your batteries then they will look after you and you should get a reasonable life span out of them, abuse them and be prepared to be let down by them when you least expect!
Its been a wet horrid today at Norbury, nothing exciting has happened, no boats have been seen moving so noting really to report about so until tomorrow.