I don’t get it...
I am buying my first boat and feel I’m being blitzed by people talking about inverters, power management systems, solar and wind power etc.
I’m not yet looking for specific advice, rather a beginners’ website or publication. Although I have rewired a house, everything I’ve found so far is beyond my experience. ANTONY BESWICK, via email
TONY REPLIES: I tried to write my Electrical Course Notes on TB-Training. co.uk for beginners. They cover most of the basic stuff and most importantly how to do a power audit (with your qualifications the calculations required are very minor) and battery capacity calculation. Do this before you think about inverters for much else than charging mobile phones and dry batteries, because it is easy to over-discharge and destroy a battery bank within weeks if you never get them well enough charged.
For a holiday boat, a solar panel of about 40 Watts will probably keep the batteries well charged during the winter and when you are away. For a liveaboard and when out cruising for several days you will need far more.
Modern alternators regulate at around 14.2 to 14.5 volts or more, so as long as the charging system is in good order, fancy charge controllers are not usually needed. Battery monitoring is important for a long battery life but a digital ammeter and voltmeter will do the job once you learn how to interpret them.
A big inverter will require large battery banks to minimise the volt-drop when supplying high loads, and it would be very inefficient when being used for small loads.