There is no escape from having to understand what your electrical
stuff requires. It is essential that you carry out an energy budget
for amps used on a 24 hr basis.
The important numbers are volts x amps = watts, thus if your 12v battery charger
is producing 12 amps 12x12 = 144w. however, if charging
it will actually be producing a higher voltage to try to make the battery accept the charge, and the battery will normally be running at a higher voltage than 12v even when not on charge (i.e. 12.8v means that the battery is at a good state of charge, 12.2 means that it needs charging, less than 12 means that unless it is a deep cycle, the battery is ready for replacement)
When carrying out an energy budget, it is better to work in number of amps/hour and to assume that the volts are 12v
For example tricolour light, 25w bulb 10 hrs use = 20 amp/hrs
Once you have completed this, you can size your battery bank properly, and match charging capacity to that bank.
These numbers for amps are not related directly to the size fuse or to maximum current draw - for example the coolbox may cycle on and off and while drawing 12 amps while on, if it is only on for 50% of the time, it is really only drawing 6 amps.
There are also a number of ways to reduce power requirements. Use of LED lights
, changing your inefficient coolbox, for one of the latest Waeco units that have a proper compressor
, and are designed for continuous use, but only draw abt 2 amps/hr etc.
A petrol generator
is a useful tool (I have one myself), but should really be considered as an emergency
back up to marina power. Running one continuously even in a noise
reducing box is a good way to upset neighbours.
A combination of sufficient solar panels
(perhaps with a wind generator
for those cloudy days) can normally be sufficient for most liveaboards provided they manage their power requirements. (ask Makai, they have lots of electrical
gizmos, but very rarely have to run their engine
for additional power, but they have 4 x 130 watt solar