I'm just back from a month of cruising, during which we had shore power
only six or seven nights.
I agree with Nick that fine tuning the inverter size to suit individual loads is really gilding the lily. I have 12v chargers for mobile phones and at least my laptop (but there were at times five laptops or more on board), but rarely used them. My Victron inverter/charger seems use something like 0.2 amps with no load which seems to me really not even worth thinking about if you have 420 a/h of batteries as I do. Someone always needed to plug
in and charge something so I just left the inverter on and it worked fine.
I think the main thing for electrical
happiness is to have enough battery
capacity and to have a way to get power into them efficiently every day. We generally got 24 hours of life on board with a full charge, and by the end of 24 hours I needed 230v power for something else anyway, so it worked out fine. I rarely let the batts get below 60% -- 65%. If I left all the electronics
on all night while at anchor
(in case of needing to make a quick getaway) together with the anchor
light, and if people were using toaster or nespresso machine or microwave on inverter power, then sometimes I would need to run the genset after less than 24 hours.
We were really lucky with the wind
and had no long passages under power. Nevertheless, even a little motoring out of or into a harbor seemed to always get the batts back up and the domestic hot water
So in sum, we really didn't worry about electrical
power this year at all. The key, I think, was the new Trojan batteries, with adequate capacity.
I used the small Honda generator
I bought as a backup only once. There was in fact no need for it while cruising. I will use it tomorrow to put a finishing charge on the batts before leaving the boat to fly back home.
One thing I did wish I had was a calorifier
loop from the genset cooling
circuit. Making hot water
was a fairly tedious daily task when there were a lot of people on board. I have a 1500 watt immersion heater, and I would run that off the genset, but that's very inefficient compared to just taking the heat out of the cooling