Snow petrel battery power

Two solar panels getting iced up.. Not much charge going in..

Yesterday at lunch break my fellow builders and I discussed batteries and solar panels and the like. We talked about using wind, solar and the other option of trailing a water generator. At this point I should come clean and reveal that my fellow builders are all sailors as well. My dad (head honcho) with NZ maid, two of my brothers with assorted boats like the Proa (see the videos page.. Top left), And another friend who is rebuilding and living aboard a 34 footer.

Living aboard a boat for any length of time (away from the marina) quickly shows that power in a battery is your lifeblood. And there are plenty of vampire like appliances to suck this lifeblood away, If you are silly enough let them get anywhere near your batteries.

I used to manage quite well with one 40 watt solar panel, It kept the basic lights running and the radio playing, or occasional bit of watching a small LCD TV. But things could get a bit desperate on cloudy weeks, and I reckon the 50% discharges haven't done my batteries any good.

I had a wind generator (an Air Marine) on the last boat, but found that athough it worked well in (Windy) Wellington and did OK at sea, It was not as good as the solar panels at running a base load, I either had no power or far to much, In general the average good anchorage was too gusty to get any useful power. The 40watt solar panel was a huge improvement, trickling in a good reliable charge most days. With my small two battery system I cannot store the huge amount of power that the wind generator puts out in any decent wind, So after a couple of hours of charge the wind generator was switched off for peace and quiet.

So if I spend the money on another wind generator it will probably be something like the Rutland 504 which puts out a pitiful amount of power but is small, quiet, safe and works well in strong winds. Most of the bigger ones have to be shut down for safety in gale force conditions, right when the solar panels are often under cloud, and when you don't need any power issues. Saying that, in some places like the trade winds or with a good reliable sea breeze wind generators may make more sense?

My father uses a tow generator at sea and loves it. It powers the autopilot and the small fridge, and works well whenever the boat is moving. This was our backup for the trip to Antarctica, but we didn't need to use it because the solar panels provided plenty of power. Obviously the tow generator only works at sea, and not at anchor.

The system that works for me now is two 40 watt panels on tilting mounts and with a top quality regulator/battery monitor and two combined starting/house 70 amp hour batteries. The batteries are standard wet cell lead acid, They are not sealed, so I can  top up the fluid and check them with a hydrometer every so often (actually not often enough). They are cheap and seem to last well even given considerable abuse (I nearly boiled them dry last year), They are stuffed now, after 6 years, and are only on life support due to the solar panels. This is a good innings (I think three years is about average) and I feel I have got my moneys worth out of them. At this stage the jury is still out on the sealed AGM and Gel cells. I think I will just use cheap standard batteries again, the modern charge regulators pulse charge them, equalize them occasionally and generally keep the batteries much happier than in the past, extending their life considerably.

If you look at this link It will give you some idea of just how hard it is to run a large complex boat electrically. I avoid alot of these problems by being a power control freak, and by having minimal power draw, no fridge/freezer, no wanky wind and boat speed instruments (can draw more than you think), no big chartplotter, and a windvane rather than autopilot, It Is a good feeling to know I can cut my needs down to just one small light and a book.

I have a third 40 watt panel to install, and I will probably put in a standalone engine start battery, With this in place and new house batteries I should have plenty of power for my computer.. With Modern LED lighting I may even have some power to spare..