New to the group please pardon my ignorance, I am trying to design a system for my sailboat

exrider8411

I appreciate any feedback that the group can offer

i plan on running my mini spilt ac which draws about 800-1000mwatts, computers and misc items which is another 500 watts average ..

I plan to use 2- banks of lithium iron batteries 9how many per bank would you suggest

i have enough real estate to mount 6 340/18v panels if needed


i need some help on the system 

thank you in advance

exrider8411

I might add I am also o-en to adding a couple wind generators 400-1000 watts  /?

mcgivor

To calculate the battery capacity needed there needs to be a time factor to determine the Kwh needed. The simplest way would be to run on shore power using a power recording device such as a Kill a Watt or similar as calculating the actual useage depends on too many variables, ambient temperatures, insulation desired setpoint etcetera.

Using an efficient inverter mini split with a high SEER rating and linear compressor, will reduce the overall battery capacity needed, they do however cost more but so do the batteries. What nominal DC voltage are you looking at? 

mike95490

Will this mainly be used underway or at anchor/dock ?
  Underway, the varying shadows from masts and stays pretty much will shut down any PV harvest, because the entire panel needs full sun.   At anchor, with careful planning, you can set panels where they will be unshaded.

All calculations you get from here will only be for unshaded  panels, any shade, even from a stay over a corner of the panel, will severely impact your harvest

Wind generators are noted for  being highly hyped as to their output.  Hopefully on a sailboat, you will have enough wind underway, for it to be useful

And don't forget, inverters are also made in models that run from 24V systems. Don't get stuck in a 12V box if you need lots of storage capacity

exrider8411

First of all thank you for your responses , I am open to suggestions on dc power,. I also read that may running two or three controllers on shoe rate circuits and panels to stop some of the shade panels? Again very open to your suggestions

mcgivor

Though I haven't ventured much beyond the LiFePo4 section of this site http://nordkyndesign.com/assembling-a-lithium-iron-phosphate-marine-house-bank/ they are dedicated to marine applications which are  not the same as terrestrial, you may,or may not, find useful information there, thought I'd pass it on as it could be of interest.

Dave Angelini

If as Mike asked you are going to cruise the boat, triple redundancy is the key to doing it long term with good results. Major systems need 3 ways of operating. Some systems can get away with one of the options being a plane ticket to bring back what broke. Propulsion, pumping, and firefighting need 3 or more. Just a dinghy motor bolted onto the hull will get you into the anchorage. You could sail in (If there is wind) also if the main engine goes down.

The LFP batts are a good choice, but make sure you do not end up with another chemistry that may price good but have increased danger. Need 3 ways to charge. Be very aware that a wind gen can easily overcharge a battery to death. Test everything 3 times, at least.

Make sure you can buy spares easily for all systems. It will not be easy to get them but it can be done. Get a Ham license. Even though this may sound old school, they are still out there and can be the only way in the back waters.

Running a split and electric refrigeration will be one hell of a challenge on a small boat. One way to make sure that the refrigeration keeps going, is to cool the box with a dual plate system or dual plumbed plate. This gives you an electric compressor and an engine driven for redundancy. The 2 types of compressors will give you a faster charge on days where you may run the split.

Hopefully you are going to a place (like Mexico) where the C19 has not ravaged the cruising options. I know 3 different boats that went thru hell recently trying to get in and out when their visa was up. Lot's of great memories here. Fair winds to you!