If you are planning on running A/C off battery power you best have lots of them, and big ones. Batteries and inverters are not a good power source for something as power hungry as A/C. A/C and a 120 VAC fridge puts you in generator territory.
My son in law has a 2002 Rinker with 2 large batteries that powers his fridge and his ac for 2 days. The batteries are large gel cells I cant find any info on. His boat was rigged this way when he got it and yes it has keep the system running for 2 days. This is all that will be required as most of our use will be start of one day late till late next day. So about a day and a half
So I guess you need to copy his setup (including identical air and fridge). Battery capacities are listed on the label on the battery. A group 27 deep cycle for example will provide about 180 reserve minutes at a 23 amp draw. That's three hours. You need to know the current consumption of the the a/c and fridge to make a reasonable power consumption determination.
Ac states a 6.9 amp-hour draw running and 21 at start up. Do not know the fridge yet. I figured 4 225 6v batts will provide 900 amp hour. Should run both for 15 hrs maybe.
Are you not forgetting about the conversion from 12 volts DC to 120 volts AC? The current draw of 6.9 amps at 120 volts means the current provided by the battery INTO the inverter must be a factor of 10 higher or about 70 amps. The inverter is 85% efficient so tack on another 15% for losses in the inverter. You are now near 80 amps and that does not even consider the 21 amp starting load or the fridge. Then you made one additional math error. Two six volt batteries in series providing 12 volts does not "double" the AH rating. That only happens if you "parallel" the batteries and you still only have 6 volts. So you really are down to 450 AH with four six volt batteries (two series pairs which are then paralleled.)
Your right I did mess that figure up. I will search for the appropriate battreys like the ones in the Rinker. Thanks for keeping me from making a huge expensive mistake.
In 2002, DC powered AC units hadn't been developed yet. Therefore I find it interesting how you switch over seamlessly from the 120VAC that runs it on shorepower to 12VDC that the batts provide. Yes, you may be able to use an inverter, but it would have to be a pretty powerful one to kick start that compressor...
The boat has a AC powered unit with a large inverter. It has 2 batteries I don't know how they are wired. It only charges on shore power and then changes to inverter as soon as the boat is unplugged. I have been it the boat on the water with a nice cold cabin to sit in. I was just trying to figure how much power was required to pull this load. Yes I understand it will require a lot of battery which is weight. But on a 26 ft boat generators are to loud and just not what I want
