Quote:
Originally Posted by teejayevans
In the carib and anchor out, no, you have almost constant breezes and moderate temps/humidity. If in a marina or on the hard, then probably yes.
A 5000BTU AC will use ~6 watts, assume it runs half the time, 72 aH per day, you do the math.
Tom
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Sorry for the nitpick, but I believe you probably meant
6 amps. I haven't looked up the ACs in question, but that doesn't sound unreasonable.
To expound a bit for the original questioner, 6 amps at 120 volts (US standard small appliance voltage) is 720 watts. But you specified a wind generator, so your watts are coming out of the boat's 12 volt system at anchor. 720 watts at 12 volts requires 60 amps. So, running the AC directly off the wind generator means it must supply 60 amps minimum, ignoring conversion losses. However, you have batteries to soak up some of the load, so maybe you could get by with 30 amps average 24/7.
My personal rule of thumb for sizing minimum battery banks is to double the expected load, because you try to avoid discharging batteries more than 50% and you'd like to be able to go a fulll day without charging. Using Tom's assumption of 50% duty cycle, you're drawing 60 amps x 12 hours per day, or 720 ah. So, I'd add in about 1440 (720x2) ah of batteries dedicated to the AC.
Of course, the wind doesn't always blow, so add about 10 big solar panels. And sometimes it's cloudy, so a big genset would be nice.
You can see it gets ridiculous in a hurry.
But I think Tom's main point was that you don't really need it at anchor anyway. Since I haven't gotten down there yet, I'm inclined to take his word for it.
Wiley
PS - I studied this stuff a
loooong time ago, so excuse any egregious errors that crept in.
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