I have this wild idea of powering a window unit from a battery bank. not 100% about how i would charge the batteries but just a crazy idea. Any suggestions on how i might be able to do it?
U are right . Look at the power needed. Look at the wats needed for unit. Now divide it by the voltage power. The battery unit will require another 40% which is the loss in the battery charge system.volta times the current power in wats.
One issue you are facing is that anything with a motor is going to have induction power needs, which need a lot of extra amps to get them going, so you will need extra energy and amps to kick the unit on. For that, I wouldn't let the unit cycle because the kick-on's would really eat battery faster. Second issue is that converting electricity to chemical battery energy is a loss of energy, not to mention the conversion from DC to AC. The conversion rate is around 85%, so you lose about 15% unless you spend top dollar on the equipment to get you closer to 95%. All batteries also suffer from some sort of degradation effect so you have to keep them constantly charged to keep them ready, which if for frequent power outages would be a good idea, if for fun kind of expensive.
This replaced into in automobiles and Transportation so i assume you go with for to place in the A/C in a automobile. that's in simple terms a wild advice, yet perhaps you will desire to put in the fashion of A/C it is made for shuttle trailers or custom trucks. they are the type that mount to the roof. i'm extremely particular they run on 12 volts.
Here in Hurricane prone areas, there's the problem of a sustained loss of power causing not only a lack of AC but the spoiling of food in the refrigerator. Although a modern refrigerator only consumes an average power rate of 150 watts, you need to use a 1,500 watts to 2,400 watts generator to run your refrigerator due to the peak power use of starting the compressor (AC presents a similar problem). One trick that I worked out was to use a Xantrex battery/inverter power back (often erroneously called generators) which can run a refrigerator for four hours and plug in the DC line from a small camping Honda portable generator to charge the battery pack (less than 1,000 watts) essentially using the batteries as a capacitor to handle the peak loads. You could probably do something similar with a window AC unit. I cleared the details of how this would work with Xantrex pre-sales technical support but I found that the Honda generator was wired such that only a fraction of the generated power was available at the DC outlet with most of the power being available at the AC outlets (it looked like it was still enough though).
Wouldn't it be a better solution to reduce your need for AC in the first place? By changing your building slightly - installing radient reflectors, increasing insulation and interior thermal mass, and by fan cooling of these structures at night - you build up a cool store you can tap into during the day. This would reduce your base load - and be money well spent. Don't forget evaporative cooling - it's how the original refrigerators worked. That said - use a battey bank to power a small compressor - but make sure the heat is dumped as efficiently as possible - like into a pond with a water fountain. This is your own private cooling tower ! Good design reduces the need for energy consumption.
