Silent Air Conditioning

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Monterey385

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May 28, 2015
280
Catalina 385 Atlantic Highlands, NJ
Our air conditioner, battery charger, and electrical appliances can be run by a Honda 2200. Even though the Honda 2200 is very quiet by generator standards, its still noisy when under load. Pretty much everything we have, other than the air conditioner can be run silently via two 175W flexible solar panels along with our 1800 W inverter and 400 Amp Hour House bank.

Which brings me to the point of this post. I was just staring at that Honda 2200 (which I love by the way) but thinking ... is there a better way. The Air Conditioner peaks at about 1800 W for a couple of seconds but draws about 500-600 watts when running.

Is there any practical configuration to run the air conditioner by solar and battery that anyone knows about for a sailboat?
 
D

dlochner

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Jan 11, 2014
12,049
Sabre 362 113 Fair Haven, NY
Does the air conditioner run on AC or DC? There are devices which dampen the start up surge that work on AC. To run an AC air conditioner on DC you'll need an inverter capable of handling the initial load.
 
M

Monterey385

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May 28, 2015
280
Catalina 385 Atlantic Highlands, NJ
dlochner said:
Does the air conditioner run on AC or DC? There are devices which dampen the start up surge that work on AC. To run an AC air conditioner on DC you'll need an inverter capable of handling the initial load.
Click to expand
Air Conditioner runs on AC. I think it already has a surge dampener but the surge is currently below the maximum for the Honda 2200.
 
kappykaplan

kappykaplan

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May 1, 2011
4,580
Pearson 37 Lusby MD
Monterey385 said:
Currently 400 Amp Hours but I would likely set the A/C up on a dedicated and separate house bank
Click to expand
Inverters are not efficient at converting DC to AC, so you are wise to contemplate an additional house bank. How will the boat react to the additional weight? How much additional solar will you need to add to charge the new bank?
 
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thinwater

thinwater

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Mar 26, 2011
3,569
Corsair F-24 MK I Deale, MD
kappykaplan said:
Inverters are not efficient at converting DC to AC, so you are wise to contemplate an additional house bank. How will the boat react to the additional weight? How much additional solar will you need to add to charge the new bank?
Click to expand
Quality inverters are 85-95% efficient. More important is the efficiency of the AC unit and what steps you take to reduce the load.
  • External sun shades on all windows.
  • Sunshade over the cabin when practical.
  • Insulation upgrades.
  • Only run it when the sun is down. Only during sleeping hours if possible.
  • Zones. Only the cabins when sleeping, only the main cabin other evening.
  • Electricity diet. Eliminate everything you can. LEDs. Less refrigeration (mine was gas). Turn things off when not in active use, even sailing instruments you don't need (which is most of them, most of the time).
Remember, there are three primary factors to power supply:
  • Surge.
  • Ah for the period.
  • The ability to recharge. This is going to be tough on a monohull. Perhaps 600-1000 W in addition to your house load panels, just for sleeping. Remember that with clouds, shading, and low sun angles, you can really only bet on about 5 hours times rated capacity. Most monos have trouble spreading enough panels just for house loads.
It can be done. I had battery powered AC on my PDQ. But it requires compromises.
 
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jviss

jviss

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Feb 5, 2004
7,089
Tartan 3800 20 Westport, MA
kappykaplan said:
Inverters are not efficient at converting DC to AC
Click to expand
I beg to differ. One can achieve upwards of 95% efficiency with inverters. The key is to size the inverter to the anticipated load. This can, by the way, exceed the efficiency of conversion of charging and then discharging batteries.
 
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Johann

Johann

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Jun 3, 2004
439
Leopard 39 Pensacola
Monterey385 said:
Is there any practical configuration to run the air conditioner by solar and battery that anyone knows about for a sailboat?
Click to expand
Yes, this is what we do. With a 945Ah 12V (12kWh) LiFePO4 bank and 1740W of solar. We are running two high efficiency Frigomar 120V air conditioners through a Victron 3kVA Multiplus. Since our diesel genset gave up we are using the backup Honda 2200 to supplement the solar array. But we make it thru the night on the batteries alone. The Honda is loud though, so I am eager to get my generator replacement scheme installed.

For your setup, you will need to figure our how long you want to run the AC, and come up with the required kWh. If you are going to have a dedicated system just for the Aircon that will make the math easier. Given what you have provided (5-600W running) and assuming 10h at 80% run time you need about 5kWh. That would be 400Ah of LFP at 12V, but I would consider 24V or 48V for better inverter efficiency and smaller cables. To generate that with solar alone you would need about 1000W of quality rigid panels.
 
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