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Old 08-08-2020, 06:07   #1
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Battery-powered air conditioning

Hi all,

I’m very interested in a battery-powered air conditioning unit for our Pearson 424. The specs on the 24v 16k btu product from Termidynamica look amazing.

Is anyone here running air con with a unit like this without a generator? If so, would love to hear the details on your setup.

Thanks in advance.
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Old 08-08-2020, 07:24   #2
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Re: Battery-powered air conditioning

Quote:
Originally Posted by Peregrine1983 View Post
Hi all,

I’m very interested in a battery-powered air conditioning unit for our Pearson 424. The specs on the 24v 16k btu product from Termidynamica look amazing.

Is anyone here running air con with a unit like this without a generator? If so, would love to hear the details on your setup.

Thanks in advance.

Please post a link--nothing came up.


It's not that hard to do the math. Ah to run, battery capacity, and generation capacity. You will probably find that air conditioning anything more than the sleeping cabin for 8 hours is impractical, both in terms of batteries and solar/wind. Most sailors have barely enough power as it is, and AC is a big hit.


I can run mine for a few hours on the inverter, just enough to get out of a marina and into the wind in the morning.
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Old 08-08-2020, 07:29   #3
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Re: Battery-powered air conditioning

It is a simple math problem.
Realistically about the most that can be hoped for is to have a large expensive bank and a pretty big generator. The generator will supply the power and the bank will maybe get you through the night, so that you can then start the generator again to run the AC and recharge the battery bank.

The math won’t support what most want to believe, that is that it can be done with Solar and wind.

It’s not different than the electric propulsion argument

Average 16K AC will pull about 13 amps with water pump etc. that’s roughly 150 amps from an inverter assuming an efficient inverter. So you will pull 150AH from the battery in one hour, but don’t forget Perkuit which will make it more than 150 from lead acid.
Most don’t pull 150 AH overnight, and you just added 150 each hour to the existing load.

Many want to think that they can find a super efficient AC that will pull only half that power, and then they want to think it will run only half the time.
Good luck with both of those, I doubt a 200% increase in efficiency Is realistic, and the 50% duty cycle is only after everything in the boat is cooled down, and that doesn’t happen right away, but likely takes a couple of hours.

So yes it can be done, but it’s going to take a large pocket full of money, the AC isn’t the issue, it’s supplying the power that is,
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Old 08-08-2020, 07:50   #4
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Re: Battery-powered air conditioning

As others have said it really come down to numbers. Their website had multiple units so not sure which one you are looking at but one of them is 800W. Run that for 8 hours a day and that is 6,400 Wh (or 6.4 kWh).

You 'could' build a battery bank large enough to support that and existing loads using LFP. It wouldn't be easy or cheap but it could be done. That however would just get you through the night. You still have to produce the power that goes into the battery. Doing that daily without a generator would be tough. 3000W of solar might be enough in the caribbean for AC and all other loads on average but it will vary by day so realistically you would want something like 16 to 20 kWh battery to be able to ride out multiple days of reduced output. 3000W of solar and a 20 kWh battery would be extreme for putting on a boat. Even with all that unless you are ok with having to cut the AC off sometimes probably still going to want a generator and/or high power alternator as a backup.
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Old 08-08-2020, 07:51   #5
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Re: Battery-powered air conditioning

Thanks for the replies guys. I had a similar understanding of traditional marine AC power consumption. As I mentioned, the specs on their unit appear to be pretty groundbreaking... if they are real.

This is a 24v system pulling 11-38amps.

Here is the data sheet - https://www.termodinamicamarine.com/...data-sheet.pdf

“Power consumption is extremely low with a minimum of 250 watts and a maximum of 900 watts (11Amps to 38Amps).”
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Old 08-08-2020, 07:54   #6
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Re: Battery-powered air conditioning

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Originally Posted by Peregrine1983 View Post
Thanks for the replies guys. I had a similar understanding of traditional marine AC power consumption. As I mentioned, the specs on their unit appear to be pretty groundbreaking... if they are real.

This is a 24v system pulling 11-38amps.

Here is the data sheet - https://www.termodinamicamarine.com/...data-sheet.pdf

“Power consumption is extremely low with a minimum of 250 watts and a maximum of 900 watts (11Amps to 38Amps).”
900W for 8 hours is 7,200 Wh. Producing that without a generator would be "challenging". Not going to say impossible but it is going to require an impressively large battery bank and solar array.

There is nothing special about powering AC from a battery bank other than it uses a lot of power. It is the being able to produce enough and store enough energy that is the hard part.

I do agree that if you were seriously looking at something like this finding the absolute most efficient AC system possible makes sense. What makes it tough is even an efficient AC requires a lot of energy.
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Old 08-08-2020, 07:57   #7
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Re: Battery-powered air conditioning

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900W for 8 hours is 7,200 Wh. Producing that without a generator would be "challenging". Not going to say impossible but it is going to require an impressively large battery bank and solar array.
900w is the maximum consumption - I would assume this wattage is for startup and would never be sustained for 8 hours.
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Old 08-08-2020, 08:13   #8
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Re: Battery-powered air conditioning

Termodinamica A/C equipment is very efficient. A 60kBTU (240VAC) unit was installed in a 44' power catamaran and, once cooled, was able to keep the boat at a dry and comfortable 78F in a 90+F/90% humidity Florida summer while using 800-900W.

I have no direct experience with the smaller, self-contained, 16kBTU, 24VDC unit https://www.termodinamicausa.com/products/24v-unit but this smaller unit utilizes the same technology: titanium condenser, variable speed compressor, variable speed air handler fans, etc. and I do not doubt the claims.

This is truly breakthrough technology.
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Old 08-08-2020, 08:13   #9
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Re: Battery-powered air conditioning

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900w is the maximum consumption - I would assume this wattage if for startup and would never be sustained for 8 hours.
I would not assume that at all. It is a variable speed compressor. It can operate over a variety of BTU/hr outputs as needed but the power required scales with the output. Unless you get it in writing that it can (at your ambient temps) achieve 16K BTU/hr for 250W I would not assume that. It might not be 900W for max output but it likely isn't the minimum either.

If nothing else I would write to the company and ask them what is the likely power consumption for 16K BTU/hr output at your ambient air temp and water temp.
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Old 08-08-2020, 08:25   #10
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Re: Battery-powered air conditioning

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I would write to the company and ask them what is the likely power consumption for 16K BTU/hr output at your ambient air temp and water temp.
Or... I could post on an Internet forum to see if anyone has real unbiased numbers.
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Old 08-08-2020, 09:25   #11
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Re: Battery-powered air conditioning

I have looked into this a little bit.
If I was going to do any AC, I would pick up a doghouse unit.
Example: https://climateright.com/collections...34672044671128

I would condition one cabin only and would line all the walls of that cabin with at least 1” of insulation.
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Old 08-08-2020, 10:09   #12
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Re: Battery-powered air conditioning

I have heard of people running AC off the batteries. They had 1200AH of lithium batteries and a generator to support that to do it.

Me, I just run my 16,000 BTU air conditioner off the Honda 2200
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Old 08-08-2020, 10:51   #13
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Re: Battery-powered air conditioning

I was just on the Panbo site and saw this: https://tinyurl.com/y2myorw4
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Old 08-08-2020, 10:52   #14
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Re: Battery-powered air conditioning

You know Millions bought into fuel line magnets, and intake Vornadoes, and special carburetors and all kind of other claims too, and so far as I know no company was sued and out out of business, but you know these devices don’t work unless you believe the Oil Monopolies really do block technology as simple as a magnet.

Likely one of the better examples of efficient AC’s is the existing “mini splits” that are often Japanese and or Korean made, they are inverter Comoressors making them I’m pretty sure BLDC motors and they are infinitely variable speed.
The Toyota Prius AC is the same as is our AB style marine refrigerators, BLDC or “inverter”, all brushless DC motors are, but inverter brings marketing magic, like titanium or carbon fiber does.
They are pretty efficient over a simple old on/off compressor, but not by a whole lot.
Sure these things are capable of pulling very low current, but they do so by producing very low cooling, an on/off compressor does actually pretty much the same by cycling.

Where the increase in efficiency comes from is when they run at very low speeds they are essentially small compressors, but the evaporator and condenser remain the same size, and by increasing especially condenser size, you get an increase in efficiency.
Remember the old heat pumps? Small boxes with one side had what looked like a car radiator, well that was the condenser, newer heat pumps are often round, at least twice as tall and the condenser wraps around the entire thing, the condenser is several times the size it used to be, this lowers the temperature differential and the smaller the difference, the higher the efficiency.

Marine AC’s almost always give up evaporator size and to an extent condenser size in order to have a physically small package that will fit in a boat and not take up as much size.

Unfortunately there has been no great leap in efficiency, no 200% or greater increase, I really wish there had. It would go a long way towards solving a lot of problems we have now, it may even free up a lot of power to power electric automobiles.

You have to compare btu output to btu output and if you do there is no great difference.

There is an increase in efficiency in slowing down a compressor and running it 100% of the time as opposed to turning it off and on, look at the Adler Barbour new AEO controller that does that, but it’s not a huge jump, or we would all be extolling it’s virtues and everybody would have one.
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Old 08-08-2020, 11:06   #15
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Re: Battery-powered air conditioning

a64Pilot:
Comfortably cooling a 44' catamaran for 900W in a Florida summer is pretty breakthrough to me.

16kBTU = 1.33 tons; using traditional equipment, to achieve 1.33 tons of A/C requires 4.6kW(https://tinyurl.com/y2cywow9)
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