24v AC systems. Anyone familiar?

[Tracyandkimo]

I'm looking at a '18 Lagoon 450. It has a 24v AC system, Lithium batteries and 2500w of solar. I am COMPLETELY unfamiliar w/such systems. Anyone have any experience?
It seems that the time we run the AC the most is on cloudy/rainy afternoons/evenings when the batteries might not be up to the task.
Any input would be appreciated.
Cheers, Tracy and Kim

[Lepke]

Usually 24v AC is to control relays and solenoids in heating and air conditioning systems, not directly power equipment. The 24v AC is generally supplied by a small transformer mounted on the main AC power panel. I use it on my boat for heating controls, windlass control and other relays with long runs. I have 120/240 AC available 24/7 thru my inverter.

[Tracyandkimo]

I may have worded my question poorly. I was more interested if anyone had experience running an air conditioner converting 12V to 220, which is how the boat in question is set up.
from the owner: " 7*360 Watt LG solar panels converting 24 Volt to 220 Volt to run air conditioning during the day"

[john61ct]

Yes that is not a 24V DC aircon system.

AC is 120V (US) or 220V power, best not to use that abbreviation for aircon, confusing.

So the aircon system is AC powered at 220V, which is the output from an inverter, fed nominally off the battery bank, but not for long without concurrent high-current energy inputs.

What are those inputs when you are seeing problems?

None of those numbers in themselves would imply anything relevant to performance, for troubleshooting you will need to specify make & model of the various components,

as well as other detailed info, symptoms, usage patterns etc.

[john61ct]

Solar energy does not give enough power to run a high-current load like aircon for more than a very short time per day.

You need shore power, a genset, or maybe high-output alternators while motoring.

[a64pilot]

One 16K BTU airconditioner will consume about 12 amps at 125 VAC which is about 1500W. 2500W of panels should be able to produce 1500W during periods of good sun.
So you could run one, wouldn’t be doing much battery charging, but you could run one AC in the middle of a good sunny day.

[Yatt]

You can run an AC powered by Lithium batteries. How long? It depends on the capacity. If you have 800Ah running on 24V means your capacity is 1600Ah running on 12V.

If your batteries are full, you can run a 16K BTU Air Con for nearly 12 hours. You do not need a genset or shorepower.

BTW - my L450F will be delivered next April in Les Sables and I am going to install the same system the owner of the above menetioned boat has. Lithium battieries, 3000 wp of solar and no generator like on my previous boats.

[john61ct]

Few boats have room for enough solar to run aircon.

Not to mention you have to stop charging, so everything else will be sucking off the bank. You will not be able to run the aircon off the panels **and** recharge a large bank at the same time, unless going to maybe 2-3kW of panels.

The batteries are just a "timeshift", you will get say an hour of aircon per 100AH of dedicated bank capacity, in addition to what you'd usually need.

Depending on weather, angles etc maybe 4-6 hours a day.

Lots depends on how big a space you're trying to cool, how thick and well sealed the insulation, gap between ambient temps vs thermostat.

Running off genny will be needed for sub-optimal conditions, so the large investment in solar+batteries+inverter in the end just reduces your genny runtime.

File under technically possible, but mostly impractical.

Best to just run your ICE sources long as the aircon is on.

No, best is do without, except on shore power.

[Steve_C]

Originally Posted by john61ct

Few boats have room for enough solar to run aircon.

"unless going to maybe 2-3kW of panels."

The original post said they had OVER 2kw of solar.

It is feasible but limited. It will greatly depend on how big of a bank you have (Usable AmpHours) and if you are just trying to cool the one part of the boat, like the master cabin, or maybe the salon but not both?

The main thing with this approach is a very thorough understanding of energy budgets, battery banks and solar. There is very clearly much more information that we would need to give any recommendations. If you go down this path you have a lot of learning ahead. Its very doable, but will require a lot of paying attention and managing it. If you find it enjoyable as many of us do, then by all means dive in, learn and enjoy.

However given your knowledge you would very likely be far better off with a generator.

NEVER let anyone convince you that this is a straight forward, black and white, yes or no kind of thing.

Best of luck

[John Holbrook]

you should also review the quality of the lithium batteries and supporting used and the installation. There is a fair bit of diy in some setups.

[Simi 60]

Originally Posted by Steve_C

The original post said they had OVER 2kw of solar.

:

Do you reckon rig and sail shading would knock those numbers down considerably?

[a64pilot]

Originally Posted by Simi 60

Do you reckon rig and sail shading would knock those numbers down considerably?

Not as much as you might think, besides unlikely they would be running AC under sail I would think. Something as big as a Lagoon 450 has a lot of space for panels.
Although they usually have incredibly huge generators