Can batteries operate 9000 btu A/C ?

[Al B]

Just pulled 250 lbs of non working equipment from port side
Big item was a 5 E Kohler generator that needs rebuild
A/C from dockside
Deck refrigerator a rust bucket not operating , Removed
Plan is too install a cabinet in refrigerator opening
Less weight , more storage . I was happy too see it go
Boat is a 30 ft cruiser ,
Prior too generator / refrigerator removal boat never sat even.
Noticeable lean too starboard ,
Cant find out why ? still working on it
250 lbs liter on port side.
Boat is leaning more too starboard ,
SO obvious got a call from marina .
Rather then install another generator , can a battery bank
inverter, panels , run a/c few hours ?
Sand bags , concrete temp fix , will balance but will look like crap
Any ideas ????

[john61ct]

Answering the title question specifically:

Aircon needs shore power or a decent size genset.

You could wear out a very large expensive battery bank in order to get some time-shifting,

call it 100Ah capacity per hour

IMO benefits not at all worth the cost, still need the mains or ICE power to recharge, solar will **not** be enough.

[mickt243]

my boat (30 foot sea ray cruiser) has no genset. 460Ah of house batteries. we do have a small air con, about 8000btu from memory - the batteries will run it for about 4 hours (along with the tv and a few led lights) - so johnct61 is pretty much spot on with his prediction of 1hr use per 100Ah of battery..... as mentioned its also not real good for the batteries to be run down that far (essentially 100% discharge) - especially if you cannot recharge them straight away..... either much, much more battery (preferably LiFePO4 or LTO) and lots of solar, or shore power....


short answer is, yes its possible BUT...

[john61ct]

The bigger the bank the harder to fill back up.

Especially if you want to run aircon at the same time.

Best to just run the genset while the aircon's going.

[Q Xopa]

Generally I would agree with the comments about needing a Generator or shore power to run Air cond.

However there are some clever people pushing these boundries.

https://youtu.be/rjVIxqTHahY

Basically this guy, and others, runs an extremely efficient 24 seer (Seasonal energy efficiency rating), 9000 btu mini split unit. He has his RV well insulated and running LFP drop ins (I think).

His unit draws a max of around 52 Amps at 12v, much less when at the Setpoint.

So like fridges if you insulate your cabin well it cuts the duty cycle.

So as mentioned this is still definately not a small solar or battery set up.

They are not cheap but 40 seer units are available.

This is not mainstream, simple or cheap but is getting more doable.

[B23iL23]

Check out

https://www.youtube.com/watch?v=yjK1Gi_u6ss

They run an a/c off a lithium battery bank. Key is a "choke" or soft start. The A/C will pull a lot of amps on startup but then drops once running. By using the soft start you can limit the total amps the a/c can pull and so stop your ac circuit tripping.

[NYSail]

Originally Posted by Al B

Just pulled 250 lbs of non working equipment from port side
Big item was a 5 E Kohler generator that needs rebuild
A/C from dockside
Deck refrigerator a rust bucket not operating , Removed
Plan is too install a cabinet in refrigerator opening
Less weight , more storage . I was happy too see it go
Boat is a 30 ft cruiser ,
Prior too generator / refrigerator removal boat never sat even.
Noticeable lean too starboard ,
Cant find out why ? still working on it
250 lbs liter on port side.
Boat is leaning more too starboard ,
SO obvious got a call from marina .
Rather then install another generator , can a battery bank
inverter, panels , run a/c few hours ?
Sand bags , concrete temp fix , will balance but will look like crap
Any ideas ????

Small boat to have that size gen. Bet P.O. put counter weights somewhere.... keep looking. May be glassed on.

[Sailmonkey]

Can you? Yes.

Would it be cheaper to rebuild/replace the generator? Yes.

[tkeithlu]

Can you? Yes. Very briefly. Fix the genset. You'll love being free of energy limits.

[a64pilot]

It’s just a simple matter of scaling, nothing else.
Increase your battery discharge rate by a factor of ten, then if increase the bank size by ten and the charging capacity by ten, then of course you can do “it” whatever it is.

However it’s almost guaranteed that in order to increase the Charger capacity by enough is going to require you to run an engine, to drive either monster alternators or a generator.

Most choose to skip the huge, expensive battery bank and just run the generator.

[Q Xopa]

Originally Posted by a64pilot

It’s just a simple matter of scaling, nothing else.
Increase your battery discharge rate by a factor of ten, then if increase the bank size by ten and the charging capacity by ten, then of course you can do “it” whatever it is.

However it’s almost guaranteed that in order to increase the Charger capacity by enough is going to require you to run an engine, to drive either monster alternators or a generator.

Most choose to skip the huge, expensive battery bank and just run the generator.

Yes, you are right.

But it is getting closer to workable.

But when you say a 'simple case of scaling'. It might be a simple concept, but rarely easy to achieve in practise.

In the last few years the advances in efficiency in home split air conditioners has been quite remarkable.

Talking about scaling. The economy of scale and competition has had a remarkable impact on prices and efficiency. Capitaism eh.

SEERs have gone from 5 to 15 to 25 to 40 in only the last few years.

With the prices in LFPs similarly coming down this is getting pretty close.

[john61ct]

The point is, it is entirely do-able, no "technical" barriers at all.

Just questions of weight, space and cost.

But the question is, Why?

What does spending the many thousands of dollars more on the required infrastructure actually buy you?

Running your genset at a slightly different time of day compared to running the aircon? Probably not worth it.

Running your genset a few hours less? Maybe a bit greater value.

Now if your (required) ICE source is a set of massive alternators

and your boat usage pattern involves hours of motoring anyway every day

**maybe** it's worth a quiet cocktail hour inside the cooled cabin.

Or I suppose daysailors making use of overnight recharging off cheap shore power.

Full disclosure: I personally think aircon is **evil**, completely unsustainable in the first place.

But that's me, and I try not to let it color my laying out the decision factors.

[Q Xopa]

Yes, of course almost anything is doable throwing enough cash at it.

I dont think anyone was disputing if it is actually doable.

Size and weight wise, I dont you'd get off any better with a generator.

So I think the main issue we are discussing is cost.

My poor choice of words. Economically 'Viable' is more what I was meaning.

Its like the Solar panel market. It has recently got to such a scale the prices have come down so much that if current trends continue they will soon be as cheap as generator or even grid power.

As to the question of why. You might not want air conditioning but it would seem the global market is huge.

In the last 30 or so years it has become the 'norm' for cars, house etc. I'd assume boats must be similar.

But I actually agree that generally air cond is a massive extravegant waste of energy.

Having said that, I like the way efficency gains have been made recently.

The RV guys that are doing this are doing it with mostly Solar panels and usually Honda 2000 or similar for occasional backup.

Lots of people would rather use solar if adequate, than use a generator. I've heard many say they would like to make do without a gen. I can relate to this.

You sound like a fan of a generator. I have recently got one, but it is last on my recharge preference list.

But as said, different people want to do things different ways for different reasons.

[kas_1611]

The other answer is "can you live without the A/C?"

Windscoops on the hatches, shading over the boom and other methods can all reduce the ambient temperature in a boat dramatically. In the same way it is cooler sat under the bimini drinking your sundowner than it is sat in the sun.

Worth asking yourself the question and seriously thinking about it. Open hatches and a breeze are nature's air con after all.

[sailjumanji]

Honda 2000 or new model 2200 will make easy work of it. Plus backup if you run down batteries. We carry a 2200 as a spare, and it will power our 18k btu ac if we want. Otherwise everything is solar and battery driven with 800 watts of panels.