A/C that runs off a battery...

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OverEasy
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Re: A/C that runs off a battery...

Post by OverEasy » Fri Jun 25, 2021 11:07 pm

Thanks for the clarifications JimmyT!

8) 8) 🐩

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Re: A/C that runs off a battery...

Post by Inquisitor » Sat Jun 26, 2021 1:34 am

Jimmyt wrote:
Fri Jun 25, 2021 3:24 pm
...
The stuff will work somewhat over a pretty wide range. However, if you want to spend a boat buck on a build, you'll want to do better.

I say go for it! And have fun.

Here is some light reading that may give further insight into your project, but remember this is a document for pros that have to make it right for a customer. You don't have to be so serious.
https://www.secop.com/fileadmin/user_up ... 20c102.pdf
Jimmy has me pretty well figured out... its all about the fun of the project / learning / another tool in the quiver. 8) :wink:
OverEasy wrote:
Fri Jun 25, 2021 5:47 pm
... but don’t you want to get a good vacuum pump to out-gas all the water/water-vapor that will inevitably sneak in. Can’t the water content freeze and potentially cause a blockage?
Good reminder / clarification... The O.P. video series is a great basic tutorial. Here is where he talks about evacuating / vacuum testing - https://www.youtube.com/watch?v=HJpQn2gL0Aw&t=1540s

I started looking at vacuum pump / gauge sets and justifying it in my head for (1) this project (2) in case my house/car units ever need working on (3) besides... I can use it for resin-infusion for fiber-glassing projects.
Jimmyt wrote:
Fri Jun 25, 2021 8:46 pm
... It is not as good as a pressure test in my book, but it's quick and convenient (and exactly what I would do unless the system has a large charge).
Hadn't thought about this, but makes total sense... vacuum test is only going to do a 14 psi differential, pressure testing at the hundreds of psi of at-least the working pressure would be a more thorough test. Hmmm! Do they make a budget (Amazon $100-$200) vacuum pump / gauge set that can use the output side as a pressure loading test??
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Jimmyt
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Re: A/C that runs off a battery...

Post by Jimmyt » Sat Jun 26, 2021 4:54 am

Taking a page out of Bilgemaster's playbook, the "freight" has a budget 134a set.
https://www.harborfreight.com/ac-r134a- ... 60806.html

Since 410a and 134a use the same type oil, it's probably ok to use the same gauge set on both. If you aren't working on systems with compatible oils, don't use the same gauge set.

Since 410a works at much higher pressures, you'll need to find a gauge set that is set up for 410a. There are a lot of gauge sets for 134a floating around that may not work for 410a. Just check the gauge range before you buy.

Also, you'll want to buy access ports that are compatible with your gauge set.

I've used budget gauges, and some are ok, but I have a real vacuum pump, so don't know about the budget pumps. Maybe someone can recommend a budget pump.

Pressure testing is done with dry nitrogen. Here is a cute article on pressure testing by a kindred spirit...

https://www.hagerty.com/media/opinion/f ... e-testing/
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Re: A/C that runs off a battery...

Post by Inquisitor » Sat Jun 26, 2021 7:40 am

Jimmyt wrote:
Sat Jun 26, 2021 4:54 am
Taking a page out of Bilgemaster's playbook, the "freight" has a budget 134a set.
https://www.harborfreight.com/ac-r134a- ... 60806.html

Since 410a and 134a use the same type oil, it's probably ok to use the same gauge set on both. If you aren't working on systems with compatible oils, don't use the same gauge set.

Since 410a works at much higher pressures, you'll need to find a gauge set that is set up for 410a. There are a lot of gauge sets for 134a floating around that may not work for 410a. Just check the gauge range before you buy.

Also, you'll want to buy access ports that are compatible with your gauge set.

I've used budget gauges, and some are ok, but I have a real vacuum pump, so don't know about the budget pumps. Maybe someone can recommend a budget pump.

Pressure testing is done with dry nitrogen. Here is a cute article on pressure testing by a kindred spirit...

https://www.hagerty.com/media/opinion/f ... e-testing/
Too funny! :? I hadn't even considered anything besides the 134a. Long ago you had said 134a was the most readily available, lower pressures and tolerant of Noob's. I filed that as the end of discussion / gospel / written in stone. I moved on to the next learning curve. I was all laser focused for 134a equipment. Then I mentioned one little phrase, I wanted to be able to work on a house system as justification for the purchase. You listen to me better than I listen to me! :P :D

I'm now... seeing that fluorocarbon choice doesn't seem to be fixed for any one device type. I had three large, "professionally" installed central heat pump units in the Atlanta house and had nothing but routine trouble with them. And when it dipped much below the 32F, the electric heating elements fired up. I once measured the electricity draw being 10x when they were on versus just the heat pump! One Christmas when we had the house filled with guests and all units running... $800 heating bill! OUCH!

Here in our little retirement home, I installed one mini-split myself five years ago. It has no electric back-up and it has worked just fine pumping out heat even in single digit outside temperatures. I'm a convert! Mine says it uses 410a and the Internet says, these mostly use 410a, but exceptions exist.

Because of the higher pressures, I should consider 410a first and just get adapters for the 134a??? Looking at 410a/134a options on Amazon seemed to narrow the field quickly. Most were geared for the 134a only. I found this one https://www.amazon.com/gp/product/B079JJSFQW. Says it'll do both 410a/134a and goes down to 150 microns (20 Pa / 0.003 psi). How does this compare to your real professional vacuum pump?

Pressure testing - Good read and exactly what I'm talking about. No dealer mechanic has the time to do that thorough of a job. So you end up back at the dealer or having another service technician come out to do the house. I'd just as soon have that diagnostic ability in my own tool bag. And I just happen to have a CO2 cylinder for MIGing 8)

Aside - One of Dad's favorite cars was a BMW 2002.
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Jimmyt
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Re: A/C that runs off a battery...

Post by Jimmyt » Sat Jun 26, 2021 11:26 am

Check the last bullet. Vehicles with 134a have a handy quick-coupler system for connecting your gauge set. This set you're looking at doesn't have the 134a couplers. You can get them as add-ons, but you'll need them for vehicle work. On your backyard ac build, you can put whatever access ports you want.

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Re: A/C that runs off a battery...

Post by adudinsk » Mon Sep 13, 2021 4:26 am

Just got a new member at the club with a 26D. His wife has difficulty breathing, so he NEEDED an a/c unit that can run all the time.
He installed 8000w of solar.. yup.. 8000w, and Li-Ion batteries ( 2 x 360AH ).

He has no problem running the A/C all day/night.. and cooking on his hot plate if needed (usually uses a butane stove.. or his BBQ)

He did mention something about the extra weight almost sank him.. but since then offloaded much of the "non-essentials", and I think installed a few bilge pumps.


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Re: A/C that runs off a battery...

Post by Tomfoolery » Mon Sep 13, 2021 5:08 am

I think you mean 800W, not 8000W. A typical flexible 100W solar panel is about 7.3 ft^2, and it would take 80 of them to make 8kW. That's 587 ft^2, and if the boat was a 26 ft x 8 ft rectangle, it would only hold 208 ft^2 of panels, with nothing else whatsoever on the deck or cockpit.
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Re: A/C that runs off a battery...

Post by Jimmyt » Mon Sep 13, 2021 5:19 am

+1 And rigid panels would require around 450 sf. You wouldn't really need that much to cool a Mac. But, I'm very interested to see what his setup is. Maybe you can get an on-board tour and photo session! :wink:

If he really has 8kw of solar on a 26d, I'm dying to know the details. Nothing is impossible - but some things are really difficult.

Here is a home kit that will do 8kw, for reference. https://www.gogreensolar.com/products/8 ... e-inverter
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Re: A/C that runs off a battery...

Post by Russ » Mon Sep 13, 2021 6:06 am

Sumner's 26D is probably the most solar Mac in the world with quite the clever fabrication.

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Re: A/C that runs off a battery...

Post by Tomfoolery » Mon Sep 13, 2021 8:44 am

Jimmyt wrote:
Mon Sep 13, 2021 5:19 am
If he really has 8kw of solar on a 26d, I'm dying to know the details. Nothing is impossible - but some things are really difficult.
But the maximum solar irradiance at the earth's surface is around 1kW/m^2 under ideal conditions, or about 92W/ft^2. Solar panels are only about 20% efficient or so, so that's 200W/m^2 [18.4W/ft^2]. It would take something like 21 ft x 21 ft of panels to actually output 8kW.

My 300W of solar on top of my van has only ever gotten to 15A at 13.4V, according to the charge controller, which is a shade over 200W. They will keep my fridge/freezer (compressor, not ammonia absorption) in my van running indefinitely, as they put out 3 times what the compressor draws when it's running and therefore charges the battery even when running, but the air conditioner on the roof draws about 150A DC through the inverter when the compressor runs, so those panels don't even make a dent in the draw from the 600Ah lithium battery under the best conditions.
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Re: A/C that runs off a battery...

Post by Jimmyt » Mon Sep 13, 2021 4:50 pm

Tomfoolery wrote:
Mon Sep 13, 2021 8:44 am
But the maximum solar irradiance at the earth's surface is around 1kW/m^2 under ideal conditions, or about 92W/ft^2. Solar panels are only about 20% efficient or so, so that's 200W/m^2 [18.4W/ft^2]. It would take something like 21 ft x 21 ft of panels to actually output 8kW.

My 300W of solar on top of my van has only ever gotten to 15A at 13.4V, according to the charge controller, which is a shade over 200W. They will keep my fridge/freezer (compressor, not ammonia absorption) in my van running indefinitely, as they put out 3 times what the compressor draws when it's running and therefore charges the battery even when running, but the air conditioner on the roof draws about 150A DC through the inverter when the compressor runs, so those panels don't even make a dent in the draw from the 600Ah lithium battery under the best conditions.
Now you're going to screw the whole conversation up by talking real world performance instead of BS marketing ratings... :D

For 8kw on a Mac, I'm envisioning something that looks like a Jon boat with a billboard laid flat atop her... But, I try not to call BS until I know exactly what someone is telling me (perspective is sometimes a help, and sometimes a hindrance). After all, I don't know everything.

To clarify, I agree with you. :D The numbers don't appear to work for a usable AC system for an entire Mac (while maintaining the ability to still be a usable boat). :wink: I don't think you'll need 8 kw to do it. It would probably run on less than 1kw but could need quite a bit more to start the compressor. With a kickstart kit, you can get that down some, but it's going to take a lot of panels, (and a lot of battery) to keep a Mac ac'd 24/7 with no shore power. Then, you've got to deal with inverter inefficiency to get to the real battery numbers for a full night's cooling. After you've gotten that, you can start thinking solar panel sizing (including all of the inefficiencies, insolation at your location, etc that impact the required panel capacity).
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Re: A/C that runs off a battery...

Post by adudinsk » Wed Sep 15, 2021 4:25 am

The owner clamed 8000w.
NOT 800w , I asked.. but who knows .. maybe he got it wrong.

The boat has WAY more panels than the one in the photo.

Maybe the owner is incorrect.. but he kept touting 8000w at the club.
Said it cost over 12Kus for just the first set of panels.. then he kept adding
(overkill for a 8-9k $ boat IMHO)

I will look at the panels when we pull out.. and count them up.. see if its actually 800W.. not 8000W like he said.

For his batteries, I know he uses a 30A AC charger when at dock.
And has an inverter the size of a microware.
Runs his AC all day/night on solar only... also cooks off his electric cook top if needed.

His first trip he said he almost sunk with all the weight.
(I guess he miscalculated something...lol)

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Re: A/C that runs off a battery...

Post by adudinsk » Wed Sep 15, 2021 4:26 am

And yeah.. the boat is mostly solar panels..

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Re: A/C that runs off a battery...

Post by Jimmyt » Wed Sep 15, 2021 4:32 am

adudinsk wrote:
Wed Sep 15, 2021 4:26 am
And yeah.. the boat is mostly solar panels..
If you get the opportunity, please take a pic. I'd love to see it.
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Re: A/C that runs off a battery...

Post by OverEasy » Wed Sep 15, 2021 10:44 am

And I thought the 100 watt four panel amorphous solar cell 4 panel kit from Harbor Freight was big enough…..but 8000watts! 😳 I could weld with that!!!

Never mind run a 1500 watt A/C, a 1500 watt induction cooktop, a 1500 watt resistance heater and still have 3500 watts to run a Mig welder!!!

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