Potential Cabin A/C Solution

[Yakmandu]

Found this future air conditioning solution on Kickstarter. It will cool 55 square feet and runs on battery power. It might be a great solution for a C-Dory cabin if it makes it to market.

While the specs show a 24 volt power connector, there will be a 12 volt power connector available.

I have no connection to the product or campaign, just watching it closely. I haven’t seen another product that is taylored to a small cabin and runs on battery.

https://www.kickstarter.com/project...able-multifunctional-air-conditio/description

 

[ssobol]

1700 Btu is not a lot. A C-Dory is not well insulated.

My 5000 Btu AC unit can take awhile to cool down the cabin and can struggle on hot sunny days if the boat is in the sun.

My 5000 Btu unit was $100. This new one is ~$500 (list price) for much less cooling capacity.

However, the device shown seems to be a real AC unit as opposed to some of the other small battery powered "AC" units that are really just small evaporative (swamp) coolers.

 

[robhwa]

It will cool 55 square feet and runs on battery power. It might be a great solution for a C-Dory cabin if it makes it to market.

"Cooling" 55 square feet doesn't really mean anything. Some of the most powerful air conditioners available are those in cars, often >10,000 BTU, because the hot air moving across the windows transfers heat into the car very efficiently and sun shining through the windows adds to the problem.

I had a relatively small motorhome (a Rialta). The rooftop AC was 15,000 BTU.

Going the other way, my Wallas stove puts out 3000-6500 BTU. It heats the C-Dory OK, but works much better in my 4Wheel pop-up camper, which is insulated, even though the "cabin" is much larger.

If you insulate the windows (maybe insulated curtains, and use this device at night, it might help you sleep when you are on the hook...not running a portable generator is a plus, for sure, but after 5 hours how do you charge the batteries...how many Amp hours did you drain. They really need some math on the site, SEER, wattage, etc., before this thing can really be evaluated.

 

[Foggy]

On a hot night, I keep cool with a moist washcloth on my forehead.

Aye.

 

[BillE]

The "Ultrasonic Mosquito Repellent" feature, along with the photos of using this AC outside, tell me that this is yet another snake oil company.

 

[robhwa]

If you truly want to air condition your C-Dory on a hot day, you'll likely need at least 4-5000 BTU, and that might not work on a really hot day, but it would certainly help.

The best way to get the efficiency required to run off of batteries, or an engine when it is running, might be to transfer heat from your cabin into cooler ocean or lake water. Puget Sound is almost always cold, (i.e. Tacoma WA 46-55) but Florida can be hot (Cedar Key FL 66-88), so such a system might not work well in Florida some of the time.

Geothermal systems are much more efficient than air to air systems. You basically transfer heat into water anyway, which has limitless supply from a boat.

Here is such a unit made for marine use.

https://www.coastalclimatecontrol.com/i ... y=25823699

4200 BTU should help a lot, and 35 Amps is about what a newer Honda 90 advertises out of the motor. An Evinrude E-Tec 115 advertises 50 amps output.

Equally attractive would be the dual system so you could turn off your Wallas stove when you are motoring and heat the cabin without using up your diesel fuel.

As to batteries, four 100 AH (maybe Group 31) batteries in series would give you about 6 hours full-tilt for the AC and starting from fully-charged to half, and would weigh about 300 lbs. A bonus would be I could run my trolling motor twice as long as I can now.

You shouldn't drain regular batteries more than 50% or so regularly. Perhaps the Lithium batteries that Bob Austin is checking out will be a system that can handle these loads? Lithium will be lighter for the AH and can be drained regularly much lower than Pb-based batteries without damage, supposedly.

If you drained 200 AH from the batteries during a night, you'd still need to figure out a way to charge those batteries during the day. The Evinrude would shine there at 50 Amps.

To be practical, you'd probably need 2-3 nights, thus doubling or tripling the batteries...not practical.

My 2003 Honda 90 seems to put out about 20 amps when I test it, so no go for me. Newer ones claim 35 amps but I'm always a skeptic.

I supposed that when I'm in Florida or lower Alabama I'll still be using a generator and cheap air conditioner.

 

[ssobol]

If you truly want to air condition your C-Dory on a hot day, you'll likely need at least 4-5000 BTU, and that might not work on a really hot day, but it would certainly help.

The best way to get the efficiency required to run off of batteries, or an engine when it is running, might be to transfer heat from your cabin into cooler ocean or lake water. Puget Sound is almost always cold, (i.e. Tacoma WA 46-55) but Florida can be hot (Cedar Key FL 66-88), so such a system might not work well in Florida some of the time.

Geothermal systems are much more efficient than air to air systems. You basically transfer heat into water anyway, which has limitless supply from a boat.

Here is such a unit made for marine use.

https://www.coastalclimatecontrol.com/i ... y=25823699

...

A big advantage (IMO) to the window type AC is that it can be run even if the boat is not in the water. I run my AC with the boat on the trailer more than when the boat is floating. Like when it is parked in front of my house and I am working on it.

 

[thataway]

I have used 5000 BTU air conditioners (window type) on two 22's and 2 25's, and a 9200 BTU on the Tom Cat. By using Reflextic (bubble wrap with silver mylar coating) in the windows and hatches, you can lower the internal temp in the C Dory 25 by 15 to 20* from ambient--this is enough to get a good sleep at night--and tolerable working in 95 to 100* conditions during the day.

1700 BTU would not even cool the bunk area adequately--unless really sealed off.

The LiFePO4 batteries may handle the loads, but at about $950 a for 100 amp hours usable, they are going to be pretty expensive. There is some inverter loss. Also there is a caveat that you are limited in amperage draw for a single battery to 20 amps continuously--40 amps for two batteries, and 80 amps for 4 in parallel. The surge current of 200 amps is limited to 30 seconds.