12v Rooftop RV style Air Conditioning

[IronZebra]

I have the Atlas Acadia 25 (downeast style boat) and am considering putting a RV style A/C on the roof. I have zip in curtains that enclose the piloting area and a door off the piloting area to the V birth and head. So not a big space to cool.

Initially was thinking a AC powered unit that I could use at marina or with generator on the swim step at anchor. But it sure would be nice to run it while driving as well. I was looking on Amazon and out of curiosity did a search for a 12v RV style unit. It appears that they now have these. They are shipped from overseas with no refrigerant and will operate on 12 or 24v. The one I am looking at says will need an alternator that puts out at least 75amp and cools between 8750-13500btu.

Wondering if anyone has experience with these. Also what other things I might need to consider that I am not thinking about.

 

[DavidM]

I think I found the A/C you are considering on Amazon: https://www.amazon.com/Universal-co...lja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1

It is rated at 2,200 watts of cooling which is 7,500 btu/hr and uses 850 watts at 12V or 70 amps. Its efficiency is rather low even for RV units.

I used to have a similar boat to yours, the Pompano 23 and I understand the area that needs to be cooled. This one should do it at least in moderate, under 90 F climates, but that canvas/stratiglas enclosure has little insulating value. It would probably be better to mount it so it blows into the forward cabin so you can close off the companion way when you are sleeping.

But..... It all depends on how much battery capacity you have and how much alternator capacity you have for recharging. The Yanmar 110 ho engine probably comes with a Hitachi 60A alternator or at best 80A. That won't do. You will have to upgrade it to a high output alternator with an external regulator that can supply more amperage continuously.

Then you will need about 400 amp hours of lithium batteries to supply enough power to run the A/C overnight. And you will probably have to run your propulsion engine for at least 4 hours to recharge the lithium battery bank.

When you get all that installed, you will have about $5,000 in the A/C, alternator and regulator and the lithium batteries.

Is that worth it?

David