Battery powered AC for my 33 ft boat

[Dave9111]

I'm doing some solar power at my house and I was messing about with some 12v, 100ah LIFEPO4 batteries and a 48 volt to 120 VAC inverter, 2500 watts.

I had a simple 5000 btu GE window air conditioner. I have realized that I can run the 5K btu AC full blast for about 10 1/2 hours off 4 - 12 v, 100 ah batteries via this inverter.

I have a canvas rig I made a few years ago to couple the AC unit to the top hatch behind the mast of my 33ft sailboat. It's easy to setup and take down. With 5K btus, it will effectively cool off the entire boat on a hot summer day. So it has enough capacity.

I also have a 48 volt charger that is a homebuilt assembly that looks like the "Chargeverter" sold by Signature Solar that can recharge this battery bank in 3-4 hours on 120 VAC shore power.

Since the boat really only needs to be cooled off initially at night to make it comfortable (I think?), I figure that one charge of the 4 batteries should last 2 to 3 or more days depending on heat and humidity. The AC units draws about 450 watts with the compressor running and maybe 100 watts when the compressor is not running.

It appears that a battery powered boat Air conditioning system may be practical while using more standard AC powered equipment without a generator. If I get to dock power every 3-4 days, I may be able to have some AC each night if its warm.

I am using a 2500 watt, 48 volt inverter which I got off Amazon. It starts and runs the AC unit just fine. While running the AC, the inverter fans don't even kick on . So the only thing that makes noise is the AC unit itself. The DC power consumption of the inverter when not running is very low. About 15 watts.

The idea of climbing into a cool boat to get some sleep after a hot summer day on the boat is very appealing.

Has anyone else thought about this and put this into practice?

Having a generator on a 33 ft sailboat is tight and noisy.

If this works as planned I wonder if I can rig a small mini split to cool off the boat. Or adapt the window AC to work in the cockpit locker?

Dave

[OldManMirage]

I have something similar to you, a 5K window unit that I have built a "frame" for that allows it to sit where the bottom 2 hatch boards would. I run it off my 1000W inverter and I have 400AH of Lithiums too. It works great, cools the boat right down.

I plan to use it now and then at the end of a day, after I have a shower. Dry out and cool down the cabin. Just for a couple of hours, not all night.

A mini-split is definitely more efficient. More expensive too. And figuring out where and how to mount the components can be tough. But it's certainly possible.

[Rohan]

I think you are basically on the right track. You might consider getting a very small portable generator - it may not be strong enough to start your A/C, but instead use it to recharge your batteries simultaneously while you drain them with the A/C. That will give you more running time when you need it.

Another option is simply an air conditioner that uses less power, like this one:

https://www.cruisersforum.com/forums...er-251683.html

I have been using this, but it's only strong enough for 1 cabin, it won't cool down the whole boat. If you do that, I recommend getting a 12v adapter and using your batteries, not theirs, because you would have to keep swapping out theirs every 3 hours and they can't be recharged while they are being used.

[Boatguy30]

I did work on a Turkish charter boat that had taken the condenser from a mini split and put it in a bucket sealed up with tar or sealant. They then piped sea water thru it. Unsure how long would last. A Honda eu1000 will run a 12k split unit.