Powering Air Condition

[lmannyr]

I'm in the middle of restoring my boat (see signature). I'm at a point to start thinking about A/C placement and how it will be powered. Cool Mate is what may work for my 23 footer with aft cabin. The 5000 BTU unit goes for about 2k and a 10,000 BTU unit goes for 500 bucks more.

Full load amps at 115 volts:

5,000 BTU unit = 3.1
10,000 BTU unit = 8.6

Problem is the generator... THERE FREAKING EXPENSIVE!!! ABOUT 4K AND UP!!!!

Unless there is a MUCH cheaper ($1K cost) MARINE generator that I can place in the engine bay (without blowing up my boat), then batteries will have to do. The A/C is a must for the family or I boat alone.

Given the above info, how many batteries to power just the AC for say...6 hours. What size batteries? What gauge cables from battery location in engine bay to A/C location in cabin?

Yes, I'll need an inverter. Which will be nice to have to top off batteries before and after trips with shore power.

 

[tashasdaddy]

Re: Powering Air Condition

i think you need to look at 12 volt AC units. google Marine aircontitioner. "http://www.dcbreeze.com/index.html"

 

[lmannyr]

Re: Powering Air Condition

i think you need to look at 12 volt AC units. google Marine aircontitioner. "http://www.dcbreeze.com/index.html"

DC Breeze
576 Watts. (48 amps X 12 Volts) 5,000 BTU

The Cool Mates:
356.5 Watts (3.1 Amps X 115 Volts) for 5,000 BTU
989 Watts (8.6 Amps X 115 Volts) for 10,000 BTU

----These are MAX Watts.

This battery bank will also power a Fridge (not sure wattage yet), LCD TV, DVD, Radio, and occasionally the single burner.

Sounds like alot of batteries.

According to this page, at 400 watts continuously, a 1 225 amp hour battery ($350) will run the AC for 6.75 Hours. Thats discharging the battery to 50% capacity.

How can I get the engine alternator to charge the batteries while on? How will this affect the inverter/charger? Will current run the wrong way?

 

[tashasdaddy]

Re: Powering Air Condition

trying to run all that, you need a genset. bite the bullet.

 

[mspring]

Re: Powering Air Condition

One of my next projects will be a houseboat so I have been wondering about powering an ac unit also. I will not have room for a generator plus I dont want to hear a lot of noise. I am leaning more toward battery power and several people have told me solar panels on the top will charge some. Havent really researched it yet. Good post I am looking forward to see what everyone says.

 

[Caveman Charlie]

Re: Powering Air Condition

In the old days they used to use something called evaporators to help cool spaces. They may not work well in muggy Florida and out over the water. But, I thought I'd throw it out there as a possible way to take some load of the AC so that it can run longer on less electricity. After all the boat is surrounded by cool water. To bad a person can't make use of that somehow.

Also might be good to well insulate your cabin and seal up any air leaks to the outside.

 

[txmntman]

Re: Powering Air Condition

just another thought. Some folks are believing that if it goes on a boat, it MUST have marine on it somewhere. So, I'll offer an alternative. Check out the Honda eu2000 generator. It is portable, and weighs about 45 lbs, and you can hold a conversation while straddling it. I know a guy from SC that uses one on his 18 ft walkaround with an A/C he bought from wally world. No, it's not marine, but he built a frame for it and has used it for 4 years. He straps the generator to the stern and powers the 120 A/C with it. He uses a RV septic hose to route the air into the cabin, and has A/C....
The generator is about $1k, and the A/c was about $150. At that price, if the A/C goes out, replace it...

 

[lmannyr]

Re: Powering Air Condition

Thanks for the info. I'll be sure to look at the portable systems. Efficiency will be a huge factor on which design I will go with. The less watts the better.
Size will also be a factor. If it's portable, and it takes a dump, it will need to fit through the cabin entrance (preferably with the door on) to replace.

It's definitely nice ($$$ wise), the portable units are in the 300 dollar range as opposed to 1k+ with marine units. It will be easier to design the cabin around a portable system too. I'll just build an open closet that it can slip into.

I also like how compact the unit is!! It's smaller than I thought! Weighs only 49 pounds! Thats also lighter than my 300+ pounds of high amp/hour batteries.

Given the cost of the batteries and inverter, the Honda EU2000 wins. The Honda also wins saving me 250+ pounds.

The Honda even has DC output. Nice way to charge the engine batteries while anchored/docked/beached and listening to the radio or whatever.

I'll need to search at the portable AC's though. Not too sure about those yet. I'm looking for small, compact, efficient, with hopefully 10,000 btu.

THANKS for saving me the battery/inverter installation headache!!.

 

[Robj]

Re: Powering Air Condition

I just looked at the air conditioners in my West Marine catalog. One thing that is different from your home air conditioners is the marine version uses sea water to cool the condensor which would make the unit more efficient than one that is cooled by air. But the marine versions are Expensive.

Have a great day,

Rob.

 

[jlinder]

Re: Powering Air Condition

DC Breeze
576 Watts. (48 amps X 12 Volts) 5,000 BTU

The Cool Mates:
356.5 Watts (3.1 Amps X 115 Volts) for 5,000 BTU
989 Watts (8.6 Amps X 115 Volts) for 10,000 BTU

----These are MAX Watts.

This battery bank will also power a Fridge (not sure wattage yet), LCD TV, DVD, Radio, and occasionally the single burner.

Sounds like alot of batteries.

According to this page, at 400 watts continuously, a 1 225 amp hour battery ($350) will run the AC for 6.75 Hours. Thats discharging the battery to 50% capacity.

How can I get the engine alternator to charge the batteries while on? How will this affect the inverter/charger? Will current run the wrong way?

I ran the same calculations on that page and got 2.835 hours. Also you are talking about more than 400 watts (from above)

If you want to draw 48 amps for 6 hours you are talking about 288 amp hours. With 50% capacity you are talking about a 576 amp hour system.

You mention powering a burner. Do you mean an electric hot plate? If so they take a huge amount of power.

 

[lmannyr]

Re: Powering Air Condition

I ran the same calculations on that page and got 2.835 hours. Also you are talking about more than 400 watts (from above)

If you want to draw 48 amps for 6 hours you are talking about 288 amp hours. With 50% capacity you are talking about a 576 amp hour system.

You mention powering a burner. Do you mean an electric hot plate? If so they take a huge amount of power.

Yes your right. I did not account for the 50% discharge recommendation. It 4 225 amp/hour batteries = 1000 amp/hour battery bank. At $350 a battery, thats $1,400.00. Thats a lot of money for batteries that may need to be replaced every few years.

For the price of the batteries above, I would rather get the Honda EU2000 for $1,000.00 (less if purchased used), a 10,000 BTU portable a/c and have change left over. Lets not talk about the cost of an inverter for a 2000+ watt system.

When I'm not using the boat, I could use the generator elsewhere (during huricanes, my wife's business, etc...).