Question about deep cycle/ marine batteries.?

Question

I am interested in finding out the ablility of deep cycle or marine batteries to power an air conditioner. Looking at a 5050btu window unit (115 volts, 4.7 amps, total of 540.5 watts [surge wasent listed]). I know that marine batteries are different from deep cycle, but not sure how. Any reccomendations on what i would use and how many I would need to run it for 6-8 hours, and what kind of inverter and charging system would be required. Please be as detailed as possible and dont answer if you arent sure. thanks

this actually isnt for a boat, but i posted it here because i know this is where people with experience in these things look. a generator is not an option in my application

Answer 1

Any of the air conditioners that I have seen on boats are run while on shore power. Definitely an inverter needed. We have friends with a trawler that have 12 house batteries(deep cycle) under the deck to run electronic equipment. Others with air conditioners run a generator. I do not know how you can run an air conditioner for 6 to 8 hours on batteries.

Answer 2

marine batteries / deep cycle means they are optimized for delivering low current ;levels over along time, as opposed to starting batteries that need to give a large burst of power to turn over an engine.

Batteries are listed in terms of "amp hours"; ie 500 amp hour battery will give 1 amp over 500 hours, or 500x 12v = 6,000 watts.

HOWEVER! the amp hour listing is a little disingenuous, as the power available drops off rapidly as battery draws down...a charged battery at 13.4 volts will hum along; when it gets to 12 volts it does OK, under 12 volts it still has power to give but not much.....if you were running a light, you'd have first bright, then adequate and then a dull glow.

A/Cs as you mentioned have asurge every time they start; if you're running an inverter I'd get at least a 1000 watt job.

As power available drops, your A/C will have to work much harder; I doubt that, even though on paper you have 12 hours capacity in a 500 amp hour battery, that you'd get more than 8 hours out of a system.
You'll need at least a 10 amp charger to keep up with the load.

Many marine and many R/V or truck supply stores sell 12v A/C units.......consider doing that rather than running thru an inverter and losing 15% to resistance in this extra step....you can also look at the draw in 12v on the data plate and know exactly ow much is going out and how much is going in.........

Answer 3

I think this is your answer I bought a system to power a tv and vcr combo for my camp. The dealer sent two 84 watt panels a inverter and charger plus 4-12 volt deep cycle batteries although he suggested I buy two more. The four I got was the minimum required. The camp however was sold before I could install so if you want it you can have the lot for 2,500 bucks never even got out of the boxes.

Answer 4

get yourself a generator and save yourself a whole heap of money. Honda sell a portable 1 - 3 kva generators that are that quite and very fuel efficient

if mounted on deck on rubber mounts you wouldnt hear it over your air con.

Build a waterproof enclosure for it with soundproofing foam etc you wont hear it if sitting on top of it

You can then run other appliances off it as well including battery charger. the bigger you go the more power you can draw.

the amount of battery power to run a aircon for 6-8 hrs is huge, more space and weight than a small generator.

Marine batteries have higher cranking amps than normal deep cycle batteries otherwise similar

Answer 5

Too many batteries, you'll need a generator, it's probably cheaper than the amt. of batteries you will need, Honda makes TINY generators now.