cliff_m_b

I am currently investigating doing something similar but to a R/V with a roof top mounted a/c unit. I was told by me r/v dealer to look at golf cart batteries because of their deep cycle and ability to hold a lot of energy. I believe the current load of a 110 a/c at 30 amps would require 3 golf cart batteries for a full 8 hours use before recharing would be required.

apollard

Golf cart batteries are 6 volt, so you would need 6, not 3 (assuming a 12 volt converter).

However, 110 volts at 30 amps is 3300 watts. An inverter running at this load will pull in excess of 200 amps at 12V - you won't run that for long off even golf cart batts. Even a six battery bank will be good for a couple of hours at most.

Uncle Dave

Wouldn't it be 300 amps?

When my outback inverter is putting 90 amps into the 12V bank its only hitting the 120V circuit for 9 amps.

Uncle Dave

pstorti

iTrader: (2)

I had a 5200 btu Mermaid Marine unit in my 28 Daytona (mentioned above), had 2 group 24 batteries, and 2 group 27 batteries, a 1750w cheap Xantrex inverter I bought at Costco and the thing worked perfectly. It would freeze you out of the cabin if you left it on long enough, I ran it off all 4 batteries (Cabelas AGM) and it would run all night and I would be in the mid 11's in the morning for voltage. I think your idea will work fine but you will probably need at least 2 group 31 batteries, if the are only powering the AC its not the end of the world if they get run down. You just have to try it out and see what you need. The power usage will also be affected by cooling water temp, ambient temp and thermostat setting. Remember once the cabin is cooled the compressor will cycle on and off to maintain the temp so you don't have the full load the entire time. I left my fan ON all the time so it wouldn't wake me up when the system cycled on and off.