https://www.batterystuff.com/kb/tool...to-a-load.html
This web site has a simple calculator for sizing batteries to a specific amp load over time. While you may have a 240 amp hour capacity, remember that you only get to use 120 amp hours before you drain your battery down to 50% - as low as you want to routinely draw down to, if you do not want to kill your batteries. For a 36 amp draw for 8 hours down to 50%, the calculator says you need 750 amp hours of batteries. For a 28 amp draw over the same 8 hours it would be about 3/4 of that.
28-36 amp draw is a lot. My small Axis draws less than 20 Amps with the A/C and everything else except the microwave.
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