[Jack Houpe]

1200 amp hour could run a 12k btu inverter heat pump all night with no problem, on high with the unit compressor at max will draw about 9 amps @120vac or 90 amps at 12vdc per hour. Wattage is voltage x current so basically its 1080 watts if you have 1200 amp hour storage at 12vdc thats 14.4kwh which will run that ac unit for 13.3 hours BUT you can only use 80% of that 14.4kwh to keep your batteries safe so you can run the ac for almost 11 hours without damage to the batteries. Anything you add to the circuit will reduce that amount of time of course. 


You can build your own and save a fortune, I've built 3 sets of batteries and this one in my house for my solar generator is 30,720 watt hour and cost me about $3600, the only problem is waiting on them from China, the batteries are B stock batteries but the way I have them programed should last the rest of my life. The BMS's safeguard the system, all the little red wires looks tacky but its important to monitor LifeP04 batteries. You can configure them in series and parallel to make any voltage you want 12V 24V 48V. When we put solar on the roof of our rig I will change out my inverter to Growatt 3kw inverter charger all in one system just as I have in our house. These 2 units power the AC heat pump in our bedroom and the other does all the refrigeration in our house, if we ever loose electric we will have a cool or warm place to live and refrigeration for our food plus it saves us on our electric bill.