Last summer I replace my 1600BTU Mermaid and a Mase 4.0 generator with the Mabru 1200 BTU unit and 2 Iron Phosphate 12V/250AH batteries.
Results: I am VERY HAPPY ! No more noisy generator, smaller AC unit cooling better than the Mermaid. I can get 10 hrs with the batteries. Customer service: A+