I realised that most inverter batteries like car batteries are not of high quality. I would like to recommend this brand of turkey batteries, they deliver longer hours and will last for more years. One of mine is over 3years, still running 800va luminous, however you can only use them with an inverter with battery type selection like prag, or a and e dunamis, prag I would recommend. 210amps mutlu batteries should be like 135k for one ..
Contact me for more info 08055312883
Or Amos 08054511269 to buy. The picture is my set up, prag with mutlu batteries I get 12 hours of use and above 50percent discharge