I have a quattro 48/8000. There are 24 lead acid 910ah batteries connected and after 6 years they are looking a bit tired. When the sun goes down they are at 100% but by morning that is 70-80%. Sounds fine? But the voltage makes it unusable. If I try to make breakfast before the sun comes up, the voltage drops to below 44 and alarms go off. Looking at the book, the minimum voltage is 38. Can it go below that? I'm just trying to delay the big spend on lithium. I'm thinking of starting with 6 pylontech us2000s, but that is going to cost me 6000€+. The lead acid batteries cost me 8000€ just 6 years ago.