I have an Axpert 5Kva inverter hooked up to 4 x 100Ah batteries for  backup during load shedding. We are currently being shed twice a day for 2,5hrs and the inverter has started cutting out. When rebooting, batteries show at close to 50% which, I understand, is when the inverter cuts out anyway to protect the batteries. My question is, do I need to add a second battery bank or are the existing batteries just not getting enough time to fully recharge? The system is about 16 months old. Please help, any advice will be greatly appreciated 😊.

I think there isn't enough time to get the batteries back to 100% charged, that's the problem that needs addressing, the problem is that most Lead based batteries are specced at 10% or capacity for charging discharging so, if you take 50% out of the bank and re-charge at a rate of 10A (10%) it should take just over 5 hours to put the energy back into the bank, you should probably also check just before the next loadshed what the state of charge is reported as being, but unless you have more than 5 hours between rolling blackouts and your Axpert can charge at 10A, it should be able to, you're not going to get the battery back to a full state. But if you are starting with a full battery and you discharge 50% during a 2.5hour blackout, it would mean you are drawing more current from your bank than presumably the specs are suggesting you should, which would also indicate a shortened lifespan is to be expected...