After 5.5 years, my 4x 100Ah AGM battery bank is performing like 60ah.
I won't replace them with another set of AGMs and here is why:
Cost of 4 new AGM batteries, 100Ah each, is about $760. But, to avoid discharging below 50% SoC, only 200Ah is usable. Over 5.5 years, that's a cost of $138...