But anyway – next time I wouldn’t buy AGMs any more, instead I’d go for cheaper and more sturdy deep cycle wet batteries. They need more attention (refilling and checking) and are dangerous if handled wrong (they release a gas when overloaded, which can lead to an explosion), but on the other hand and if treated not too bad, they do 1200 cycles+ (80% discharge), while the AGMs we own are rated at around 250 cycles at around 80% discharge (We are at around 500 now… ), while being approx 1/3 cheaper for the same Amp rating.
The downside of wet deep cycle batteries is, that their ratings for fast discharges are not as good (so for example applications with strong inverters, like our 1500 Watt unit) – that’s the price you pay for the thicker lead plates. To compensate that, more paralleled batteries would be needed. On the other hand I get 4 wet deep cyclers + I have some change left, for the price of 3 AGMs. And four wet deep cyclers should be able to keep up with the power drain of the inverter, even when it hits it at 1500 Watts/220 volts, which is 1500/220*12 = 81 Amps, or around 20 AMPs per battery. Speaking from 120 AMP wet deep cycle batteries and most data sheets I have seen of those, which are quite similar.