I was looking at these batteries and considering whether to use a 12V battery or multiple 2V batteries for backup power. In any case, I came across this battery by Exide Tech - GNB Flooded Classic H1T - with a nominal capacity of 2504–4000 Ah, 20 year design life @ 25 °C. However, this is only sold in 2V cells. So is the case for the GNB FC NXT of capacity 621–2620 Ah. However, for the GNB FC MCT, they have a 192 Ah variant which comes in 4V.
This isn't an isolated case. The GNB FC TCXG with nominal capacity 50–280 Ah also only comes in 12V or 6V. Similarly, for the Absolyte GP (however, here they do mentioned that the 2V cells are paralleled).
Now this isn't for just 2V. As for the Absolyte GX 2000–6000 Ah Batteries, they are only given in 4V.
Now I understand that batteries that are rated in Ah are supposedly expected to provide low currents for a high amount of time. Wouldn't a higher voltage be preferred for that? I get that when you string 6 2V batteries together, you're essentially getting a 12V battery.