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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.

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  • \$\begingroup\$ Note: Other companies like Narada ( en.naradapower.com/index.php/applications/info/8?ctype=72 ) and Fiamm ( fiamm.com/fileadmin//user_upload/SLA_FOLDER_NA_ENG.pdf ) follow this while some, like Yuasa ( gs-yuasa.com/en/products/pdf/NP_Series.pdf ), don't. \$\endgroup\$ – user5740623 Aug 22 at 7:45
  • \$\begingroup\$ Does the weight of the cells give you a clue? (I haven't checked.) They have to be lifted into place. \$\endgroup\$ – Transistor Aug 22 at 7:48
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    \$\begingroup\$ @Transistor Using one of the exide ones as reference: the 4V-192Ah weighs 106 lbs while the 2V-480Ah weighs about 109lbs. The lower rated 2V batteries weigh lesser as well. When looking at the Sonnenschein A500, the 2V-10Ah battery weighs 0.7kg while the 12V-10Ah battery weighs 4kg. So it is possible that weight is one of the considerations. Is that enough to overcome the extra cost of a multiple-2V battery system, while having a higher current. \$\endgroup\$ – user5740623 Aug 22 at 8:00
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They are sold by the cell.

You assemble cells into batteries.

Common word usage in English has blurred the distinction between "cell" and "battery."

A cell is the smallest construction capable of generating voltage. That voltage is dictated by the chemistry.

A battery is a bunch of cells in series used to generate a voltage higher than that of a single cell.

The cells you were looking at are intended to be used to build very large batteries.

You connect them in series to get the desired voltage, then in parallel to get the desired current and redundancy.

You can then replace individual cells that go bad instead of replacing a larger battery.

Another, final point to consider is weight.

The cells you were looking at weigh over 400 pounds (over 200kg for you metric types.) Easier to work with individual cells than a battery that would weigh over a ton.

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Do you realize that if you want to get battery with higher voltage, you have to connect cells in series?
When you connect cells in series the capacity [Ah] does NOT add up, you still have the same Ah as a single cell.

So you can take several cells (let's say 6 pieces) with capacity say 2Ah each and connect them in series, yes you will have battery with higher voltage (6x2V=12V), but with the same capacity 2Ah. When you connect them in parallel, you will have battery with voltage 2V and capacity will be 6x2Ah=12Ah. With the same amount of cells you can choose whether you want 12V 2Ah battery or 2V 12Ah battery. It is a trade off.

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