Battery Bank Question

Okay, I've calculated my load needs, figured out my required watt-hours, and amp-hours. My amp-hours came out to 465 amp-hours. The online calculator recommended 3-strings at 155 amp hours which equals 465 amp hours. Sorry, if this is a dumb question, but for a 48-volt battery bank, how do I determine how many amp-hours each battery should have and how many I need? I wish to use 12-volt batteries wired in series, paralleled. Thanks in advance.

You have established a Wh required for your battery. You're almost finished.

Multiply it times two (to ensure you don't discharge below 50%)

Divide it by 48.

That's the # of Ah you need in the 48V bank. Each battery used in series must have at least that Ah. If you have two strings in parallel, they can be half that amount.

General formula:

(Wh * 2) / # batts / Batt V = Ah per battery.

If you need 10000Wh and want a 4S2P bank of 12V batteries:

10000 * 2 / 8 / 12 =208Ah each 12V battery

If you want 8S2P bank of 6V batteries:

10000 * 2 / 16 / 6 = 208Ah each (see how that works - I haven't changed the fact that there are two parallel strings, so Ah of each battery in a string doesn't change)

If you want 4S1P bank of 12V:

10000 * 2 / 4 / 12 = 417Ah each 12V battery

I am not a fan of multiple parallel batteries. I will always recommend a single string of the correct size rather than smaller paralleled batteries. I'd recommend this one at 568Ah. You'll need 12 of them for 48V.
I have the 8V version right now for one of my systems and I heartedly recommend it. I'm recommending the 4V version for you though because the 8V is just so damned heavy. Two adult men can barely get them into position.

One can always go to 2V

Love Rolls.

When Rolls explicitly allows parallel strings, and one engages in best practices, I don't think there's any risk in parallel strings, but it does make one big difference:

The fewer cells you have, the easier the battery is to maintain. In my 48V 4S2P setup, I have 48 cells to check. Sucks.

snoobler said:

One can always go to 2V

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snoobler said:

The fewer cells you have, the easier the battery is to maintain. In my 48V 4S2P setup, I have 48 cells to check. Sucks.

Click to expand...

Then you better not buy these batteries. That's 24 batteries X 3 cells each = 72 total.

I'd just do like my neighbor and buy 1000Ah 2V cells. 24 and done.