Where is my mistake?

[JacoTaco]

So I bought a battery bank from Jag35. It’s the Sony 24v bank with 112 26650 cells. I’ve already harvested the cells.

My question is since each cell is 3.2v and 3000maH, and there are 112 cells, wouldn’t the total aH rating be 112*3000? And come out to a total of 336 aH?

I did damage one of the cells. I shorted it out while removing the spot welds. And it happened QUICK! So my plan is to make a 25p/4s 12v battery. So, 25*3000mah at 3.2v = 75 aH at 3.2v.
4*3.2=12.8v 75aH*4 = 300ah.

This sounds too good to be true. Will this really end up being a 12v 300aH battery?

 

[snoobler]

Nope.

3.2 * 3Ah * 112 = 1075.2 Wh

1075.2Wh/12.8V = 84Ah.

3.2 * 3Ah * 100 = 960Wh

960Wh/12.8V = 75Ah

 

[Dzl]

So I bought a battery bank from Jag35. It’s the Sony 24v bank with 112 26650 cells. I’ve already harvested the cells.

My question is since each cell is 3.2v and 3000maH, and there are 112 cells, wouldn’t the total aH rating be 112*3000? And come out to a total of 336 aH?

I did damage one of the cells. I shorted it out while removing the spot welds. And it happened QUICK! So my plan is to make a 25p/4s 12v battery. So, 25*3000mah at 3.2v = 75 aH at 3.2v.
4*3.2=12.8v 75aH*4 = 300ah.

This sounds too good to be true. Will this really end up being a 12v 300aH battery?

I believe, you are engaging in 'have your cake and eat it too' math. A given configuration for a given number of cells can never increase both voltage and amperage.

Combining in parallel = amp-hours increase,
Combining in series = voltage increases.

25P4S = 25*single cell amp-hours, 4*single cell voltage = 75Ah 12.8V
Amp hours x voltage = Watt hours = 960Wh

 

[JacoTaco]

I believe, you are engaging in 'have your cake and eat it too' math. A given configuration for a given number of cells can never increase both voltage and amperage.

Combining in parallel = amp-hours increase,
Combining in series = voltage increases.

25P4S = 25*single cell amp-hours, 4*single cell voltage = 75Ah 12.8V
Amp hours x voltage = Watt hours = 960Wh

You are absolutely correct. And I figured it out as I was walking upstairs from my garage. And I should know better, V=I/R. This is truly one of those ImADummy moments, smh.

 

[Dzl]

ImADummy moments, smh.

I am very familiar with those moments

 

[snoobler]

You are absolutely correct. And I figured it out as I was walking upstairs from my garage. And I should know better, V=I/R. This is truly one of those ImADummy moments, smh.

What's worse is when you do it again...

V = I * R

You are amongst friends. This is a safe space.