18650 Milliamp to Amp Hour Question

[DaddyOh]

I think I have been doing too much reading lately that I am not seeing the forest in all of those trees. Need to clarify, in very easy terminology

You have 35 lithium batteries 18650/3.7V. They are arranged in 7 'banks' to equal a voltage of 25.9V, each 'bank' will have 5 batteries in parallel... so a 7S/5P battery pack.

For sake of my question, you do a capacity test on each of the 35 batteries and find 'miraculously' each have a milliamp capacity of 1700mAh.

Question: To determine the amp hour rating of this battery pack, do you take the capacity of each 18650 battery, add them up and divide by 1000? In this example that would be 1700 x the 35 batteries which would total 59,500mAh... if you divide that by 1000... that would be a 24V (25.9V) 59.5 amp hour battery. Somehow that seems inaccurate.

I initially thought I had a good handle on it but now... after much reading, am confusing myself.

 

[DaddyOh]

Intially I thought, each bank of the 7 would be balanced in capacity. So, in the example each 'bank' would have 5 batteries in parallel, each at 1700mAh. So, 1700 x 5 would equal 8,500mAh... then divide by 1,000 would yield a 8.5 amp hour rating of the pack... highlighting the need to run capacity tests and balance each bank. At this point....just confused

 

[Hillhater]

You are nearly there..
Add capacity (Ahr) of Parallel cells
Add voltage of series cells
so you are correct with 7S = 25.9 volts...and 5P = 5x1700 mAhr =8500mAhr, which is 8.5Ahr