# Battery Pack Life Rating

I am working off of a schematic where I was given a battery pack with the following specifications. The battery being used is a panasonic NCR18650 lithium ion cell. https://engineering.tamu.edu/media/4247819/ds-battery-panasonic-18650ncr.pdf

The battery pack is stated to have 84 cells in each series string and 79 strings in parallel.

The total amount of cells is 6,636 cells (84 * 79).

The pack voltage rating is given as 302V and the total pack current is given as 236 Amps.

The nominal voltage for this battery is 3.6V so 3.6 x 84 = 302.4 which indicates the pack voltage.

Where I am confused is how the total pack current of 236 Amps is being obtained. 79 strings of cell in parallel would add the total capacity of the batteries.

The capacity of one cell is 2,900 mAh. I would think that the total pack current should be 2,900 x 72 = 208,800mAh or 208.8 Amps.

I am not seeing where the value of 236 Amps is being obtained.

What is also confusing to me is the battery pack has a life estimation of 2,800 seconds at a rating of 300V @ 3 Amps.

The equation for battery life is the battery capacity divided by the load current. I have not found a way to make these numbers make sense.

Is there anything that I am overlooking in this calculation, that would cause me to obtain the specified values? Any insight is appreciated.

• You question reads like a high school math test. Could you clear up the wall of text? – Jeroen3 Jun 5 '18 at 18:05
• If you don't know the difference between amps and amp-hours, you certainly shouldn't be working on a 350kg battery. – Brian Drummond Jun 6 '18 at 8:49
• @BrianDrummond, correction, "on a 350kg Li-Ion battery" -:( – Ale..chenski Jun 6 '18 at 13:59