ORIGINAL: Jeremy Z

Let me break it down for you:

C = battery capacity. So when they say "20C" it means the maximum discharge rate is 20 x the capacity of the pack. So on a 5000 mAh pack, you could discharge it at 100 A. (20 x 5 A or 5000 mA)

P = # of parallel cells. Paralleling cells doubles capacity but the voltage remains the same. So if you have a 2P pack, it means there are two sets of cells in parallel.

S = # of series cells. This is how you think of Ni chemistry packs. In Nickel packs, all the cells are in series. Capacity is determined solely by the capacity of each cell. Once in a while, someone will parallel nickel cells, but not often.

So, for example, if someone wrote 4S2P 20C 5000 mAh:

It means 4 series sets of 2 parallel cells. Each LiPo cell is 3.7 V nominal, so the voltage will be 14.8 V. Each cell has a capacity of 2500 mAh, so paralleling them yields the 5000 mAh.

More important is the capacity, 5000 mAh. Nothing complicated here, and the discharge rate. Don't use it in a set-up that will draw more than 100 A, or your puff it and ruin it.

You'll need to get a balance charger to keep the cells in balance, so they charge evenly and don't puff or burst into flames.

I came from planes, where LiPo is the norm. There are penalties in price & safety for LiPo great weight & size advantage that is offered.

IMO, you're better off with nickel battery packs and brushless motor/controller for now.