18650 - This is the most common standard for a Li-Ion battery (or Cell in correct technical terms). In your Laptop, usually multiple 18650 cells are connected in series to provide a higher voltage. A 2-cell battery (Multiple cells connected together is technically called a battery), will have 2 cells in series and produce 7.2 to 7.4 Volts. The Power Bank that we talked about in my earlier post usually comprises or 1 or more 18650 cells - But these are connected in parallel. There are wild claims regarding the capacity of power banks and 18650 cells as well. So lets make it clear here - The Size of a 18650 cell is 18x65mm. In that space there is little room for wild swings in capacity - The Chemistry is nearly the same. So we have real capacities ranging from 2,000mAH to 3,100mAH. Cell capacities are Colour coded (You can check the details in one of the links below). The Purple Colour Cell manufactured by Samsung is one very commonly available battery...