The difference between battery in series and in parallel

In a Battery Pack, multiple batteries are connected in series to obtain the required operating voltage. If what is needed is higher capacity and higher current, then the batteries should be connected in parallel. There are also Battery Packs that combine both series and parallel methods. A laptop battery may consist of four 3.6V lithium-ion batteries connected in series for a total voltage of 14.4V; then two sets of batteries connected in series are connected in parallel, so that the total power of the battery pack can be Increased from 2000mAh to 4000mAh. This connection method is called "four-series-two-parallel", which means: connect two battery packs connected in series by four batteries in parallel.