Batteries are cheap, small and relatively safe way of having portable energy source. There are many types of batteries with different characteristics and uses. Probably many of you heard terms battery and cell referring to the same. But from technical perspective these are different things – cell is a single unit which houses a single chemical reaction and produces electricity, while battery is a pack of cells. Nominal cell voltage and battery voltage For instance single AA battery can be called a cell because this is a single unit where single chemical reaction generates voltage of 1.5V, but car lead-acid battery have six cells producing 2.0V each while all battery produces 12V. So first important thing to remember that single cell can produce specific nominal cell voltage that depends on chemical reaction, while battery voltage is a combined voltage of multiple cells connected in series (or parallel).