What is battery power density?

Power density:

It defines power capacity of a battery for a given mass of volume.

For example 100 Wh/Kg (Alkaline battery standard power density) implies that for 1 Kg of chemical composition it provides 100 Wh of power capacity.

Now, volume of a AAA alkaline battery is 11.5 grams. So if 1Kg can give 100 Wh capacity, then how much a 11.5 gram AAA battery can give?? 

Let’s calculate.

Wh (for 11.5 gm) = 100*11.5/1000 = 1.15 Wh

 

So, we know the nominal voltage of alkaline battery is 1.5V. So it provides 1.5V * (1.15/1.5)A * 1 hour gives 0.76 Ah = 760 mAh of power capacity which is almost equal to the power capacity of a standard AAA alkaline battery.