# Q & A: Batteries, Volts, and storage energy

Q:
Is a volt how much energy the battery has?
- Jane (age 14)
Chicago,Il, USA
A:

Hi Jane,

Many alkaline batteries, for example A, AA, AAA, D, etc. have the same voltage but much different amounts of stored energy.   The voltage of these batteries is around 1.5 Volts irrespective of their size.  In general the amount of energy stored is proportional to the weight of the battery.  Other types of batteries have different voltages, for example a lead-acid battery has a voltage of around 2 volts per cell.  Battery voltages are determined by the chemical make-up of their individual chemical constituents.   One can make batteries with several cells connected in series.   For example a car battery can be made up of six lead-acid cells to make up 12 Volts.

See:    or .

Now, the voltage of a battery is not the total amount of energy stored but represents the potential of supplying a certain amount of current in a circuit :   I = V/R  where I is the current, R is the resistance and V is the voltage. The total energy stored is proportional to V times the total available charge due to the chemical reactions.   This charge is directly related to the size and weight of the battery.

LeeH

(published on 05/05/2014)