A watt-hour represents a unit of energy equal to one watt drawing power for one hour. Since batteries are storage units for electrical energy, watt-hour specifications equal battery capacity. For Energizer batteries, the manufacturer chooses milliamp hours rather than watt-hours. To convert milliamps to watts, it becomes necessary to convert milliamps to amps (1,000 milliamps in one amp), and then use the formula watt = amp x volt.
A standard Energizer AA battery, like all AA batteries, has 1.5 volts. With the constant voltage determining the watt-hours, specification becomes a matter of obtaining the Energizer specifications in milliamp hours and performing a conversion. Data sheets for Energizer's technical information can be searched on their website. For their AA battery, it looks to have a capacity of 2800 milliamps hours, or 4.2 watt-hours.
The voltage on the industry standard 9-volt battery is, obviously, 9 volts. Energizer's 9-volt battery's milliamp hours equal 610, or 5.49 watt-hours. Thus, the 9-volt battery has a greater capacity than the AA, which means that it is likely a 9-volt Energizer battery will outlast a AA battery.
All AAA batteries, a smaller size battery than AA, are 1.5 volts. Energizer's AAA battery has a capacity of 1250 milliamp hours, or 1.87 watt-hours, giving the AAA battery considerably less capacity than a AA battery.
With the same voltage of a AA or AAA battery (1.5 volts), the C battery differs in that it has a milliamp capacity of 8,200. When converted to watt-hours the number becomes 12.3 watt hours, demonstrating the difference in battery capacity among the smaller AA and AAA as opposed to the larger C.
With a larger size than a C battery but the same 1.5 voltage, D batteries should have a greater capacity. A specification of 21,000 milliamp hours, or 31.5 watt-hours, gives the D battery more than two and one-half times the capacity of the C battery.
- Photo Credit ballyscanlon/Stockbyte/Getty Images
Eveready Gold Vs. Energizer
Though many different types and brands of batteries cover the market, not all are meant for use in all products. Some last...
Definition of Laptop Battery WHr
When you're comparing laptop batteries, you need a practical way to contrast them side by side. The amount of charge they can...
12 Volt Vs. 6 Volt Batteries
Considered low-voltage batteries, 12-volt and 6-volt batteries are similar in basic construction; they are both categorized as lead-acid batteries. However, they differ...
How to Calculate Milliamps
Ohm's Law is the basic formula for electronics. With it, we may calculate Resistance (Ohms), Voltage (Volts) or Current (Amps) by knowing...
How to Calculate Battery Watt-Hours
If you're a recreational vehicle owner, knowing how long your battery will provide power is important. And that's because your battery will...
How to Calculate How Long a 9 Volt Battery Will Last
Known originally as "PP3" batteries, rectangular 9-volt batteries continue to be very popular with designers of radio-controlled (RC) toys, digital alarm clocks...
How to Calculate Watts From Batteries
Batteries produce voltage and amperes. Voltage always remains constant and is the amount of electricity flowing through a wire from the battery...
Watt Hour Vs. Amp Hour
Electricity carries energy that you can measure in several different ways. Power, the rate at which equipment uses energy, is expressed as...