The total energy stored in a battery (theory/formula)

[feynman1]

What's the total energy stored in a battery that can be expended in a circuit until it's depleted?

 

[russ_watters]

QV.

 

[berkeman]

What's the total energy stored in a battery that can be expended in a circuit until it's depleted?

Check the datasheets at the manufacturer websites. The energy storage depends on the battery chemistry, size, primary/secondary type, etc.

https://data.energizer.com/

 

[Merlin3189]

May I suggest that you add a bit of context to your questions? This one is not easily answerable as it stands and maybe some further explanation might allow us to say something useful.

Berkeman has given the correct answer. I would add batteryuniversity.com

By way of explanation take for example a simple Leclanché cell. The energy in this comes from a zinc electrode. As the metallic zinc dissolves and becomes a solution of zinc ions ($Zn -> Zn^{2+} + 2e^-$ ) it causes an emf (about 1.5 V) between it and the carbon cathode.
Faraday's electrolysis law tells us how much electricity can be obtained from any given amount of zinc, but there are two (at least) problems. First, you can't predict exactly how much of the zinc electrode can dissolve before it disintegrates. Once part has broken off the main electrode, it can't contribute any current. Secondly, the 1.5 V emf is the ideal emf when no current is flowing. As soon as current flows, the available emf at the terminals is a bit less. There is internal resistance as the current moves through the electrodes. There are chemical changes, such as, changes in ion concentrations around the electrodes and formation of hydrogen gas at the carbon cathode, which alter the 1.5 V emf. These vary both with the current and over time.

So the actual energy capability of the battery is not determined solely by properties of the battery, but also by the way it is used. A battery may be able to supply more energy into a small intermittant load than into a large constant load. Most batteries lose energy even when not used, because some of the chemical processes may happen even when they are not supplying current. The rate of these wasteful reactions may vary with temperature at which it is stored.

Even if you know all the details of the battery and of your useage, the answer is still likely to be a statistical one.

So what is it that you actually need to know?

 

[feynman1]

May I suggest that you add a bit of context to your questions? This one is not easily answerable as it stands and maybe some further explanation might allow us to say something useful.

Berkeman has given the correct answer. I would add batteryuniversity.com

By way of explanation take for example a simple Leclanché cell. The energy in this comes from a zinc electrode. As the metallic zinc dissolves and becomes a solution of zinc ions ($Zn -> Zn^{2+} + 2e^-$ ) it causes an emf (about 1.5 V) between it and the carbon cathode.
Faraday's electrolysis law tells us how much electricity can be obtained from any given amount of zinc, but there are two (at least) problems. First, you can't predict exactly how much of the zinc electrode can dissolve before it disintegrates. Once part has broken off the main electrode, it can't contribute any current. Secondly, the 1.5 V emf is the ideal emf when no current is flowing. As soon as current flows, the available emf at the terminals is a bit less. There is internal resistance as the current moves through the electrodes. There are chemical changes, such as, changes in ion concentrations around the electrodes and formation of hydrogen gas at the carbon cathode, which alter the 1.5 V emf. These vary both with the current and over time.

So the actual energy capability of the battery is not determined solely by properties of the battery, but also by the way it is used. A battery may be able to supply more energy into a small intermittant load than into a large constant load. Most batteries lose energy even when not used, because some of the chemical processes may happen even when they are not supplying current. The rate of these wasteful reactions may vary with temperature at which it is stored.

Even if you know all the details of the battery and of your useage, the answer is still likely to be a statistical one.

So what is it that you actually need to know?

Thanks a lot. I want to know what determines the 't' in the battery energy emf^2/r*t.

 

[russ_watters]

Thanks a lot. I want to know what determines the 't' in the battery energy emf^2/r*t.

Battery capacity is determined by its chemistry. But where did you see that equation? As far as I know it is not used to describe battery capacity (but could be used for measurement).

 

[feynman1]

Battery capacity is determined by its chemistry. But where did you see that equation? As far as I know it is not used to describe battery capacity (but could be used for measurement).

that's an equation i invented

 

[anorlunda]

The OP question has been adequately answered. Thread closed.