What is Battery: Definition and 1000 Discussions

A battery is a power source consisting of one or more electrochemical cells with external connections for powering electrical devices such as flashlights, mobile phones, and electric cars. When a battery is supplying electric power, its positive terminal is the cathode and its negative terminal is the anode. The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal. When a battery is connected to an external electric load, a redox reaction converts high-energy reactants to lower-energy products, and the free-energy difference is delivered to the external circuit as electrical energy. Historically the term "battery" specifically referred to a device composed of multiple cells, however the usage has evolved to include devices composed of a single cell.Primary (single-use or "disposable") batteries are used once and discarded, as the electrode materials are irreversibly changed during discharge; a common example is the alkaline battery used for flashlights and a multitude of portable electronic devices. Secondary (rechargeable) batteries can be discharged and recharged multiple times using an applied electric current; the original composition of the electrodes can be restored by reverse current. Examples include the lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as laptops and mobile phones.
Batteries come in many shapes and sizes, from miniature cells used to power hearing aids and wristwatches to small, thin cells used in smartphones, to large lead acid batteries or lithium-ion batteries in vehicles, and at the largest extreme, huge battery banks the size of rooms that provide standby or emergency power for telephone exchanges and computer data centers.
Batteries have much lower specific energy (energy per unit mass) than common fuels such as gasoline. In automobiles, this is somewhat offset by the higher efficiency of electric motors in converting electrical energy to mechanical work, compared to combustion engines.

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  1. P

    Car Modification: Using your battery to prevent rust

    Hypothetically speaking, if you wanted to prevent rust on your car frame, how would you wire your battery to your frame?
  2. badr

    Silly question about series batteries

    Hi everyone. So I am making a Ni-Mh battery , and for space constraints, I need to put 2 batteries in paralell + 1 battery in series with them. So if I get two batteries of 2100 mah in paralell I get 4200 mah, but if I put them in series with one 2100 mah battery , what would be the...
  3. L

    Does the voltage across a battery include its internal resistance?

    I am uncertain if this represents situation (a) or situation (b). i.e. is 2 = E-iR or is 2 = E? Or is the question ambiguous? Thanks!
  4. L

    Introduce a battery to an LR circuit

    Let's say I have an LR circuit. I understand the mathematical derivation of this but would like to understand it conceptually. Okay, so a battery is introduced (let's say 12 V). The inductor hates the change, so it induces 12 V in the opposite direction, opposing the battery. So what happens...
  5. Z

    Why is source force + electrostatic force = 0 inside battery?

    If a battery is in a closed circuit, we have an electrostatic field ##\vec{E}## from the positive terminal to the negative terminal of the battery through the circuit outside the battery. This field generates current. Inside the battery, the electrostatic field lines go from positive to...
  6. L

    Is current flowing into a battery always equal to current flowing out?

    Image from Wiley Intro Physics Textbook sample problem This was the given problem. In the diagram, one can see that the current flowing into each battery equals the current flowing out of each battery. Is this always the case, and why? If there was only one battery, I guess it could be...
  7. davidjoe

    I Battery life on VERY fast moving object

    Accepted thinking is that time slows as speed increases, relative to a non-moving reference frame. But supposing that the object approaching C is a ship in rotation around the earth, and on that ship is a laser mounted on a gimbal such that the laser is always pivoting and trained on exactly...
  8. Z

    Circuit with potential difference across battery being zero?

    Using KVL we have ##\epsilon_1-\epsilon_2+iR=0##. It seems that ##\epsilon_1,\epsilon_2##, and ##R## are given and the only variable is ##i##. Thus, ##i=\frac{\epsilon_2-\epsilon_1}{R}## for the KVL equation to be true. However, it seems like when we think about what happens to this circuit...
  9. Z

    Why do the headlights on the car become dim when the car is starting?

    Suppose we have 12V battery. Though I can solve electric circuits, there are some very simple practical concepts that are gaping holes in my knowledge. What does it mean for a circuit device to "pull a lot of current"? What is a simple circuit element that when I connect it to the battery it...
  10. leVanw

    The battery voltage drops when fed to the DC booster circuit

    I use a 12V battery to power a DC booster circuit. After just a moment, my battery's voltage decreased, causing the booster circuit to also decrease its voltage. Is there any way to make the battery last longer without losing voltage? Thanks
  11. L

    Do they have powerful battery packs that can run a vacuum?

    For those that have to vacuum large spaces often have to use many different outlets and worry about running over their own cord. Is there a battery pack one can strap to their back to power a vacuum cleaner? Or would that amount of power tide to a person be dangerous?
  12. W

    Computer powered off, despite being plugged in. Battery wasn't charging...

    Hi, So, PC powered of all the sudden, wont power on. Battery had not been charging when PC was plugged in. So, can I conclude neither battery nor power cord are working well? I guess my options for doing something to have battery recharge are limited, given PC won't power on. Do I have any...
  13. hagopbul

    Question about battery -- Looking into the electrode effects on the battery

    Hello All : i had few suggestions about battery enhancement using some ideas which i had just abstract understanding not enough even to suggest discussion but i have this question why we dont fold the anode and the cathode into geometrical shape , wouldnt that increase the number of...
  14. Z

    How do we obtain an ampere-hour rating given voltage and watt-hour?

    The solution is thus 0.69 ampere-hours, or 690 mA-hours. Now, as far as I can tell, an ampere-hour is unit of charge. That is we can convert it to coulombs (C). For example, if we have a current of 1A for 1h, then we have 1 C/s x 3600 s = 3600 C = 1 ampere-hour. This is my guess since the book...
  15. J

    Optimum Battery (and Wire) to Power 10x Mini 1.5V Bulbs in Parallel?

    TL;DR Summary: We purchased a 9v battery box and planned to wire it—in parallel—to 10 mini bulbs, assuming 10 bulbs drawing from the 9v would be more than enough voltage drop to not go up in smoke. We purchased a 9v battery box and planned to wire it—in a parallel circuit—to 10 mini bulbs...
  16. lukakopa7

    Battery protection circuit board

    Does anyone know a cheap(available on Ebay/AliExpress ) battery protection circuit board that has undervoltage/overvoltage protection and charging capability? I have a 3.7v Li-po battery and I need to draw 5 Amps from it.
  17. DagmaarUlereich

    Outlet adapter to mimic a car battery to power 12V devices

    Sorry if this is a very simple question but i have been googling and looking around for a straight anwser but can seem to find a solid answere or draw a solid conclusion from information I've reached. So I have a rgb led light for a car, the box says input 12vDC. if I wanted to set these up...
  18. M

    Ranking charge stored on three capacitors by a battery

    For this problem, The solution is, I have a few questions about parts of the solutions, - Part(b): (1) Why do they assume that the capacitors are initially uncharged? Do they even need to make that assumption because it seems clear to me that we are finding the charge stored by each...
  19. S

    Adjustment of Variable Resistance in an automobile battery

    How is the load (variable resistance) adjusted in an automobile battery? Mechanically (potentiometer, rheostat) or electronically (digital potentiometer) or are both configurations possible.Can the load in a automobile battery be a three terminal divider (potentiometer) or is it almost always...
  20. S

    Battery circuit current flow when charging

    I would like to know when a alternator is charging a battery is the current flow a series opposing circuit......?
  21. S

    Electrical What does a Roomba battery "reset" do?

    A suggested fix for a Roomba 500 series with a battery that won't hold a charge is to hold down the "spot" and "dock" buttons to "reset" the battery. (e.g. ) What, physically, does this do? Does it completely discharge the battery? Does it change some setting in the computer that...
  22. bmhiggs

    Recharging a Battery With a Hand Crank?

    Could a normal rechargeable battery (meaning the kind you plug into a usb port or electrical outlet) be recharged with a hand crank generator (assuming it was generating a sufficient voltage)? Would there need to be some kind of converter to make it possible, or just connect some +/- leads? I'm...
  23. Leo Liu

    Analyzing the Effects of Battery Position on ##C_m-\alpha## Graph

    I am trying to determine how the addition of a counterweight affects the ##C_m-\alpha## (in longitudinal direction) graph for a model plane project, where the counterweight can be considered as the battery. Suppose we try to place the battery at the back of the current CoM. The new CoM will...
  24. dlgoff

    Panasonic has announced it will begin building its EV battery

    I moved to Kansas from Arkansas when my father got a job at the Sunflower Army Ammunition Plant in Desoto Kansas. Now that plant will be making Batteries for electric autos. I wish my dad was still alive to see this.
  25. Wrichik Basu

    What is the correct way of measuring remaining battery capacity?

    I was searching for a way to measure the remaining charge of a battery using Arduino. Most (almost all) of the tutorials are simply measuring the battery voltage using the ADC on the Arduino. The calculations are pretty straightforward after that — ##5 V## is mapped to ##1023## and ##0## is...
  26. dlgoff

    New Car Battery Plant Construction in the Midwest

    Panasonic is going to build an electric car battery factory plant in DeSoto, KS. Will hire 4000 jobs at the plant and another 4000 jobs throughout the state. IIRC, the factory will cost 4 billion dollars to build. edit: corrected spelling of DeSoto
  27. Algr

    What continuous wattage can I get out of a 12v lantern battery?

    I have a C-Pap machine, and I'd like to put together something to power it for a few hours if we have a blackout. Wiring two of the above lantern batteries together should produce 24 volts. But I can't find any info on how much wattage you can draw from these before the voltage will sag. It...
  28. neilparker62

    B Troubleshooting Battery Internal Resistance Measurements

    Have been busy working with a student doing a Physics prac to determine the internal resistance of an AA 1.5 V (nominal) battery. The basic formula being investigated is: $$Vt=E_{cell}−Ir_i$$ where ##Vt## is the load (resistive only) voltage, ##E_{cell}## is the emf of the AA battery, ##I## is...
  29. S

    Android: API to control battery protection mode?

    My new Lenovo tablet has a "battery protection mode". This is useful for example when you want to leave it on charge almost permanently, in which case the protection mode will charge and discharge between 40% and 60% in order to maximize battery life. Is there an API that can enable/disable...
  30. theycallmevirgo

    What is the basis for Toyota's fluorine battery claims?

    Google top result says Toyota is researching Fluorine batteries that they claim will have 7x energy density of LiIon. However my textbook table of reduction potential gives lithium as higher than fluorine. Any idea what they base their claims on? Thanks Joe
  31. V

    Do electrons flow through a battery or is it something else?

    This is a confusing question. I am not sure if electrons flow through the battery from positive terminal to negative terminal against the electric field within the battery; or the electrons deposit on positive plate resulting in a chemical reaction that releases electrons at the negative plate...
  32. X

    B A muon enters a lithium battery....

    Just wondering what would happen if a muon entered the LiH dense environment of a lithium battery. Could it explain the instances of spontaneous combustion of the battery in electric vehicles? Li + H => He
  33. A

    I Calculating Total Electric Charge with a Capacitor and Battery

    With a capacitor with a dielectric with the battery on, ##E_{total} = E_0 + E_i## ##\frac{Q_t}{dC_t} = \frac{Q_0}{dC_0} + \frac{Q_i}{dC_i}## thus, ##\frac{Q_t}{C_t} = \frac{Q_0}{C_0} + \frac{Q_i}{C_i}## since in a battery ##V_t = V_0, V_i = 0##, so either ##Q_i = 0## or ##C_i = infinite## but...
  34. S

    Why would disconnecting the positive cable first on car battery cause sparks?

    When I was 18 years old, I worked at an automobile repair shop doing oil changes and other light mechanical work. The automobile repair shop hired me for this work to free up their real auto mechanics to do more advanced automobile repair work. One time I was assigned the task of replacing a...
  35. Lars Krogh-Stea

    B Energy Conservation w/ Charged Battery Time Travel

    Hi! I want to start with saying that I'm not an expert on these type of problems, but I will be gratefull for some calarifications. I've heard that there's nothing in psysics that says that time travel is impossible. I want to make a case with the time traveling battery. Could be any mass with...
  36. moriah

    Can I Use a 6V Battery for Electrolysis?

    I’m assuming 6V is a suitable battery for such process. The terminals on this type of battery are different from what I’ve seen on other types. The positive terminal is “capped” with black plastic. With this cap intact, would I be able to generate electrolysis?
  37. dRic2

    Low battery life in sleep mode

    I have a 6 years old MacBook air, still running the OS of a couple of years ago. Lately, battery life is going down (around 4.5 hours of light/medium use) so I mainly use it as a desktop computer, connected to an external monitor. However, when I leave it in sleep mode (still on, but shell...
  38. John Mohr

    B Does a DC Cell or Battery Actually Supply Electrons?

    I have held the assumption that batteries supply electrons at the negative terminal and absorb electrons at the positive end for many years. However, after watching this video at about 3:30, it is said that batteries do not actually supply charged particles but that the battery only creates an...
  39. PhysicsTest

    Are higher voltage batteries safe for electric vehicles?

    I have few questions on the battery voltages for electric vehicles. Some vehicles operate at 48V battery and when i read the standards regarding these they mention above >60 V is hazardous and may lead to electrical shock and shall be avoided under all conditions. But i also see batteries with...
  40. S

    I What is the energy output of a Gravity Battery System?

    I have been seeing quite a bit of news on Gravity Batteries, and am curious about the actual energy generated from the stored GPE ? I know GPE = mass x height x gravity h = 50 ft m = 6000 lbs g = 32.2 ft/sec^2 GPE = 9,660,660 joules = 2.68 KWh But what is the actual energy output from this ...
  41. Dario56

    I Energy Flow From Battery to the Light Bulb

    When we connect tungsten filament light bulb to the battery, filament becomes hot due to electrons losing kinetic energy in the electric field inside of conductor. Heat is eventually converted to electromagnetic radiation making light bulb shine. Light energy comes from flow of electrons and...
  42. Y

    Why can a capacitor be charged by a battery (DC)?

    Hello there, I'm perplexed as to why the capacitor is DC-blocking, but the battery (DC) may charge the capacitor. I'd never considered it until I recently read it in a book. I honestly have no idea what's going on. If anyone has any idea why this happens, please let me know. I've read some...
  43. S

    Engineering Using Kirchhoff's Laws to Solve a Circuit with Two Batteries

    Okay so This is what I've tried; a) A formula I've found in the lecture notes; $$ U_a = U_q - R_i*I $$ To get I used the ## I = \frac{P}{U} ## formula I get I to be 0,46 A.Now put back in formula for and rearange to get Ri should be $$ \frac{Ua-Uq}{I} = Ri $$ and the solution should be 0,43...
  44. bob012345

    Electrical Emergency Battery Backup System for TV/Internet During Power Outages

    I am looking for the right size of battery/pure sine-wave inverter to power a system for a few hour when there is a power outage. The system of TV/DVD/Internet uses less than 200 watts at about 1.6Amps. I could just buy a commercial system which runs about 1000$ or assemble a similar design for...
  45. B

    Calculating particle numbers in diffusive equilibrium of a battery

    So I think I have the principles mixed up here because I'm getting kind of "circular" answers. ## N = N_1 + N_2## ##dN## = 0 bc/ particle number fixed so ##dN_1 = -dN_2## ##F = cN^2 = c(N_1 + N_2)^2## In diffusive equilibrium, free energy would be minimized and chemical potentials equal... $$...
  46. Solitron

    Battery - theoretical specific energy

    I want to learn how to calculate maximum theoretical specific energy of various battery combinations consisting of a single metal and single oxidant, like for example Sodium - Sulfur, Potassium - Sulfur or even crazy stuff like Rubiddium - Iodine. I asked this question on stackexchange but I...
  47. nazmulhasanshipon

    Comparing energy lost by the battery & energy gained by the capacitor.

    Imagine the two terminal of a *parallel-plate capacitor* are connected to the two terminal of a battery with electric potential difference #V#. If the capacitance of the capacitor is #C#, and the area of each plate is $A$. In this process would the energy lost by the battery and the stored...
  48. S

    Gato / Balao Submarine "Can't" vs "Must" Surface on Dead Battery

    I've read a lot about Gato / Balao / Tensch class submarines, the ones America used in WWII, and I can't seem to sort out the specific consequences of a dead battery. A lot of you are diesel experts, so maybe someone here knows? Historical accounts are vague. Dead batteries are certainly a big...
  49. T

    Key fob only works on battery and not power supply. What?

    Yesterday the batteries died on my key fob and I didn't have the appropriate batteries to replace them. I thought I could use my power supply to operate the key fob to open the car door but it did not work. I thought that it may be caused by a noisy power supply at the higher frequency range of...