What is Batteries: Definition and 461 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. Maghraby

    Homework help : The difference between these 2 circuits

    I want to know the difference between the two circuits below , and Why don't I bundle both batteries into one 24V battery? pls help me in this . This is the original circuit: And to merge the two batteries , What is the resulting value of a battery resulting from the merger? I thought...
  2. T

    Connect parallel batteries with wrong poles

    I would like to do now (theoretically) a couple of rather naive things with two batteries with voltages ##V_1## and ##V_2## in parallel charged with an abstract load with resistance ##R##. Usually, one learns in elementary electronics that the only "right" configuration with batteries in...
  3. T

    Safer Lithium Ion Batteries - a Significant Step

    The folks at MIT have found a way to avoid the dendrites that short-circuit Li Ion batteries. This will allow getting rid of the very flammable liquid electrolyte. https://news.mit.edu/2022/controlling-dendrities-lithium-batteries-1118 Cheers, Tom
  4. M

    I Energy and sand batteries (thermal energy storage)

    Hi, I'm new here, so apologies if this is covered somewhere else. I'm just playing with the notion of building a sand battery. Sand has a spec heat cap. of 830j/kg degrees K. If I want to heat 1000kg of sand up to 400 deg c, by my rough calculations that will require 332 000 Kj of energy, or...
  5. Synco

    Big doubt about graphene in batteries

    Well people i'm looking electric Motorcycles. And the same seller it's selling a 72V50Ah battery and a 72V60Ah battery, both IN THE SAME WEIGHT, every battery in the shop occurs the same. So or we have a factory mistake, scam, witchery .....or...graphene in the lithium. I have been reading that...
  6. Astronuc

    Lithium-Sulfur Batteries? Maybe

    Lithium-Sulfur Batteries - Earthwise with Randy Simon https://earthwiseradio.org/podcast/lithium-sulfur-batteries/ Breakthrough in Cathode Chemistry Clears Path for Lithium-Sulfur Batteries’ Commercial Viability Stabilization of gamma sulfur at room temperature to enable the use of carbonate...
  7. T

    Misc. Looking for entry level DIY ideas

    I'm looking for a way to use these batteries that is safe and also useful. I've looked into buy inverters to turn them into portable battery packs but am out of my depth and don't want to create a device with serious potential fire hazards without thoroughly understanding the ins and outs and...
  8. J

    Finding the Best Batteries for a 48V EV Motor

    How did you find PF?: Google Search Hi have a 48 Volt EV motor of which I will be modifying for belter performance I am unsure of the specs i have contacted the supplier and awaiting a call back I have Toyota coaster And I am allowing up to 5000 KG in Weight How many batteries do I need and...
  9. K

    Question about Lithium batteries

    If a rechargeable Lithium battery is new and not used for a few years, will it degrade much slower or as fast as the one that is regularly used, charged and discharged? What if I only start to use it after a few years for the first time, will the battery already degrade so badly
  10. jmansurf

    Interested in flywheel mechanical batteries

    Can someone point me to advanced engineering/ physics based literature / textbooks on the subject?
  11. DaveC426913

    "Magic" AA batteries in a home device?

    I am mystified. My number-combo door lock (one of two I have) is powered by 4 AA batteries. It has been working for so long I don't remember when I installed it - musta been ten years at least. The batteries have begun to run down - it labours to retract the dead bolt now - so it's time to...
  12. patric44

    Power dissipated in this circuit with 2 batteries and 3 resistors

    Hi guys I am struggling to find the power dissipated in the total circuit , my answer didn't match the solution in the book the circuit is simple i used Kirchhoffs rules to find the following : loop 1 : $$10-10I_{1}-40I_{3} = 0$$ loop 2: $$20-20I_{2}-40I_{3} = 0$$ and $$ I_{1}+I_{2}=I_{3}$$...
  13. Dario56

    Internal Resistance of the Battery - Ohmic Resistance

    When current starts flowing in a circuit, voltage of the battery drops from EMF value. There are three sources of this however here I am only interested in ohmic resistance of the battery. EMF of the battery is created because of electrochemical processes on both electrodes which create...
  14. K

    Questions about rechargeable batteries

    In general, is it almost all rechargeable battery used in consumer market Lithium battery? Is there any different rechargeable battery today? Could rechargeable battery manufactured in low quality factory have any underlying health concerns? Could it release any radioactive substances? I am...
  15. narayan821

    Does DC or AC work best for charging most industrial batteries?

    I have a source of electricity that's alternating but at variable frequencies. So an asynchronous alternating current of sorts if you will. Can industrial rechargeable batteries be charged like this efficiently? Or would DC current work best? Or normal AC?
  16. ghowriter

    How to make a custom UPS using an old PC power supply and 18650 batteries?

    Yes, this is a question. I already converted an old PC power supply (350 Watt) to replace the bower bricks for my Internet modem and router. What I would like to do now is install a 2-3 hour mini-UPS in the mix so I can remove it from my computer's UPS. I have spent days online scouring the web...
  17. Y

    Float charging batteries: what really happens?

    A typical off grid solar system looks like this: PV Array -> MPPT controller -> Battery bank -> 240v AC inverter -> loads Suppose that the system is currently float charging: "Float charging, also called trickle charging, consists of charging the battery at the same rate that it is...
  18. R

    Electromotive Force, Batteries, Resistors, and Potential Differences

    I have attached a small excerpt from my digital book where they start talking about emf. I am very confused. Let me explain what is confusing to me so that you can clear up what's bothering me. They start of by saying that an emf device pumps charges by maintaining a potential difference...
  19. F

    Efficiency of charging new and old Li-ion batteries in electric cars

    An electric car has, say, a 50 kWhr battery. 1. How much electricity, in kWhr, is needed to add 1 kWhr of stored electricity to the battery? 2. After several years, the battery capacity has, say, fallen to 25 kWhr. How much electricity, in kWhr, is now needed to add 1 kWhr of stored...
  20. BWV

    Battery vs Hydrogen Power: Volkswagen's Efficiency Comparison

    Volkswagen recently published this graphic supporting their decision to focus on battery-powered EVs and abandon hydrogen fuel cells https://insideevs.com/news/406676/battery-electric-hydrogen-fuel-cell-efficiency-comparison/ however it does not include the energy and materials required to...
  21. B

    Me To Charge 18650 Batteries

    Hello Friends, Please help me to setup 5 [18650] Li-Ion battery of 11.1 volt I describe everything in image. Please check attach file Thanks in Advance
  22. Rzbs

    Lithium-ion rechargeable batteries

    I want to know how a lithium ion rechargeable cell works with very basics details. I don't need a simple describtion like most of the websites and videos. I need a resource that explain the chemistry and physics of a Li ion cell from very basics of knowledge. Could you please introduce such a...
  23. M

    Studying the theory behind batteries

    These days I've taken an interest in lithium ion batteries and the like, but I don't really know where to go to start learning about them. I saw the general engineering sources and the materials/chemical engineering sources threads, but there was nothing specifically about batteries- Does anyone...
  24. Kaushik

    Intuition about electromotive force (EMF)

    My understanding of emf Let us consider 2 parallel plates with charges (opp. but equal in magnitude) stored on it. When we connect both the plates from the outer side, the electrons from the lower potential (i.e., negatively charged plate) moves to the higher potential (positively charged plate)...
  25. P

    I Difficult Series Battery Problem

    Modern batteries use double-sided anode and cathodes for greater energy density. Series wiring of batteries is typically accomplished by connecting the anode of one cell to the cathode of another. However, can series be accomplished by stacking double-sided anode and cathode alternatingly with...
  26. Stonestreecty

    I How do I know the lithium content of a lithium-ion battery?

    Power bank is common for our daily life, especially for our smart phone, which always a lithium-ion battery. Taking airplane is easy at our daily life, but there are restrictions on lithium content for air travel, thus air travelers ask the question "How much lithium in a battery am I allowed to...
  27. J

    Chemistry Undergraduate-level text on batteries and battery management (with exercises)

    Is there such a thing? Or, alternately, am I just better off with an echem and/or physical chemistry book? Thanks Joe
  28. M

    Two batteries and two resistors circuit - wrong possible answers ?

    It's ABCD question with answers attached. Problem is that, I don't think that neither of those are correct. From KVL the equation seems to be i = (E2-E1)/(2r1+2r2 + R). I've attached images of the circuit, answers, and my solution. Can someone please point me if I am wrong, and if yes, where's...
  29. Lookitsame

    How do I properly charge my LIPO battery?

    Hey, I just purchased a lipo battery and was wondering if I wanted to charge it would I be able to use a 6v/3amp charger for the following lipo 7.4v/10amp. I'm pretty sure I would be able to. LIPO BATTERY: https://www.robotshop.com/ca/en/74v-2000mah-5c-lipo-battery.html What is the general...
  30. B

    Using Kirchhoff's laws for multiple batteries and resistors

    Hey everyone! Had an attempt at this circuit question, but wanted to check if I got the set up right in order to find the current in the 3rd wire? Here is what I have done Thanks!
  31. W

    Electrons @ battery negative terminal

    Does the negative terminal of a battery have a negative charge due to having a surplus of electrons? If so, then why do the surplus electrons from the negative terminal of the battery not discharge to the human body or Earth (which have a neutral charge) when touched?...thereby causing the...
  32. B

    Kirchhoff's law: Circuit problem with multiple batteries and resistors

    Struggling to see if I am doing this right or not from a section of a question I have been given I have drawn out a sketch of the circuit again, and labelled as to what my 1st and 2nd closed loop to be to then apply Kirchhoff's 2nd law I get a negative I_2 current which just indicates that...
  33. K

    Can I use plastic tape to fix the rips on batteries

    I bought a new battery of D size today but I noticed that there is some rips (not much), I am not experienced and I certainly won't rewrap the whole battery. I'd like to know if it's okay to use fix it by taping the part with a small plastic tape??
  34. E

    Clarification about the sign of EMF in batteries and electrochemistry

    In electrochemistry, we define ##E_{cell} = E_{cat} - E_{an}##, the difference between the electrode potentials of the cathode and the anode. This has the effect that if the reaction is spontaneous, we obtain a positive ##E_{cell}## and if it is not - i.e. we need an external driving voltage...
  35. nmsurobert

    Kirchhoff's Rules for analyzing this circuit with batteries and resistors

    Summary:: Choosing the direction of the loop and the current I am attempting to work out Example 1 in the link provided. https://courses.lumenlearning.com/physics/chapter/21-3-kirchhoffs-rules/ When solving for loop aefgh, I get: I1R1-I3R3-I3r2-E2 =0 I chose the current to continue to move...
  36. SchroedingersLion

    Batteries: Is the current a diffusion current?

    Greetings, I realized that I don't understand a fundamental fact of common Li-ion batteries. During the charging process, electrons are forcefully extracted from the cathode and pushed into the anode. Charge balance then yields a flow of positive Li ions from the cathode to the anode (through...
  37. S

    Battery Charge and Discharge Time Calculations

    I am performing some calculations but struck with confusion whether I am doing it correct or wrong due to contradictions of these calculations on different calculators websites. I hope here someone will help me with the validation of my calculations. Battery Capacity = 150 Ah Battery...
  38. N

    Are capacitors the superior alternative to lithium ion batteries?

    I'm an undergrad physics student, so, I don't yet know much about the technicalities behind using chemical batteries vs capacitors. However, from what I've learned so far, capacitors seem to be a far better option than lithium ion batteries - they're not hazardous (at least when discharged), do...
  39. M

    Would a giant orbital gravity battery be a good future power source?

    Gravity batteries intrigue me. We are starting to develop them now. We currently are able to drop cement blocks and harness the energy that the kinetic energy releases. We are considering them as an alternative energy source to help the environment. Here’s a link for those unfamiliar with it...
  40. lalallaland

    Two batteries with inner resistor in parallel

    I am kind of stuck at this exercise and I would like some help. Thanks a lot!
  41. L

    Circuit analysis: Six resistors and two batteries

    Problem Statement: ) A circuit is constructed with six resistors and two ideal batteries as shown. The battery emfs are ε1 = 18 V and ε2 = 12 V. The values for the resistors are: R1 = R5 = 55 Ω, R2 = R6 = 110 Ω, R3 = 44 Ω, and R4 = 117 Ω. The chosen positive directions for the currents are...
  42. C

    Redox Flow Battery Charging: Understand Electrochemistry

    I am researching the electrochemistry of redox flow batteries, however, I do not understand the charging process. As I understand DC current arrives in an electrode and transfers energy to excite electrons in the electrolyte thus providing energy to trigger a chemical reaction (storing...
  43. A

    Need formulas for the dis/charge of batteries

    Been asked to write a four page introduction to an Extended Experimental Investigation. The topic is investigating the discharge rate of batteries as a function of temperature. Need some help [Thread moved to the schoolwork forums by the Mentors]
  44. patric44

    Kirchhoff's law problem with two batteries

    the question is find the value of E1 that would make the ammeter reading = 0 ? i tried KCL , and KVL and got the following equations : ( I1 belongs to 3 ohm , I2 belongs to 2 ohm , I3 belongs to 4 ohm ): I3 = I1+I2 E1 = 3I1 + 4I3 12 = 2I2 + 4I3 but now i have 3 equations in 4 variables ?! i...
  45. Tesla1963

    I How does high level radiation affect lead acid batteries?

    During episode 2 of the HBO miniseries “Chernobyl”, the search lights held by the three technicians entering the area beneath the reactor eventually go out from exposure to radiation. If the search lights were powered by lead acid batteries, how does radiation interfere with and/or hasten the...
  46. BluJay214

    Circuit confusion, light bulbs, switches, and batteries

    Before I modeled it, I thought the current would move in a figure 8 due to the battery on the right still loading the current. Then I thought of how the battery on the left would counteract that current. I am still not sure what is going on here. Is it kind of like a short circuit where the...
  47. T

    Using a generator to charge 2 batteries

    My project is to create a circuit for a stroller that can store the mechanical work into electrical while moving around and with the push of a switch, use the electrically stored energy to assist the movement of the stroller. I’ve tried capacitors but it ended up not being enough voltage and I...
  48. P

    Would a charged lithium battery combust more energetically?

    Conceptually this question makes sense to me I know a overcharged lithium battery will became unstable however with identical batteries except a different level of charge what would the properties of their combustion be? In depth conceptual, and mechanical explanations are always appreciated as...