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. M

    Solved: Power & Batteries Calc: Resistance, Factor Increase

    Homework Statement An Ordinary flashlight uses two D-cell 1.5V batteries connected in series. The bulb draws 450mA when turned on. A)Calculate the resistance of the bulb and the power dissipated. B) By what factor would the power increase if 4 D-cell batteries in series were used with the same...
  2. W

    Charging lithium ion batteries

    I have a couple of different lithium ion battery packs. On one pack charging current reads 0.1 amps, and on the other 1.5 amps. I already charged the 0.1 amp pack with 0.1 amps, and seems to be working. Now, I'm sort of weary charging the other pack with 1.5 amps. Doesn't that seem too much...
  3. A

    9v Batteries Powering Multiple Items

    I'll start with the typical "I'm new to this and don't know much about DC wiring and power." I'm trying to wire 10 flickering candles that each run on a single 9v battery into a fake cake and do so in a manner that will make pulling the batteries out quick and easy without having to remove each...
  4. K

    Batteries in parallel instead of series

    Say I have three different circuits, each with three 9V batteries: CIRCUIT ONE Parallel 9v Battery 1 -> Coil 1 -> 9v Battery 1 9v Battery 2 -> Coil 1 -> 9v Battery 2 9v Battery 3 -> Coil 1 -> 9v Battery 3 CIRCUIT TWO Parallel 9v Battery 1 -> Coil 2 -> 9v Battery 2 9v Battery 2 -> Coil 2 ->...
  5. ZapperZ

    U.S. DOT Bans Transport of Spare Lithium Batteries in Checked Baggage

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  6. J

    Life of batteries (Probability)

    Homework Statement The lifetime of batteries are independent random variables Xi, i= 1,2,... each having exponential distribution given by the density f(x) = 2e^-2x, x>0, 0 elsewhere. If a flashlight needs two batteries to work, then the time that the flashlight can operate is a random...
  7. B

    Running 24V on two 12V batteries

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  8. M

    Solar Panel to Recharge Hybrid batteries?

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  9. M

    Circuit with 2 batteries is confusing me

    Homework Statement The circuit in the figure is composed of two batteries (E1 = 6 V and E2 = 4 V) and three resistors (R1 = 4 , R2 = 4 , R3 = 5 ) as shown. (a) What is the current I3 flowing through the batteries? I3 = .286A (no problem here) (b) What is the voltage Vb - Va...
  10. R

    Water can burn when 'charged up' with batteries?

    i found this online, he puts two batteries in a glass of water for 30 minutes, then removes the batteries, and the water lights with a flame. Its been favorited by 6000 people so it seems to be popular. How does that work? i presume that its a type of electrolysis? EDIT: DOES NOT WORK!
  11. O

    Batteries connected in parallel and resistance

    Homework Statement What i may ask may seem simple, but it is casuing me a lot of headaches. What is the effective potential difference across a resistor if it is connected to a parrallel connection of batteries. Let's quantify the variables. Battery one has an e.m.f. of 2 V while battery 2 has...
  12. X

    A toy car has a mass of 120g, including two 1.5V batteries connected in series.

    A toy car has a mass of 120g, including two 1.5V batteries connected in series. Suppose the motor that drives the car is 80% efficient (i.e., 80% of the electric energy goes to the drive wheels, 20% is dissipated as heat) and that friction and air resistance are negligible. How much charge...
  13. A

    Radionuclides instead of batteries?

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  14. L

    Increase UPS run-time with bigger batteries?

    i have two UPS's that protect my computers and entertainment system. I'm at less than half the kva rating of each of the UPS's but the runtime is too low for my liking. they both run with 4 qty 6V sealed lead acid batteries. my question is: can i simply use higher AH capacity batteries...
  15. D

    Question involving voltage and galvanic batteries

    I'm currently studying for the MCAT and most of the physics questions I get wrong, the explanations adequately help me. But, one question has me stumped. "Question:" What is the standard emf for the galvanic cell in which the following overall reaction occurs? 2Na(s) + Cl2(g) ->...
  16. K

    Liquid Batteries: What are They?

    hi can anyone tell me the concept of liquid batteries.
  17. H

    A question about laptop batteries

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  18. Danger

    Remote Control Airbus Plane - Fun Mansion

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  19. M

    Purpose of batteries and dynamos

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  20. J

    High voltage batteries, not 2V per cell

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  21. A

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  22. I

    Battery Size: 1.5V batteries

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  23. P

    Solve Battery Parallel Problem: Get Help Now

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  24. F

    Do 3023 batteries exist? (not CR ones)

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  25. S

    Motor & Battery: 12V 3.5A/hr Support 120V 4.7A Motor?

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  26. N

    Watts - How Does Voltage Affect Batteries and Static Electricity?

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  27. A

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  28. V

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  29. wolram

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  30. R

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  31. DaveC426913

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  32. DaveC426913

    Watch batteries packaged in inert gas?

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  33. E

    Running 1500W off car batteries

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  34. M

    Parallel Batteries: Power a Wheelchair Motor

    Problem: "Two automobile batteries are connected in parallel to power a wheelchair. If each of the batteries has an emf = 12.0 V and internal resistance r = .020 ohms, and the wheelchair motor has a resistance R = 1.00 Ohms, find the current provided to the motor. What would be the current...
  35. Mk

    Calculators My calculator batteries are out.

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  36. D

    Help with dielectrics, capacitors, batteries, etc

    1. can someone please explain the idea of a dielectric to me (or at least give me a link that explains it in laymans terms) - all i understand is that its placed between two capacitors and it increases their capacitance (by the factor of K). what does it do to the voltage? and the charge...
  37. J

    I Just Picked Up Some Zinc-Carbon Batteries - What Now?

    Hi, I didn't know they still made these anymore, but I just picked up a few zinc-carbon batteries from the corner store (not knowing they were zinc-carbon - I just bought them because they were three times cheaper than the other ones :rolleyes: ). Correct me if I'm mistaken but the anode...
  38. W

    Flow Batteries: Australia & Japan Pioneers

    Do a google on " flow battery " this woman from Austrailia did some recent work with them ,really interesting stuff.. in Japan they use them to supply Grid Power from a windfarm ..
  39. K

    Comparing Lead-acid and Nickel-Cadmium Batteries

    Hi:smile: , How are you? I am a student in Academy for aviation. I study now Electrical book for avionics, I have confuse about Lead-acid battery and Nickel-Cadmium battery. I want to know what diffenet between them. Thanks I appreciate it:rolleyes: .
  40. B

    Can resistance wire and batteries be used to create a self-heating bottle?

    hello, one of my projects is to develop some sort of self heating bottle. i must fabricate and build a working prototype. i have a couple of ideas. one is to use the same concept as a toaster. wrap the bottle in nichrome, a type of resistance wire. however, would the wire get hot enough to heat...
  41. cepheid

    Connecting Different Batteries in Parallel: What Happens?

    Stupid question time. What happens if batteries of different voltages are connected in parallel? I know, in circuit theory class, you just don't do that, because it doesn't make sense, but what happens if you actually DO it in real life?
  42. L

    Understanding Closed Circuits & Batteries

    Why the circuit must be closed to let the batteries send out electrons? If the circuit is opened, why do the batteries stop sending out electrons?
  43. I

    Exploring the Dangers and Limits of Batteries: A Deeper Look at Ohm's Law

    Hello, I am just starting to teach myself about electronics, and am already coming up with questions my text is not answering adequately. Unfortunately I don't know anyone who I could ask as I'm not in school. Consider two 12V batteries, say a car battery and a garage door opener battery...
  44. Orion1

    Question: Where Can I Find Affordable Rechargeable Batteries Online?

    What are the best and most cost effective rechargeable 'AA' and 'D' batteries on the internet in the United States? :confused:
  45. D

    Lead Acid Batteries: Mixing Old/New Cells- Damage?

    Can mixing (in series) old cells with new cells of the same voltage and rating damage the new cell? If so why? The cells are recharable.
  46. S

    Researching the Potential of Nano Batteries: Seeking Forum Insight

    Hope this is the correct forum for this... :uhh: I ran across this today. I've begun researching what companies are doing to replace our current dry cell batteries used in electronic devices. This is the first reference I've seen of a so called nano battery. Anyone with experience here...
  47. M

    Nuclear Batteries: Engineers Converting Radioactive Decay to Power

    If they figure out how to manufacture them efficiently, we might see nuclear powered batteries in a few years. It seems from this article that engineers were finally able to convert radioactive decay into a useful form of power...
  48. V

    Difficulty with Parallel Batteries

    Hi everyone, I've tried searching over and over again in my textbook and online, but I can't seem to find anything about the specific nature of parallel batteries. So I have the following problem that I can't get anywhere with: There is a 6 ohms light bulb connected to two 1.5 V...
  49. M

    Dc circuits with two or more batteries

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  50. T

    Power of D-Cell Batteries: Calculate & Understand Benefits/Risks

    Hi, I have a pretty straightforward problem that I am screwing up on for unknown reasons. Basically, it's about two D-cell 1.5-V babtteries connected in series. The give the current and you calculate the resistance and power -- simple enough. But then they ask by what factor would the...
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