Batteries Definition and 464 Threads

  1. S

    Capacitors will never rival batteries?

    What is fundamental physical constraint which doesn't allow the best (super)capacitors rival the best batteries in energy density? Or it could change someday?
  2. P

    Kirchhoff's Rules. Solving for currents in circuit with two batteries

    Homework Statement What are the sizes and directions of the currents through resistors (a) R2 and (b) R3 in Fig. 27-42, where each of the three resistances is 4.0 Ω? Homework Equations ΔV=IR The Attempt at a Solution Equations: 1) ΔVB2 -(i1)R1 -(i2)R2 -ΔVB1=0 5V - 4(i1)...
  3. T

    Using humans as batteries: is this movie quote accurate?

    Hi there I have just re-watched The Matrix (great movie) and one quote really stuck out to me: "The human body generates more bio-electricity than a 120-volt battery and over 25,000 B.T.U.'s of body heat. We are, as an energy source, easily renewable and completely recyclable, the dead...
  4. G

    Questions about batteries and electric motors

    a concept i can't grasp is the meaning of voltage for an electric motor. it seems all the motor needs to operate is a magnetic field which is generated by current. why does the electric motor "care" whether the current is fed to it from a 100V or a 200V battery? Isn't the concept of voltage...
  5. J

    Current, Voltage and Batteries

    I have a bit of confusion over how a bulb lights up in a simple DC circuit. My book says it's because the electrons within the filament start moving as soon as a battery is connected. My book also says that voltage is the potential energy an electron has. It says it gains this energy as it moves...
  6. C

    Can electric shaver charge batteries installed with reversed polarity?

    Hi, I bought 2-AA (with pins tabs) rechargeable batteries for a Braun electric shaver. Checked the polarity of the old batteries, marked it on the board, and soldered the new batteries accordingly. (In series.) First charge lasted 4 weeks. Next 3-4 charges lasted less and less. Now...
  7. Q_Goest

    Why don't electrons flow between batteries when not connected?

    Let's say you have 2 batteries, both 1.5 V. If you put your red voltmeter lead on the + of one battery and your black voltmeter lead on the - of the other battery, and assuming the two batteries are not touching, the voltage you read is zero. I know this is a simple question, but why? Why don't...
  8. P

    Multi-loop RC circuit, 2 batteries, 7 resistors, 1 capacitor

    Homework Statement For the multi-loop circuit as shown, assuming the capacitor is initially uncharged, find the currents in each of the resistors at t=0 after the switches are closed. So I believe there are 8 unknowns really because of the 8th branch with the capacitor. If you look at the...
  9. T

    Direction of Electron Flow with Real Batteries

    Hello all - a quick question that I can't seem to find an answer to online that I trust... While the conventional current model describes flow of positive charges around a circuit, we know that current is actually the flow of electrons (at least in common metallic conductors). Which leads to...
  10. P

    Are nuclear batteries possible?

    is it possible to make a nuclear "battery" which works off nuclear not electrochemical reactions using berylium/graphite shielding?
  11. P

    Getting high current from AA batteries

    I am trying to increase the strength of my electromagnet, at the moment by increasing the amperage. I have been using an old 12V motorcycle battery, but also tried with 10 AA batteries. I was wondering how I could connect the AA batteries to get a high current, so hopefully a stronger...
  12. A

    How To Determine Series & Parallel Connections With Multiple Batteries

    how to determine series and parallel connections in a resistors when multiple batteries are used?
  13. B

    Two Batteries In Series-Total EMF and Internal Resistance

    Two Batteries In Series--Total EMF and Internal Resistance Homework Statement Two 1.50-V batteries—with their positive terminals in the same direction—are inserted in series into the barrel of a flashlight. One battery has an internal resistance of 0.260 Ω, the other an internal resistance of...
  14. R

    Series Circuit with two batteries

    Homework Statement A. Make a prediction about the direction of current flow through each resistor. (6 points) B. What current flows through each resistor? (15 points) C. What is the voltage drop across R2? (4 points)Homework Equations Req=R1+R2+R3The Attempt at a Solution I'm sort of lost as to...
  15. F

    Batteries: capacity, charging and discharing rate meaning

    Hello Forum, Battery chargers are devices to put energy into a secondary (rechargable) bttery by forcing an electric current through it. The charge current depends on the technology and capacity of the battery being charged. The capacity of a battery represent the amount of electric charge...
  16. D

    Can I Connect 37V and 12V Batteries?

    I have a question that may seem odd, but I am really searching for an answer. I have several 37 volt lithium ion bicycle batteries that hold a lot of charge after being recharged through grid outlets. I also have an old RV that uses 12 volt appliances run from 12 volt lead acid...
  17. J

    Circuit with two batteries and three resistors - Find current

    Homework Statement Find the current through R1, R2, and R3 for the attached diagram. Homework Equations Ohm's Law V=IR I=V/R etc.
  18. T

    Finding terminal voltage given two batteries

    Homework Statement http://www.webassign.net/giancoli5/19_31alt.gif I was given this circuit and told that R=6.6Ω. Based on the information, I was asked to find the terminal voltage. Homework Equations Terminal V=Emf-ir Kirchoff's laws The Attempt at a Solution I used Kirchoff's...
  19. OmCheeto

    Understanding Batteries: Exploring Lead Acid Reactions

    I used to think I knew how batteries worked, but I've decided that if I did, I now don't. Being that chemistry is one of my worst subjects, I decided to evade all of the anion, cation, this, that, and other terminology that I find incomprehensible and totally unable to devote to memory. So...
  20. K

    Simple circuits and the direction of batteries

    When constructing a simple circuit with a battery, bulb and a switch, the placement of the battery is unimportant (I can hook up the battery + then - or - then +). So why is it that so many battery powered electronic devices only work if the batteries are inserted in a specific direction?
  21. F

    How does putting batteries in series increase voltage?

    Homework Statement When you put batteries you place the negative terminals to the positive which supposedly "bumps' each electron to the next battery. However, the positive terminal is positive enough to neutralize the negative terminal and vice versa. Therefore, when I place batteries in...
  22. L

    Circuit help - resistors and batteries in a network

    circuit help -- resistors and batteries in a network Homework Statement (a) Calculate the current through each ideal battery in Fig. 28-41. (As a sign convention, assume the currents are "up" through each battery.) A (I1) A (I2) A (I3) Assume that R1 = 1.5 , R2 = 2.5 ...
  23. J

    Experiment about Discharging Batteries

    Right now I'm doing an experiment for my EE about battery capacity. How would I be able to monitor the battery's true emf while discharging the battery at a constant current? Also, when I connect the battery in a circuit and discharge it at a constant current, I notice that the voltage across...
  24. R

    Circuit with 2 batteries and 6 resistors

    Homework Statement A circuit is constructed with six resistors and two batteries as shown. The battery voltages are V1 = 18 V and V2 = 12 V. The positive terminals are indicated with a + sign, The values for the resistors are: R1 = R5 = 73 Ω, R2 = R6 = 121 Ω R3 = 62 Ω, and R4 = 92 Ω. The...
  25. R

    Circuit with 2 Batteries and 6 Resistors

    Homework Statement [/B] A circuit is constructed with six resistors and two batteries as shown. The battery voltages are V1 = 18 V and V2 = 12 V. The positive terminals are indicated with a + sign, The values for the resistors are: R1 = R5 = 73 Ω, R2 = R6 = 121 Ω R3 = 62 Ω, and R4 = 92 Ω...
  26. G

    Circuit with Two Batteries and Six Resistors

    Homework Statement A circuit is constructed with six resistors and two batteries as shown. The battery voltages are V1 = 18.0 V and V2 = 12.0 V. The positive terminals are indicated with a + sign, The values for the resistors are: R1 = R5 = 64.0 Ω, R2 = R6 = 157.0 Ω R3 = 53.0 Ω, and R4 = 65.0...
  27. S

    Could capacitors ever rival best batteries?

    If I understand it correct,energy of atomic electronic shells fusion cannot exceed energy of their breakdown.For example you need to spend more energy to break down water molecule than you receive energy when you burn hydrogen.Does that mean that energy stored in capacitors could potentially...
  28. A

    Charging an super/ultracapacitor from AAA batteries

    I know that AAA batteries (and batteries in general) provide a very low continuous current due to the chemical reaction. Is it feasible to charge a capacitor of say 25F (yes F not μF) from AAA lithium batteries...
  29. J

    Two Loops, Two Batteries: Find the Currents

    Homework Statement Question: Find the current in the circuit shown. http://i1307.photobucket.com/albums/s599/JustOn4Fun/PhysicsFigure_zps39d4c66d.png Homework Equations Not sure if equations are necessary since it's a question testing the use of the following rules: Junction Rule The...
  30. J

    Experiment about Discharging Batteries

    I am trying to find the capacity of a AAA battery by discharging it. How would I be able to discharge the battery at a 1A current so that I don't have to wait for a long period of time?
  31. T

    Some questions of voltage, charge, and batteries. Thanks.

    Hello everyone, I know electronics pretty well. I'm pretty good with that, but my physics and chemistry understanding of what is going on is a little weak. I'm trying to do a good Youtube video on Ohm's law and I want to have a solid foundation to my understanding. Not just V = IR, but...
  32. C

    A question regarding batteries

    Hi if you have a galvanic cell, with Zink at the anode and Cu at the catode, which force then makes Zn electrons go to the cobber catode?
  33. R

    Are lithium-ion batteries the future of electric aviation?

    Hi all. I was wondering, are lithium-ion batteries the best type of batteries for electric vehicles? I also remember watching a video of Elon Musk (from Tesla Motors and SpaceX) claiming that lithium-ion batteries are increasing their energy density by 8 to 9 percent every year. I googled...
  34. S

    Li-Ion Battery Swelling: Causes and Solutions

    Does anyone have any experience of the swelling of lithium-ion battery packs? Attached are photos of one that came into the workshop recently. The first is still in its Macbook and is genuine Apple, although you can see how it has forced its way out and distorted the case. The second...
  35. B

    How do batteries work? (DON'T MAKE IT SIMPLE)

    First off, this isn't really a homework question, but I'd rather post it here and look like somebody trying to learn rather than being mocked at secretly in the engineering section. So my question is, how do batteries work, SPECIFICALLY? Down to the ditty-bit details. Every source I try to pop...
  36. G

    Using a wall wart to replace batteries

    I have this dc heli called protocol. It charges from the remote which uses 6 aa batteries. So I got a 9 V wall wart. There's a couple problems with the wallwart when I used my analog multimeter to read the voltage it was reading 60 V. When I measured the batteries in the remote ball the remote...
  37. C

    Parallel Batteries and their effect on Current.

    Hello, I would like to know how you can calculate the current in a circuit with cells in parallel. When searching for this on the web all I get is current in parallel circuits, and not my specific question about cells in parallel. If there is maybe an equation, method, or link somebody could...
  38. B

    Compute the total power delivered to the circuit by two batteries

    Homework Statement http://tinypic.com/r/e8v1ad/6 ^^ that is a photo of the circuit Homework Equations P = I*V , but i don't understand how to do it with two loops and two batteries like in this photo. The Attempt at a Solution I have calculated I1 to be .9, I 2 to be .15 and...
  39. R

    Voltage ratings of Li-Ion batteries

    Dear Experts I bought a lithium-ion battery rated at 3.7v. I charge it with my existing phone charger rated for 3.7v batteries and charging at 4.2V. i like to know why are batteries are rated like this. That is, a 3.7V rated battery is actually charged to 4.1 or 4.2 when its considered...
  40. S

    Batteries in Series: Troubleshooting No Activity

    Hello, I can't image what is the exact path of electrons in two or more batteries conncted in series... if electrodes are immersed into the electrolytes and chemical reactions should continously happen why the circuit in the picture down here has no activity ?
  41. J

    How Do Carbon Nanotube Batteries Store More Energy?

    Can someone explain how carbon nanotube batteries work? They are carbon nanotubes put on a layer then and covered in an electrolyte such as lithium. These batteries are able to hold 5 times more electricity than a conventional battery. I looked up batteries using carbon and not carbon...
  42. D

    US Source for Lithium Iron batteries

    Does anyone out there know of a US based source or distributor for high capacity lithium batteries? 100Ah, 200Ah? 3 - 3.2 volts Everything I am finding is China, and the shipping is just outrageous. Thanks, pud
  43. 1

    Potential applied across two points with batteries

    Homework Statement attached Homework Equations The Attempt at a Solution The first two were pretty simple, but I'm having trouble grasping why my guess for #3 was actually correct. Why are we ignoring the parallel battery/resistor combo up top and just adding the voltages of the...
  44. F

    More energy in bullets or batteries

    Are there more joules in a bullet or a battery (in it's lifetime). I'm afraid I don't know bullet calibres but we can assume that we're talking about an AA Battery.
  45. N

    Damaging lithium ion batteries

    So I have learned that all batteries have an internal resistance which will limit the current that it can output, so that you can't discharge a huge battery in a split second because of that internal resistance. But what I am wondering is, at what point is it dangerous to draw too much current...
  46. W

    Kirchoff's Equation w/ 2 Batteries and 4 resistors

    Homework Statement The circuit in the figure is composed of two batteries (ε1 = 9.0 V and ε2 = 5.0 V) and four resistors (R1 = 110.0 Ω, R2 = 40.0 Ω, R3 = 30.0 Ω, and R4 = 50.0 Ω) as shown. 1). What is the current I1 which flows through R1? 2). What is the current I3 which flows through R3...
  47. A

    Very simple circuit of 2 batteries

    I have some trouble understanding the equations that you get from Kirchoffs law when there are several batteries in a circuit. Consider a circuit with two batteries like the attached. Kirchoffs laws just gives ohms law for the two circuits as were they completely independent: U1 = RI1 U2 =...
  48. J

    How many batteries can run in series

    I live off the grid and am looking to upgrade my battery bank. I now have 12 6v batteries. 4 are ran in parallel to make a 24v system. The rest are run in series to increase watt hours. is there a maximum amount of batteries I can run in a series?
  49. R

    How Much Energy Can Pedaling Generate for Rechargeable Batteries?

    Hello! this is my first post here,hope it's the good part of the forum. I have some questions and i would appreciate it very much if someone more knowledgeable than me could help me out. A while ago I saw a radio that was used without batteries,you had a wheel and you just had to spin it...
  50. P

    Does volts and amps get at half while charging multiple batteries?

    Hi guys (and gals) Say, i have a solar panel rated at 100w 12v with the following specs: Short circult current(Isc): 6.01A Open circuit voltage(Voc): 21.5V Optimum operating current: (Imp) 5.52A Optimum operating voltage: (Vmp) 17.78v Maximum power: (Pmax) 100W And I decide to...
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