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.
Homework Statement
For an ideal battery (r = 0 Ω) closing the switch in the figure below does not affect the brightness of bulb A. In practice, bulb A dims just a little when the switch closes. To see why, assume that the 1.5 V battery has an internal resistance r = 0.44Ω and that the...
Homework Statement
I'm working my way through MIT 8.02x, the intro E&M course, on EdX. In Homework 3/Problem 3, we insert a dielectric between plates in a capacitor that is connected to a battery supplying potential V. So the charge on the capacitor increases by Q. How much work is done by...
How can current source be implemented? I think the source of current is the battery itself (due to potential difference). Plus current source has its own symbol. If battery is the source of current then does current source refer to the battery?
Say you have to power a simple motor with a solar panel, but that panel does not always supply the necessary power. What is the simplest circuit that could combine a DC motor, Solar panel and battery backup to ensure that the motor will continue running even when the solar panel cannot supply power?
1) I don't understand why current flows, for example when you have a source, it has 2 poles, + and -: then the electron should go towards +, if it's in the position 'D', it should just be stuck -- my theory is that because the electron that's in 'A' "enters the battery", so the battery has...
Trying to get my head around some ideas about "rechargeable" batteries and getting in a muddle!
So I get the idea that rechargeable is a rubbish word for them but I have 2 questions:
1) Does heat loss (i.e. from bulbs) in a DC circuit result in eventual lower PD across a cell? Thinking in...
I have an older Win 7 laptop that I put it away for 2 months. I power it up lately, few things gone wrong. The computer said my battery died and have 0 charge even though I have it plugged in for over a day. Whenever I unplug the power, the computer just shut down completely.
It's very hard...
I am planning to use the Panasonic NCR-18650 cylindrical cells for a BEV (Battery Electrical Vehicle). As it would be easier to buy ready-made modules, I have found a supplier selling a Li-ion pack that delivers 417 Wh(or in other words 11.6 Ah) at 36 V (something like what this guy uses...
Hello
I need a source to power ADSL router when the electric power would be cut for any reason because i need to keep my laptop that i use for work connected to the internet.
I found this "Anker® 2nd Gen Astro Pro2 20000mAh 4-Port Aluminum Portable External Battery Charger with 9V/12V...
Hi guys,
I'm Chris from Germany. First of all, I'm not an expert in science, biology or electrical engineering. But i would have this question to experts, that's why I'm here. Sorry if my question will sound "dumb" or "easy" but as i said, i don't have any knowledge in this field.
Is it...
Homework Statement
Why is the formula for internal resistance for a charging battery v = e + Ir?
When the battery is supplying I to the circuit I understand why the terminal voltage, V, equals emf - IR (voltage lost by internal resistance), but if a battery is charging, why is the...
I don't understant how the positive electrode can attract both electrons and the positive Li ions as they both flow to it. Also, the way to start the whole process is to let the electrons flow, right? (Close the circuit.) Without it, the ions also don't want to start flowing, although there is...
So I am in the process of building various solenoids for some projects I have. But the issue I have is that the battery I use is over heating. From my understanding, when I connect a circuit to a battery, the energy gets dumped very quickly and overheats the cell. Is there a way to calculate how...
Hi every one,
I placed a multimeter probe across the terminals of a 1.5 v alkaline battery and saw 2 M Ohms, I did the same across a mV power supply at 1.5 volts and got little below 1.5 K ohms. I don't understand what makes them have diffrent resistance, and exactly why?
I did this because I...
Hi guys,
I am working on a school project. I have an inclined cart mounted on rails moved by a winch. I would like to install an alternator on one of the cart axis, so I can charge a 12V car battery - 20Ah. The wheel turns at 12 RPM. At that speed the alternator will not work, so I am also...
We have a battery operated chair lift for seniors at our church. I am looking to replace the on board batteries with a DC power supply. The unit has 2 small 12 volt batteries in series to provide 24Vdc to power the chair. The motor is a 24Vdc 4 amp motor. I had put in a 24Vdc 200 watt power...
In the Princeton Review Cracking the AP Physics C Exam 2011 Edition book on example 11.9's solution, one of the batteries' terminals are swapped (the battery with 10V). I am not sure why the author's do this considering the current is drawn the same. Later on in the solution, they recognize...
Hello everyone! I'm working on my practical project in college and it's roughly about ''air battery'' (CAES) which is filled with help of solar cell (eventually I need to build small version of it).
My mentor explained it to me roughly as well and I would love some help as I'm not very good at...
What happens if a battery cannot supply enough current?
Let's say we're using a 10V battery capable of supplying 1A of current.
A single resistor is then connected so that the current is flowing through it.
Using V=IR, if the resistance is 10 Ohms, current is 1A.
What if the...
Hi I need a circuit to charge 4 aa lithium ion batteries. I need it to charge at 5 volts and when the batteries are done charging, the circuit cuts off. It would help a lot if I could get this in a small space around 2 quarter's. Thank You.
So supposedly if you leave your phone plugged into a charger but the charger is not pluged into anything then it will discharge your phone faster, so if the charger cases have a charger connector constantly in your phone will it actually discharge it?
Dear Friends
Is there a good battery capacity measurement device you can recommend?
I need to measure how much capacity a lithium pack really has.
Thanks.
regards
Ramone
Hi..
I am working as a signalling engineer in Railways. This weekend i am going to give a presentation on super capacitors and their use in railway systems. Most importantly i am going to show how we can replace batteries with super capacitors (EDLC). The problem i am facing is i don't have any...
Homework Statement
Two parallel plates, each having area A = 3558 cm2 are connected to the terminals of a battery of voltage Vb = 6 V as shown. The plates are separated by a distance d = 0.54 cm.
1) What is Q the charge on the top plate? 3.5*10^-9 C
2) What is U, the energy stored in...
My question is simple: Why do batteries need electrolytes? Wouldn't the battery need the charge to flow only through the circuit in the device being powered? The point of the anode and cathode's separation is to preserve the potential difference, so why allow charge to flow through an electrolyte?
There is an amount of energy stored in the battery. However, the rate of output would depend on
the system its powering. What is the best formula to calculate the output energy from a battery?
Also, what formula would calculate the stored energy of the battery?
Does a dead 1.2V rechargeable AA NiCad battery act as an open or closed circuit?
My electric toothbrush's rechargeable battery recently died and the manufacturer expects me to replace the entire unit. Personally, I think that's a waste of money so I've already opened it up and I can see the...
Circuit Analysis -- Resistors and a battery
Homework Statement
Hello, if you see the attached I am trying to find the current I4.My plan was to find Voltage across R4 and use Ohm's law.
Homework Equations
V=IR
The Attempt at a Solution
I have simplified the circuit down(attached pic), I...
There is this voltage source that generates different types(piezoelectric device, the pressures exerted are not the same everytime), it is not a sine wave properly(A), then passing it to a full bridge rectifier, the outcome is like B, then you use a smoothing capacitor and the outcome is like C...
http://i.imgur.com/qsZ0PM4.jpg
I opened up the back of the calculator to see what kind of battery I might have to replace eventually, but I didn't expect to see a second battery slot. Is it a backup battery slot? If so, how do I tell what kind of battery fits in there? I checked the manual...
NEVER MIND! I realized my question is kind of stupid. Its night here and I am kind of sleepy. :))
Homework Statement
a battery of 4V is connected opposite to a battery of 2V to charge the 2V battery. assume the current running through the circuit to be 2 Ampere. What is the Work done by
1)...
Hello PF,
Homework Statement
The capacitor C_1 is connected to a battery as shown. After being charged, it is connected to the capacitor C_2 and the second battery as shown. When all the charges come to rest, what will be the charge on capacitor C_2?
http://imgur.com/4ciJRrn
Homework...
I collect branded goods and came across this old Energiser battery which had been left at one of those communal recycle collection points in our local supermarket, what a find, it's the old ones that I remember from my childhood and labelled as "Made in Britain" (my God, that must have been some...
When a batter is charging, let's say 3V battery.. when it's full, does it stops there or continues to take in charge? Like for example, capacitors charges up, until it reaches the voltage which was charging it, when both becomes equal, the cap becomes open circuit.. i wonder if batteries also do...
What is the funda behind the Elemental Composition Calculation of Cathode Material for Sodium / Lithium Ion Battery (Na2/3 Ni0.4 Mn0.4 Co0.2 O2)/ AMO2? Apart from the Oxidation state calculation, Phase Diagram Elimination of mixtures and Random Compistion, is there any Principle behind it?
Homework Statement
There are two alike initially uncharged spheres of radius r at a distance of d>>r, as shown in the figure.
a) Switch ##K_2## is closed. What is the force exerted between the two spheres?
b) What would be the force between the two spheres, if in the previous experiment...
So as I am junior high school student just learned that when the terminals of wire are connected to a battery,an E (electric field) is established inside the battery from positive to negative end/terminal (How did I assumed one as positive and one as negative? COnvention regarding electric...
When we place a voltmeter across a single battery which is connected to another battery in series, does voltmeter show the emf of the single battery or the sum of emf of both the batteries?
I was watching this video: http://www.youtube.com/watch?v=P8A1U-RZDao&index=7&list=PLLUpvzaZLf3Jv7AjU5pfY8s25-QBCfdIZ
and at around 6 minutes, I got confused. Ill summarize it below in case the link does not work:
If you have a circuit which consists of a battery which is 12 volts, and a...
I've read about why it would be nearly impossible for an individual to construct a working home built nuclear reactor (of any variety), but I've never understood why a home built nuclear battery couldn't be constructed (think Henry Moseley's work). The size and power output would be impractical...
Does say a 1.5 volt voltage in a battery mean the change in electric potential as one electron goes from the negative terminus to the positive terminus? Does a larger voltage battery simply mean more kinetic energy through the load (hence more friction/heat)? Or does it have to do with...