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.
I am using a buck converter with a battery pack, for a usb charger. The issue is, is that the buck converter I have ( http://www.ebay.com/itm/DC-Converter-Step-Down-Buck-Module-7V-24V-to-5V-3A-5V-usb-output-power-adapt-/261030150117?hash=item3cc69bffe5:g:Q3UAAMXQTT9R0Qos ) has a led on it, which...
Homework Statement
There is a battery producing emf V and the current around the circuit is I. The battery has an internal resistance of R. What is the power transformed by the battery
Homework Equations
P = VI
P= I2R
The Attempt at a Solution
Maybe P=VI+I2R because there is some electrical...
Hello everyone,
How much of a safety hazard is it to store a car battery inside a classroom/lab? It's a new battery and it is plugged into a charger all the time. I use is only couple of times per year for a demonstration. Thanks!
-Gamma
Homework Statement
Will current flow in an ideal circuit given that there is only an ideal battery in the circuit?
Homework Equations
V=IR
The Attempt at a Solution
Since there is no resistance through out the circuit no potential is dropped so no current flows
hi all,
i am embarking on a new project, building a outdoor rolling credenza that has TV (with air operated TV lift), cd player, small receiver, 100% wireless (power and wifi, etc).
my design calls for a battery pack that can deliver approx 5x106 joules, this leaves me in the ballpark of...
Homework Statement
Find the current through and power dissipated by each resistor
Homework Equations
V=I/R
ΣIin=∑Iout
The Attempt at a Solution
Did I set up the loop laws correctly and where do I go from here?
Homework Statement
When a certain 9.0V battery is connected to a voltmeter, the voltmeter reads 8.00V (assume that the voltmeter has an internal resistance of 10MΩ. We may conclude that
(A) only 1/9 of the battery's fuel has been used, and so the battery has plenty of life left in it.
(B) the...
Homework Statement
A real battery can be modeled as an ideal voltage source in series with a resistor. A voltmeter with input resistance of ##1000\Omega## measures the voltage of a 1.5V worn out battery as 0.9V. What is the internal resistance of the battery.
Homework Equations
##V=IR##
The...
I'm in charge of designing a battery bank (using 18650 batteries) that will produce large amounts of heat for a short period of time. The battery bank will be in a near vacuum (~800 Pa), so convective heat transfer will not be effective. Since the operation time is only ~80 seconds, my thought...
I live in an rv. My power comes from solar and ocassional boost from my generator. I have 3600wh in battery power.
But i know its really bad for my batteries to draw lot of power fast.
So i would like to create a capacitor bank that would stay charged.
Ive done some calculations but not...
Hi all,
For some reason I'm really struggling to understand how batteries store energy and how this relates to electric potential.
Can I just think of a battery as two separate plates one accumulating positive charges the other negative. The positive and negative charges are attracted but they...
I conducted an experiment to find out the emf of a battery, the result turned out to be 1.35 volts , however on the battery, it says the battery is 1.5 voltage.
Does it mean that my method is wrong or less accurate. But I used three different methods:1) measuring the terminal voltage across...
Hello PF,
I am a middle school teacher in Humboldt county, CA and teach physical science to eighth graders. We are beginning our electricity and magnetism unit and have students have experimented with making a light bulb illuminate using a battery and copper wire. My question is, if we make a...
Homework Statement
[/B]
Three resistors are connected to a real battery. The open circuit voltage of the battery is 4.5 Volts. The voltage across the 5 Ohm resistor is 2.5 Volts.
A) What is the voltage across battery terminals?
B) What is the internal resistance of the battery?
Here's a...
Homework Statement
The problem includes a graph. All I have is a current to external resistance graph, with 20 A coming at 10R of external resistance. I am to find the EMF and internal resistance of the battery.
Here is the problem and my two attempts.
http://1drv.ms/1LKbu5H
Homework...
So I want to charge a battery from a pedal-powered dynamo, and use that to power my PC, my screen, and pretty much everything else in my home office.
This whole thing is a little project to improve my own health while I'm working; I'm not here expecting to make major miracle savings on the...
Homework Statement
Three resistors are connected in series to a battery. The resistances are R1 = 15 Ω ,R2 = 25 Ω , and R3 = 30 Ω and the current through the 15-Ω, resistor is 2.7 A .
What is the potential difference across the battery terminals if the battery is ideal?
What is the potential...
Hi, I am working on a piezoelectric energy harvesting project. i was able to use my piezoelectric to charge up my AA NI MH battery 1300mAH from 0.93V to 1.201V. However, once i removed the battery from the battery holder, the cell voltage starts to drop without being connected to any load...
Hello there everybody
In my research group we've been working on PV cells and exploring non-conventional techniques to try and raise the efficiency of some of the lesser explored materials that have PV potential.
Well, last week while testing one of our cells in a solar simulator, we noticed...
Hi Experts,
I'm preparing piezo electric generator project, but when I'm searching for piezo disc for my project, i came across different sizes of piezo electric disc, but i didn't found any datasheet,
My question is what's the output voltage/power difference between different diameter...
Homework Statement
A constant current of 3A for 4 hours is required to charge an automotive battery. If the terminal voltage is 10 + 1/2 t V, where t is in hours,
(a) how much charge is transported as a result of the charging?
(b) how much energy is expended?
(c) how much does the charging...
Hi guys I'm not sure if this is the best place to post this but I couldn't find anywhere else.
Would it be possible to program a cell phone charger to detect when a phone is at 20% and then it will start charging? But it won't start charging before 20%. Then it will charge it up to 99% and then...
Hi,
I recently bought a new battery for my phone, and before installing it, checked it's voltage, to be Zero. I understand that there may be protection circuits in the battery, but I assume it should still show a voltage. As it's a Li-on battery the voltage should be between 3.5 and 4.2v. The...
Have been trying to better understand how batteries work. Forgive me if the question's naive.
A half-reaction on one of the electrodes in a battery produces free electrons (for example) and consumes anions (or produces cations). I understand why, if there's an external wire for electrons to...
Homework Statement
When the resistor is R1, in the circle there is the intensity I1 and when the resistor is R2, the intensity becomes I2.Find emf and the inner resistance.[/B]
Homework Equations
I=emf/R+r
The Attempt at a Solution
I1=efm/R1+r
I2=efm/R2+r
efm is equal
I1*(R1+r)=I2(R2+r)...
Homework Statement
A battery is connected with a resistor R1=4 om and then it is replaced with the resistance 9 om. In both cases the heat released in the same time is the same. Find the inner resistor of the battery.
Homework Equations
Q=UIt (U-tension; I-intensity, t-time)
I=e.m.f/R+r
The...
Homework Statement
A 5V battery rated at 1800mAh has a soucre resistance of 10 Ohms. What is the maximum power that can be extracted from the battery?
Homework EquationsThe Attempt at a Solution
I understand that had the battery not had any source resistance then the power out would have been...
I'm going to weld nickel plates/tabs to 18650 cells. Each two batteries will be welded together with a nickel plate. In the center of the nickel plate will be a copper wire to take the 20 amp current flowing from the two cells at 10 amps per cell.
Since I have .2 mm thick nickel plates, to get...
Hello,
according to the lead acid battery standard equations
The overall chemical reaction is:
At the negative terminal the charge and discharge reactions are:
At the positive terminal the charge and discharge reactions are:
My Q?
If we empty all liquid from old battery and add H2O...
On average it takes about 30 seconds for hot water to reach the shower, so for 30 secs water is being wasted. I know running water for 30 seconds doesn't seem that bad but there are a lot of water shortages and droughts going on all around the world. I know its possible to heat water with 9v...
So I have a good car battery at around 12 V and a bad car battery discharged to 6 V. I hook up the batteries (sitting in the cars) with jumper cables. Now, before I turn the ignition switch on the dead battery car, there is effectively a circuit between the the good battery and the bad...
How car alternator charge battery..??
Both equipment are connected with same cable so why battery power does not reached at alternator??
If you guys have any animation it would be helpful..
How battery cut off switch works??
How to apply Battery cut off switch on a vehicle..??
I want to make some electric functions to be operated if the battery is cut off.
For this what should I do..??
Hello,
Sorry for a newbie Q.
If I have a 340ah Lithium LifeP04 12V battery in my camping trailer...
its BMS set to 5% (for a drainage of 95% = 323 usable amp hours)...
it is hooked to an inverter claiming to have 88% efficiency...
how many AC watts (@ 120V) can I expect in theory, or...
No it is not a homework problem I made it myself in order to clearly explain what I am trying to ask.The question could be invalid and silly therefore .If there is a 9V battery What is the potential of it's positive and negative terminals respectively?
If positive terminal's potential is 3V and...
Homework Statement
An electron moves from the positive to the negative terminal of a battery (9V). How much potential energy did it gain or lose?
Homework EquationsThe Attempt at a Solution
Solving for the amount is basic. That's just qV = 14.4 * 10^-19 J
I'm not sure whether it will gain the...
I have a question that how ignition switch works.
Is it is directly connected to battery..? or Alternator..??
Further If I apply a Battery Cut-Off Switch, will ignition works when Battery Cut-Off Switch is off..??
Hello,
Inside an ideal battery, the chemical reaction is reversible (at equilibrium), thus the oxydation-reduction reaction Zn + Cu2+ = Zn2+ + Cu is happening in both ways at the same rate right?
Now, for a real battery, there's resistivity inside it due to many factors, thus the chemical...
Homework Statement
Homework Equations
Ohms Law
R-total = R1 X R2/(R1+R2)
Potential difference (V) = current (I) x resistance (R).
The Attempt at a Solution
[/B]
a) Can complete on my own.
b) Really no clue tbh, I would assume it revolves around ohms law but I'm not sure how it fits in...
Hello forum.
How much current does a 36 volt battery draw under a full load? (Scratch the word battery in this first sentence and replace it with motor). I know I could find it under manufacturers web sites, but I cannot seem to figure it out quickly.
Hello,
I have a question concerning electrochemical cells or batteries. It is said that when the battery is at open circuit, it has small charge separation on its electrodes thus having a potential difference equal to the emf of the battery. When the battery is connected to a circuit, the emf of...
Homework Statement
How do I get the equivilent circuit in this scenario? The battery is not directly connected within the circuit. I know how to find the equivilent resistance in situations where the battery is "inside" the circuit but I am having a little trouble with this one. The voltage...
Hey, I have a project where my group needs to design a drill. I am wondering if anyone here knows how to calculate the torque we get from 3 AA-batteries on 3.6 V (10.6 V together). How does it work? It just needs to assemble furniture, so we don't need very much force on it. Do you know what...
I am doing my wrong project from school. Its basically a science fair but only for the students in the class. I came up with the idea to use piezoelectric plates to charge a capacitor that then charges one of those portable po charge a phone. I know I'm not the first one do this, but I do want...
For instance, at a point 1 meter from a 1 nC charge the voltage (potential difference) from the formula V = Kq/r, is given as 9 volts, 9 J/C.
So what does it then mean to call a battery 9V, 9 J/C? Is this a battery capable of taking a 1 C charge from infinity and pushing to within 1m of a 1 nC...
First off, for my EE100 class I chose to replicate the industrial electrical blankets that are out there.
With that being said, I do own one and can tell that there are some kind of conductive, insulated wires (copper?) that run throughout the blanket which generate the heat. And of course, the...
1. Homework Statement
Homework Equations
P=IV
The Attempt at a Solution
I used the terminal voltage of battery B, that is I minus the voltage across the internal resistance of battery B from the e.m.f. of battery B, then I multiply it with the current which is 2.5A (calculated earlier) ...
People keep asking about setting a car battery on a concrete floor somehow ruining the battery.
Here is the final answer on the subject.
I have the 1930s Popular Science with the original tip in it (but don't ask me which issue). The auto tip was:
"Leaving a car battery on a concrete floor...