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.
Hi i embarked on a project to design a battery charging system using an alternator, an electric motor and a battery all connected in a closed loop.
The battery powers the electric motor and in turn the electric motor powers the alternator and finally the alternator charges the battery.
My...
Homework Statement
Three capacitors C1–C3, all initially uncharged, are placed in the circuit shown. The capacitances are C1=8.9 μF, C2=20 μF, C3=12.2 μF, and the battery voltages are V1=18 V, V2=10 V, V3=18 V.
What is the magnitude q1 of the charge on capacitor C1 once equilibrium has been...
Hello. As a memorial I am trying to build a light-sensitive unit that will make an LED continuously glow at night. I want to put this in an extremely remote place and be reasonable confident that it will continue to operate indefinitely. The idea is that once it becomes dark, a photodiode will...
Question
The α-emitter 210, 84 Po is used in a nuclear battery. The kinetic energy of the emitted alpha particles can be worked out from energy and momentum conservation. It is converted into electrical energy at 5.0% efficiency.
(a) Determine the initial power output (in W) of the battery...
I am lost in the middle of a vast desert in my swim shorts. There is nothing anywhere around me as far as you can see. In front of me is a 12volt battery (say lead acid) with no markings or other indicators of polarity. there are 2 wires long enough to make a connection to the emergency...
I've been researching Lithium Iron Disulfide Batteries, but I've been unable to find the half-equations for the Cathode and Anode.
Cathode - Iron Disulfide
Anode - Lithium
Electrolyte - Organic Solvent Blend (Propylene Carbonite, Dioxolane, Dimethoxyethane)
The overall equation is...
Homework Statement
An AA battery (1.5 V potential) is connected to a parallel-plate capacitor having 6.00cm-diameter plates spaced 4mm apart. How much charge does the battery move from one plate to the other?
Homework Equations
V=Q/C
C=A\kappa\epsilon/dThe Attempt at a Solution
Plugged in...
1. What is the potential difference DeltaVab between points a and b when the switch is open? Closed?
2. DeltaV = IR
3. I solved I for the battery, which is 8A. What do I use for my R value to solve for DeltaV between a and b, though? I tried, for example, DeltaV = IR = 8A*6ohms = 48V. I guess...
Problem 5: Current, Energy and Power A battery of emf ε has internal resistance i R ,
and let us suppose that it can provide the emf to a total charge Q before it expires.
Suppose that it is connected by wires with negligible resistance to an external (load) with
resistance L R .
a) What is...
I'm asking this question on behalf of another person who doesn't know english well.
What he wants to know is the relationship between energy extracted from a battery and the corresponding reduction in mass of the battery, and if it would be possible to measure the difference with some type of...
Discharging a capacitor at a "battery like" rate
We all know that capacitors discharge at a rate determine by the time constant of the circuit they are hooked up to (tau = RC). This discharge takes the form of a "dieing exponential" with respect to stored energy and likewise voltage. Capacitors...
Homework Statement
A rechargeable AA battery with a mass of 25.0g can supply a power of 1.20W for 50.0mins.
What is the difference in mass between a charged and an uncharged battery?
Homework Equations
W = Pt
W = K = gmc^2 - mc^2
where g = 1/(1-(v/c)^2)^(-1/2)
E (total) = gmc^2 = K...
the circuit is as shown.
http://img186.imageshack.us/img186/6627/circuitg.jpg
now i have to find the current from the battery. now the book says since the capacitor is charged its branch will no more have any current and we can neglect that branch. now my qs is. after the capacitor is...
Homework Statement
does a flashlight battery have an internal resistance? explain.
this problem is for my lab, and we are farther ahead in lab than in lecture. so i haven't actually learned this material yet.
Homework Equations
i'm not really sure.
R=∆V/I
also,
-VB + VR + VM +...
Homework Statement
To recharge a 5V battery, a battery charger must move 7x10^6 C of charge from the neg. to pos. terminal. How much work is done by the charger in joules?
Homework Equations
QV=U
The Attempt at a Solution
If the battery needs to be recharged, isn't the potential...
Homework Statement
One rechargeable battery of mass 15.0 g delivers to a CD player an average current of 15.5 mA at 1.00 V for 2.50 hr before the battery needs to be recharged. The recharger maintains a potential difference of 2.00 V across the battery and delivers a charging current of 10.0...
I'm wiring together 25 rgb leds, each take 3V and I was wondering what would be the most efficient way to wire up as many as possible off one power source using resistors. Which resistors should I use? Series or Parallel? 9V or 12V battery?
This is for a small project I'm working on myself...
Homework Statement
A 12-V battery is connected to three capacitors in series. The capacitors have the following capacitances: 4.0uF, 14uF, and 33uF.
Homework Equations
R = V/I
The Attempt at a Solution
I'm thinking you add the capacitances since they are in series (do i need to...
Sorry if this is the wrong forum. When I just touch any part of the metal of both terminals on a 9V battery with a multimeters probes the meter displays the voltage (although it said 20V not 9V for some reason). What I'm wondering is why people don't get electric shocks from touching both...
Hye guys,
I'm just a beginner in the area..i have a project of hand-cranked battery charger..
I supposed to improve the current charger in every way possible..
How could i the miniature generator, to generate the energy by turning the crank..
Is there any diagram that i can study or any...
I've got a 12V1.3AH/20HR battery and I tried charging it with my 12V solar pannels of 200mAh max output together (2 solar panels with 100mAh max designed for charging car battery trough cigarette lighter thing) but the solar panels their lights wouldn't go off meaning no power were given to the...
I'm attempting to figure out why my car isn't starting. I've reseated all the grounds and made sure the ground connections were clean and bare. I've cleaned the battery terminals and clamps with a wire brush as there was some corrosion on the terminals.
I charged the battery two days ago due...
I'm having issues with overheating and need a little help.
I have 8 6v4ah rechargeable lead-acid batteries. I wire 2 in series for 12 volts. Then i wire the sets of 2 in parallel, because I want to keep my system at 12 volts. That means I have 16 amps. Every time I add more sets of...
I've noticed that some devices (when they're low on battery charge) can be shut off and will regain some charge while they're off (if you leave them off long enough).
What's going on here, physically?
Hi there,
I have been doing research on a lil private project of my own, and am looking for some help.
Would it make sense to use nichrome wire to build a heating element that will heat to 80-100 degrees? It seems that nichrome is great for heating way way past that temperature. I want to...
The Lead Acid Battery in my H-D '09 FXDF is rated 12V at 19Ah. If I understand the math correctly, I would need a 12V capacitor rated to 5,700F. Is this accurate?
1 F = 1 As/V
1 Ah = 3600 As
19Ah x (3600As/1Ah) = 68,400As
(68,400As/12V) x (1F/[1As/V]) = 5,700 F
As I understand it...
Any help is appreciated,
I have a 11.1v battery system, an I would like to install a low battery indicator. I would like the indicator to be a single red LED that initiates when the voltage drops below 7v. Size is definitely a concern here.
I have looked online at various templates, but I...
Homework Statement
Two almost identical lead-acid accumulator batteries, X and Y, are connected with opposing polarities in a circuit which includes an ammeter, an ideal millivoltmeter and a resistor R as shown in figure below.
When S1 is closed with S2 left open, the millivoltmeter reads 50...
Dear Experts,
I am fascinated how a cell phone battery charger knows when the battery is fully charged such that it cuts off the power to prevent further charging.
If its based on sensing a particular voltage has been reached, i wonder how is that achieved?
Or is it achieved by measuring...
we have to build vehicle that can transport a d cell battery 7 meters as fast as possible using the potential energy of no more than 2 kilograms falling from 80cm.
we want to use this design:
http://www.scioly.org/w/images/6/69/SC-brake3diag.gif...
Homework Statement
A 3.50 µF capacitor is charged by a 13.0 V battery. It is disconnected from the battery and then connected to an uncharged 4.44 µF capacitor (Fig. 17-29).
Figure 17-29
Determine the total stored energy at the following points in time.
(a) before the two...
Questions about Battery "Memory"
I've heard that rechargeable NiCad batteries can be damaged so that they experience a large drop in voltage (and thus appear to be dead) before they are completely dead by being discharged to a point (like halfway) and then being recharged. Then I've heard that...
I have a first generation Apple iTouch 16 GB, and frequently download podcasts to watch and listen to. With over 1 million applications written, I have searched in vain to locate an application that will allow you to launch a video, and instead of displaying video and audio to suppress the...
Hi all,
I'm trying to nail very precisely the effects of a battery in terms of charge separation. In particular: when and what points are excess charges seen in a typical circuit powered by a battery.
A. Prior to wires being attached to the battery, you just have the battery itself. My...
Alright, so here goes, and by the way, this isn't homework, just in case you're wondering.
Question 1: So, i have a 12vdc 500amp battery/car inverter and a 12vdc 11amp sump pump. If I wire it up, approximately how long will they last?
Question 2: Also, I have a power inverter for my car, can I...
Could somebody give me detailed explanation how Li-ion chemistry works?
For example,if Li ions (cathions) just migrate from one host material (such as graphite) to
another (such as Cobalt oxide) where are electrons taken from to run in external circuit?
In more common type of battery such as...
I am working on putting a new battery rack into a substation. I was re-reading the NESC and came across section 143. This section suggests it is not recommended to anchor my rack to both the floor and the wall. Can anyone explain why this is not recommended?
Here is a diagram of the circuit I am analyzing:
http://www.sixtheorem.com/images/1.png
I observe that bulb 2 does not light when the switch is closed. Could someone please explain what is happening here?
And, what happens if I reverse the direction of battery B?
Hi everybody,
I would like to use a 9V pp3 battery with a device with a rate of order of µA. Iwanted to use Peukert's law to calculate the duration of my battery but I am not quite sure if it is applicable for such low current... Won't a battery with 1200mAh capacity discharge too fast...
Hello Experts! :!)
I have a LED light with 3 leds, a switch and a resistor i added to adjust for higher supply voltage.
I removed the batteries and connect it to a DC voltage source from power adaptor.
Without anything connected as load to this DC source, the voltage read 5.17V...
How are the cells (say 2V) of a typical lead acid battery connected in series to increase voltage to 12V when all the neg. plates are connected together and all the positive plates are connected together which as I understand is the principle of connecting two batteries in parallel (pos...
Homework Statement
In discharge mode, calculate the variation in mass of the compounds of a lead-acid battery if the sufuric acid mass decreases by 294g (3 moles).
Homework Equations
The semirreactions:
Pb \to P{b^{2 + }} + 2{e^ - }
4{H^ + } + Pb{O_2} + 2{e^ - } \to P{b^{2 + }} +...
Homework Statement
Homework Equations
KE = 1/2mv^2
F_B=I(L x B)
The Attempt at a Solution
I have the answer to this, (D) but I don't know how to get it.
I know that the gained kinetic energy is equal to the lost potential energy of the system. What's the potential energy of...
Hi,
Newby here trying to design a small piece of lawn equipment in my shop. I want to design my own leaf blower using a small electric motor to turn the shaft of a squirrel cage blower. A friend of mine built himself this same system except he used an old lawnmower motor. It works great but...
Homework Statement
An automotive battery has an emf of 11.1 V. When supplying power to the starter motor, the current in the battery is 20.0 A, and the terminal voltage of the battery is 10.6 V.
a.)How much power is delivered by the battery due to the chemical reactions within the battery...
Hi all,
I'm using NS2 to simulate wireless sensor networks. I want an estimate of the initial sensor battery energy. I know that each sensor node uses 2 AA batteries. I have no assumptions about the current. I search for a while on the internet but couldn't find a direct estimate.
Thanks...
This is a piece of circuit:
.
I2 = 2A, I1 = 4A, R = 10\Omega, VB - VC = 12V. Find Iy (that goes over Ry), Rx, Ry and VA - VD
The Attempt at a Solution
I can find Rx pretty easily, using that VB - VC = 12V, then, since V= IR, VB - 10 V - I2*Rx - VC = 0.
I also find, using...
Homework Statement
A cordless drill battery charger is rated at 30.0 W but requires only 13.5 V. It contains a transformer that converts 120 V household voltage.
(b) What is the current in the secondary coil while the battery is charging?
(c) What is the current in the primary coil...
Does the emf of a battery remain its specified value for a long time. It is under discharging when connected to the external resistor, so shouldn't its emf value continuously decrease in that case?
A battery's emf value increases from 0(completely discharged state) to the specified value...