Tuesday, August 28, 2012

What About The Future For Reusable Alkaline Battery?

The reusable alkaline was introduced in 1992 as an alternative to disposable batteries.The battery was promoted as a low-cost power source for consumer goods.Attempts were made to open markets for wireless communications,medical and defense.But the big breakthrough never came.Today,the reusable alkaline occupies only a small market and its use is limited to portable entertainment devices and flashlights.The lack of market appeal is regrettable when considering the environmental benefit of having to discard fewer batteries.It is said that the manufacturing cost of the reusable alkaline is only marginally higher than the primary cell or primary battery.

The reusable alkaline battery is inexpensive to buy but the cost per cycle is high when compared to other rechargeable batteries.Whereas nickel-cadmium checks in at $0.04US per cycle based on 1500 cycles,the reusable alkaline costs $0.50 based on 10 full discharge cycles.For many applications,this seemingly high cost is still economical when compared to primary alkaline that provides a one-time use.By only partially discharging the reusable alkaline,an improved cycle life is possible.At 50% depth of discharge,50 cycles can be expected.
The idea of recharging alkaline batteries is not new.Although not endorsed by manufacturers,ordinary alkaline batteries have been recharged in households for many years.Recharging these batteries is only effective,however,if the cells have been discharged to less than 50% of their total capacity.The number of recharges depends solely on the depth of discharge and is limited to a few cycles at best.With each recharge,the amount of capacity the cell can hold is reduced.There is a cautionary advisory.Charging ordinary alkaline batteries may generate hydrogen gas,which can lead to explosion.It is not prudent to charge ordinary alkaline unsupervised.
To compare the operating cost between the standard and reusable alkaline,a study was done on flashlight batteries for hospital use.The reusable alkaline achieved measurable cost savings in the low?intensity care unit in which the flashlights were used only occasionally.The high-intensity care unit,which used the flashlights constantly,did not attain the same result.Deeper discharge and more frequent recharge reduced the service life and offset any cost advantage over the standard alkaline battery.
The reusable alkaline is designed for repeated recharge.Also here,there is a loss of charge acceptance with each recharge.The longevity of the reusable alkaline is a direct function of the depth of discharge;the deeper the discharge,the fewer cycles the battery can endure.Tests performed by Cadex on ‘AA’ reusable alkaline cells showed a high capacity reading on the first discharge.In fact,the energy density was similar to that of nickel-metal-hydride or ni-mh battery.After the battery was fully discharged and recharged using the manufacturer’s charger,the reusable alkaline settled at 60%,a capacity slightly below that of nickel-cadmium.
Repeat cycling in the same manner resulted in a fractional capacity loss with each cycle.The discharge current in the tests was adjusted to 200mA;the end-of-discharge threshold was set to 1V/cell.An additional limitation of the reusable alkaline system is its high internal resistance,resulting in a load current capability of only 400mA.Although adequate for portable radios receivers,CD players,tape players and flashlights,400mA is insufficient to power most mobile phones and video cameras.When considering reusable alkaline,one must realize that the initial energy is slightly lower than that of the standard alkaline.Cost savings are realized if the batteries are never fully discharged but have a change to be recharged often.

Advantages

  • Inexpensive – can be used as a direct replacement for non-rechargeable (primary) cells.
  • More economical than non-rechargeables – allows several recharges.
  • Low self-discharge – can be stored as a standby battery for up to 10 years.
  • Environmentally friendly – no toxic metals used, fewer batteries are discarded.
  • Maintenance free – no need for cycling; no memory.

Limitations

  • Limited current handling – suited for light-duty applications like portable home entertainment, flashlights.
  • Limited cycle life – for best results, recharge before the battery gets too low.


 By | Published: April 28, 2012

Wednesday, August 22, 2012

Advantages Of D Alkaline Batteries

D alkaline battery also called as the D cell is the largest type of commonly available electrochemical cell. The average output voltage of a non-rechargeable D-cell is 1. 5 volts while the normal rechargeable D cells have a lower output voltage of 1. 2 V. However, some cells made with special method can operate at even higher voltages of 1. 6 V.
Every D cell comprises of a cylindrical metal body with electrical contacts at each critical. On account of their large size and greater power capacity, these cells find their utility in high-drain applications. The D cells are ideally used in large flashlights, portable CD/Cassette players, radio receivers and transmitters.
The working of these batteries is based on either of the two technologies: the alkaline battery or the Zinc H2o and technology. However, the Alkaline version has emerged as the more preferred choice for usage in applications with a greater power demand. Following are the advantages offered by the Alkaline batteries over Zinc Carbon battery:
 -- Fairly longer ledge life (in some cases exceeding beyond 6 years)
-- High performance delivered even at a temperature just -30C
-- They are an economical choice to the Zinc Carbon battery The D batteries can be classified into two main types: the normal rechargeable and the non-rechargeable type.
The not for normal rechargeable batteries are known as primary cells and the normal rechargeable types are called as the supplementary cells. If you are a heavy user of D batteries then the normal rechargeable NiMH type battery may be the real option for you. The rechargeable battery, in some cases, has a considerably less capacity than the pre-charged D battery but last up to 1000 charge series.




by Dishy Battery

Monday, August 20, 2012


Tuesday, July 24, 2012

How do rechargeable (that is, zinc-alkaline or nickel-cadmium) batteries work and what makes the reactions reversible in some batteries, but not in others?

Michael M. Lerner, an associate professor of chemistry at Oregon State University, responds:
"One of the necessary conditions for a battery to be rechargeable is that the underlying chemical changes that occur during an electrical discharge from the cell must be efficiently reversed when an opposite electrical potential is applied across the cell. In nickel-cadmium (NiCad) batteries, for example, the Cd(OH)2 and Ni(OH)2 that are formed during cell discharge are readily converted back to the original electrode materials (Cd and NiOOH), when the cell is recharged.
"In contrast, nonrechargeable, or primary, batteries can be based on irreversible chemical changes. For example, the carbon-fluoride- lithium primary batteries often used in cameras generate energy by converting (CF) n and Li metal to carbon and LiF. But the starting material at the battery' s cathode, (CF)n, is not reformed when a reverse potential is applied. Instead the cell electrolyte decomposes, and eventually the fluoride is oxidized to form fluorine gas.
"A reversible chemical change is not the only requirement for rechargeable batteries, however. To be classified as rechargeable, the battery must be able to undergo the reverse reaction efficiently, so that hundreds or even thousands of recharging cycles are possible. In addition, there must often be provisions to ensure that the recharging process can occur safely.
"The alkaline batteries (which are generally based on the conversion of MnO2 and Zn to Mn3O4 and ZnO) offer an excellent example of this last point. Although the chemical changes at the electrodes can be reversed, until recently alkaline batteries were manufactured only to function as primary cells. Recharging one of these primary cells could allow the battery to be reused, but the possible number of recharging cycles for such a cell is very limited--it performs more poorly with each recharge. More important, recharging an old-fashioned alkaline battery is not safe. During or after a recharge, the battery might generate enough hydrogen gas to cause an explosion. In their rechargeable form, alkaline cells have undergone several changes. They have been redesigned to allow for a more efficient reverse reaction, they contain a catalyst to minimize hydrogen formation and they have safety vents that prevent the buildup of excess pressure during recharging."
Frank McLarnon is a staff scientist and principal investigator in the Energy & Environment Division of Lawrence Berkeley National Laboratory. He clarifies why some reactions are irreversible:
"All batteries, both rechargeable and nonrechargeable, undergo electrochemical reactions. When a battery is discharged, an electrochemical oxidation reaction proceeds at the negative electrode, and an electrochemical reduction reaction occurs at the positive electrode. When one attempts to recharge a battery by reversing the direction of electric current flow, the opposite takes place: a reduction reaction proceeds at the negative electrode, and an oxidation reaction takes place at the positive electrode.
"In the case of the rechargeable battery, the electrochemical oxidation- reduction reactions are reversible at both electrodes. For example, when the battery is recharged, the overall electrochemical reduction reaction at the negative electrode is identical to the electrochemical oxidation reaction that proceeded at the negative electrode when the battery was discharged, only written in reverse.
"In the case of the nonrechargeable battery, when one attempts to recharge the battery by reversing the direction of electron current flow, at least one of the electrochemical oxidation-reduction reactions is not reversible. When the battery is charged, the overall reduction reaction that proceeds at the negative electrode may not be the true reverse of the oxidation reaction that proceeded when the battery was discharged. For example, metal oxidation might be the sole oxidation reaction during battery discharge, whereas the formation of hydrogen (a highly inflammable and therefore dangerous gas) might be a significant reduction reaction during battery recharging.

"An added requirement for a well-behaved (that is, long-lived) rechargeable battery is that not only must the electrochemical oxidation- reduction reactions be reversible, they must also return the electrode materials to their original physical state. For example, rough or filamentary structures may form in the battery after repeated charge- discharge cycles. These structures can result in unwanted growth of the electrode and subsequent electronic contact between the battery electrodes- -a short circuit.
"Because of these requirements, the development of a well-behaved rechargeable battery is significantly more difficult than the development of a nonrechargeable battery. In the case of the nickel-cadmium battery, the cadmium electrode has two important features. First, the rate of hydrogen formation on cadmium is very slow (compared with that on pure zinc or pure iron, for example). Second, the solubility of cadmium in basic aqueous electrolyte solutions is sufficiently low that the cadmium does not tend to dissolve in the electrolyte and migrate to the positive electrode or elsewhere within the battery. At the same time, however, the cadmium is sufficiently soluble that its reduction can proceed easily, and it can form compact cadmium structures during battery recharge; the solubilities of most other metals are either too high or too low. These and other fundamental factors have allowed the successful development of the rechargeable nickel-cadmium battery

Scientific American
October 21,1999

 

What is an Alkaline Battery

What is an Alkaline Battery

The world’s energy needs are ever greater and more varied as time goes on. One source of energy has developed as a convenient way to power electronic devices, and that is the alkaline battery. Batteries are essentially small containers that hold chemicals which react to produce electricity. The alkaline battery is the most common and versatile type of battery used, and it gets its name because of the alkaline electrolyte potassium chloride, which is one of the chemicals it contains.
Each alkaline battery has two ends, or terminals -- a positive and a negative terminal. Inside the battery, a chemical reaction produces electrons, which gather at the negative terminal of the battery. However, unless the negative terminal is connected to the positive terminal, the chemical reaction stops and no more electricity is produced. This is the reason that an alkaline battery can sit in a drawer or on a shelf for a long time and still have plenty of power when it is needed. If it is not used, the battery does not wear out in a short period of time.Usually, the battery is used by connecting some sort of device to it, such as a motor, the light bulb in a flashlight, or a radio, for example. The electrons flow out of the negative terminal of the battery, through a wire to the device. There they power the device before flowing back to the positive terminal. This completes a circuit, allowing the chemical reaction to continue, and the battery to produce more electrons. When the device is switched off, the circuit is broken so that electrons can no longer flow in a complete circle. The battery then stops producing electrons, since the terminals are no longer connected.
The alkaline battery is one of the more modern types of battery used, having been introduced first in the 1960s. The very first battery was created by scientist Alessandro Volta in 1800. Volta made his battery by stacking alternating layers of zinc, salt water-soaked blotting paper, and silver. The higher the stack, the higher the voltage produced by this arrangement. This type of battery was known as the voltaic pile. The modern alkaline battery still uses the same fundamental principles as the voltaic pile, namely two different types of metal, separated by a liquid which conducts electricity, with a negative and a positive terminal.
One of the latest advancements has been the development of the rechargeable alkaline battery. A different formula and blend of materials allows these to not only be recharged, unlike the traditional alkaline battery, but to hold their charge for years, unlike other types of rechargeable batteries. These batteries represent a form of energy storage that is ultimately less costly to the consumer, and one that has less environmental impact as well.

Article by WiseGeek

Wednesday, April 25, 2012

Shelf Life of Alkaline Batteries

Shelf Life of Alkaline Batteries

What Is the Shelf Life of an Alkaline Battery?


Consumers use alkaline batteries for several products in their home, such as electronic toys, radios, clocks, smoke detectors and television remote controls. If you keep a stock of batteries available, it may help to know their shelf life.

Function

  • The purpose of an alkaline battery is to power electronic devices until the charge within the battery runs out.

Composition

  • Alkaline batteries, also known as dry cell batteries, have a steel outer casing. Fabric inside the core separates the electrodes from the anodes. The electrolyte is a potassium hydroxide solution in water that carries the ions within the battery cell.

Process

  • Alkaline batteries produce power through a chemical reaction that begins to occur when you put the battery in a device, complete the circuit and combine the electrodes and anodes. The battery produces electrical energy because the battery contains the chemical reaction.

Shelf Life

  • While an alkaline battery is reliable, it has a shelf life of about 7 to 10 years. Around that time, the chemicals within the battery become stagnant and no longer produce a chemical reaction to power the battery.

Considerations

  • Some people believe that placing unused batteries in a freezer extends their shelf life. While the chemical reaction within an alkaline battery does slow at lower temperatures when in a device, there is no documentation available to support the assumption that a disconnected battery has a longer shelf life when kept cold.
  • Alkalines major advantages (compared to the zinc-carbon battery system) are a high energy density; the ability to operate continuously at relatively high discharge rates over a wide temperature range (due to its lower internal resistance); and a shelf life in excess of four years. The cost of the alkaline battery, on a service life basis, is lowest in medium to high drain applications.

    CHEMISTRY
    The components of the alkaline-manganese battery are a zinc anode, a manganese dioxide cathode, and a highly conductive potassium hydroxide electrolyte.

    PERFORMANCE CHARACTERISTICS
    Voltage
    The open circuit voltage ranges from 1.5 to 1 .6V, depending on cathode formulation. Typical median operating voltage ranges from 1.3 to 1.1V under moderate discharge conditions.

    Discharge Characteristics
    Moderately sloping discharge curve.

    Energy Density
    75 Wh/lb. (163 Wh/kg); 6.5 Wh/in.3 (398 Wh/l).

    Effect of Discharge Load and Temperature
    Capable of performance at high discharge rates; typical temperature range: -4°F to 130°F (-20°C to 54°C).

    Shelf Life
    Up to 85% capacity remaining after 4 years of storage at 70°F (21°C).
By Michelle L Crame, eHow Contributor
January 21, 2010

Monday, August 22, 2011

MN1300 Alkaline Batteries

MN1300 Alkaline Batteries






Alkaline Batteries are all over the place: in our cars, our PCs, laptops, portable MP3 players and cell phones. A battery is essentially a can full of chemicals that produce electrons. Chemical reactions that produce electrons are called electrochemical reactions.

If you look at any battery, you'll notice that it has two terminals. Electrons collect on the negative terminal of the battery. If you connect a wire between the negative and positive terminals, the electrons will flow from the negative to the positive terminal as fast as they can. Normally, you connect some type of load to the battery using the wire. Inside the battery itself, a chemical reaction produces the electrons. The speed of electron production by this chemical reaction (the battery's internal resistance) controls how many electrons can flow between the terminals. Normal batteries have generally 1.5V per cell voltage (except some Lithium cells which have 3V voltage). The batteries which have higher voltage output are built generally from many 1.5V cells in series all put inside same "case". Since there are no real industry standards, many terms used by battery manufacturers have become misleading marketing hype.

Although the terms battery and cell are often used interchangeably cells are the building blocks of which batteries are constructed. Batteries consist of one or more cells that are electrically connected.The world of batteries divides into two major classes: primary and secondary batteries. Primary batteries such as the common flashlight battery are used once and replaced. The chemical reactions that supply current in them are irreversible. Secondary batteries (for example, car batteries) can be recharged and reused. They use reversible chemical reactions. By reversing the flow of electricity i.e. putting current in rather than taking it out, the chemical reactions are reversed to restore active material that had been depleted. Secondary batteries are also known as rechargeable batteries, storage batteries or accumulators.

As a battery is used, the amperage is consumed and the voltage drops. There is a formula for a ballpark estimate for battery life:
Estimated total battery life = (Ib / Id) x 0.7
Where: Ib = Total Capacity Rating of battery (mAh) and Id = Current Consumption of the device in milliamps (mA)
Use of this formula does not guarantee that you will get the determined battery life. Other factors such as weather condition (temperature, humidity, etc.), and battery condition can extend/shorten the battery life. This formula cannot be used to calculate battery life for alkalines. Battery state can be somewhat determined with the battery voltage. Please note that batteries do not show their correct voltage unless under a load. Battery testers are designed to provide this load; however, when testing batteries with a multimeter, you must have the meter set to measure DC voltage and place the battery under load by using a resistor in parallel with the test leads of the meter. How the battery voltage drops during the use varies from battery type to another.


Alkaline batteries are single-use batteries, but provide a higher start voltage and longer life than many other single use batteries. The capacity rating for alkaline batteries is not a fixed number on alkaline batteries, although it can be safely assumed that an alkaline battery will last significantly longer (2-3 times as long) as a same-size rechargeable under the same conditions. Alkalines do not have a fixed capacity rating because where the discharge rate of rechargeable batteries is a straight line, the discharge rate for alkalines slopes depending on the current drain. The higher the current drain, the faster the battery discharges. In alkaline batteries, the sloping discharge curve makes it impossible to accurately provide a mAh rating; the rating would vary depending on discharge rate and temperature. Alkaline batteries are significantly heavier than many other battery types for the same size, but they can store lots of energy (few times more than "regular" batteries). Alkaline batteries can take storage nicely when not used. Alkaline batteries stored at "room temperature" self discharge at a rate of less than two percent per year. However, if alkaline batteries are stored at higher temperatures they will start to lose capacity much quicker. At 85 degrees F they only lose about 5% per year, but at 100 degrees they lose 25% per year.

There is a variation of alkaline cell that can be charged with a limited number of times: Rayovac sells rechargable akaline batteries. Rechargeable alkalines are really just normal alkalines with a beefy casing to reduce leakage, but the full charge drops off significantly even after the first recharge cycle and gets worse from there.

epanaorama.

Tuesday, August 2, 2011

MN1500 Alkaline batteries




Duracell MN1500 CopperTop is new and improved to meet the growing needs of consumers. The technology of CopperTop has been upgraded to provide advanced performance in popular battery powered devices. CopperTop is best suited when you need reliable, long lasting life from your everyday devices.


Alkaline cells have an impressive energy capacity, usually
greater then 2500mAh. But this is only one of several factors that affects
the performance of a cell. At certain points in their operation Digicams
have extremely high power demands. The power a cell or battery can deliver
depends on both the voltage it can provide, and the electrical current it
can deliver (the power supplied is actually the voltage multiplied by the
current). The voltage is limited, it is fixed by the chemistry of the cell,
so the only way to deliver that power is with a large current. The
essential problem with alkaline batteries is that they have great difficulty
providing these large electric currents.

Alkaline cells are brilliant, however, in the right application. For low
power devices, or devices that are used infrequently e.g. doorbells, radios,
remote controls etc., they are superb. They have a huge energy capacity,
and a shelf-life of several years. . (Many
pro-photographers keep some high quality alkalines in their bag so that they
can always take a few shots if their rechargeables run out etc.)