Voltage-based state-of-charge is popular for wheelchairs

June 17 [Mon], 2013, 12:35
Measuring state-of-charge by voltage is the simplest method, but it can be inaccurate. Cell types have dissimilar chemical compositions that deliver varied voltage profiles. Temperature also plays a role. Higher temperature Aspire 1830T replacement raises the open-circuit voltage, a lower temperature lowers it, and this phenomenon applies to all chemistries in varying degrees.

The most blatant error of voltage-based SoC occurs when disturbing the battery with a charge or discharge. This agitation distorts the voltage and no longer represents the true state-of-charge. To get accurate measurements, the battery needs to rest for at least four hours to attain equilibrium; battery manufacturers recommend 24 hours. Adding the element of time to neutralize voltage polarization does not sit well with batteries in active duty. One can see that this method is ill suited for fuel gauging.

Each battery chemistry delivers a unique discharge signature that requires a tailored model. While voltage-based SoC works reasonably well for a lead acid battery that has rested, the flat discharge curve of nickel- and lithium-based batteries renders the voltage method impracticable. And yet, voltage is commonly used on consumer products. A “rested” Li-cobalt of 3.80V/cell in open circuit indicates a SoC of roughly 50 percent.
The discharge voltage curves of Li-manganese, Li-phosphate and NMC are very flat, and 80 percent of the stored energy remains in this flat voltage profile. This characteristic assists applications requiring a steady voltage but presents a challenge in fuel gauging. The voltage method only indicates full charge and low charge and cannot estimate the large middle section accurately.

Lead acid has diverse plate compositions that must be considered when measuring SoC by voltage. Calcium, an additive that makes the battery maintenance-free, raises the voltage by 5–8 percent. Temperature also affects the open-circuit voltage; heat raises it while cold causes it to decrease. Surface charge further fools SoC estimations by showing an elevated voltage immediately after charge; a brief discharge before measurement counteracts the error. Finally, AGM batteries produce a Aspire 1551 replacementslightly higher voltage than the flooded equivalent.

When measuring SoC by open circuit voltage, the battery voltage must be truly “floating” with no load present. Installed in a car, the parasitic load present makes this a closed circuit voltage (CCV) condition that will falsify the readings. Adjustments must be made when measuring SoC in the CCV state by including the load current in the calculation. In spite of the notorious inaccuracies, most SoC measurements rely on the voltage method because it’s simple. Voltage-based state-of-charge is popular for wheelchairs, scooters and golf cars.

A fuse cuts the current flow if the skin temperature of the cell approaches

April 27 [Sat], 2013, 15:16
There are two basic types of lithium-ion chemistries: cobalt and manganese (spinel). To achieve maximum runtime, cell phones, digital cameras and laptops use cobalt-based lithium-ion. Manganese is the newer of the two chemistries and offers superior thermal stability. It can sustain temperatures of up to 250°C (482°F) before becoming unstable. In addition, manganese has a very low internal resistance and Latitude E6400 laptop battery can deliver high current on demand. Increasingly, these batteries are used for power tools and medical devices. Hybrid and electric vehicles will be next.

The drawback of spinel is lower energy density. Typically, a cell made of a pure manganese cathode provides only about half the capacity of cobalt. Cell phone and laptop users would not be happy if their batteries quit halfway through the expected runtime. To find a workable compromise between high energy density, operational safety and good current delivery, manufacturers of lithium-ion batteries can mix the metals. Typical cathode materials are cobalt, nickel, manganese and iron phosphate.

Let me assure the reader that lithium-ion batteries are safe and heat related failures are rare. The battery manufacturers achieve this high reliability by adding three layers of protection. They are: [1] limiting the amount of active material to achieve a workable equilibrium of energy density and safety; [2] inclusion of various safety mechanisms within the cell; and [3] the addition of an electronic protection circuit in the battery pack.

These protection devices work in the following ways: The PTC device built into the cell acts as a protection to inhibit high current surges; the circuit interrupt device (CID) opens the electrical path if an excessively high charge voltage raises the internal cell pressure to 10 Bar (150 psi); and the safety vent allows a controlled release of gas in the event of a rapid increase in cell pressure. In addition to the mechanical safeguards, the electronic protection circuit external to the cells opens a solid-state switch if the charge voltage of any cell reaches 4.30V. A fuse cuts the current flow if the skin temperature of the cell approaches 90°C (194°F). To prevent the battery from over-discharging, the control circuit cuts off the current path at about 2.50V/cell. In some Studio 1555 laptop battery applications, the higher inherent safety of the spinel system permits the exclusion of the electric circuit. In such a case, the battery relies wholly on the protection devices that are built into the cell.

We need to keep in mind that these safety precautions are only effective if the mode of operation comes from the outside, such as with an electrical short or a faulty charger. Under normal circumstances, a lithium-ion battery will simply power down when a short circuit occurs. If, however, a defect is inherent to the electrochemical cell, such as in contamination caused by microscopic metal particles, this anomaly will go undetected. Nor can the safety circuit stop the disintegration once the cell is in thermal runaway mode. Nothing can stop it once triggered.

Ignoring the performance criteria of a battery

March 18 [Mon], 2013, 15:46
Most new batteries go through a formatting process during which the capacity gradually increases and reaches optimal performance at 100–200 cycles. After this mid-life point, the capacity gradually begins decreasing replacement Pavilion G42 batteryand the depth of discharge, operating temperatures and charging method govern the speed of capacity loss. The deeper the batteries are discharged and the warmer the ambient temperature is, the shorter the service life. The effect of temperature on the battery can be compared with a jug of milk, which stays fresh longer when refrigerated.

Most portable batteries deliver between 300 and 500 full discharge/charge cycles. Fleet batteries in portable devices normally work well during the first year; however, the confidence in the portable equipment begins to fade after the second and third year, when some batteries begin to lose capacity. New packs are added and in time the battery fleet becomes a jumble of good and failing batteries. That’s when the headaches begin. Unless date stamps or other quality controls are in place, the user has no way of knowing the history of the battery, much less the performance.

The green light on the charger does not reveal the performance of a battery. The charger simply fills the available space to store energy, and “ready” indicates that the battery is full. With age, the available space gradually decreases and the charge time becomes shorter. This can be compared to filling a jug with water. An empty jug takes longer because it can accept more water than one with rocks. Figure 1 shows the “ready” light that often lies.

Many battery users are unaware that weak batteries charge faster than good ones. Low performers gravitate to the top and become available by going to “ready” first. They form a disguised trap when unsuspecting users require a fully charged battery in a hurry. This plays havoc in emergency situations when freshly charged batteries are needed. The operators naturally grab batteries that show ready, presuming they carry the full capacity. Poor battery management is the common cause of system failure, especially during emergencies.

Failures are not foreign in our lives and to reduce breakdowns, regulatory authorities have introduced strict maintenance and calibration guidelines for important machinery and instruments. Although the battery can be an integral part of such equipment, it often escapes scrutiny. Thereplacement Pavilion dm3 batteryas power source is seen as a black box, and for some inspectors correct size, weight and color satisfies the requirements. For the users, however, state-of-function stands above regulatory discipline and arguments arise over what’s more important, performance or satisfying a dogmatic mandate.

Ignoring the performance criteria of a battery nullifies the very reason why quality control is put in place. In defense of the quality auditor, batteries are difficult to check, and to this day there are only a few reliable devices that can check batteries with certainty. Read about Difficulties with Battery Testing.

The battery is an elusive scapegoat

March 18 [Mon], 2013, 15:45
A battery is a corrosive device that begins to fade the moment it comes off the assembly line. The stubborn behavior of batteries has left many users in awkward situations. The British Army could have lost the Falklands War in 1982 on account of uncooperative batteries. The officers assumed that a replacement 537627-001 would always follow the rigid dictate of the military. Not so. When a key order was given to launch the British missiles, nothing happened. No missiles flew that day. Such battery-induced letdowns are common; some are simply a nuisance and others have serious consequences.

Even with the best of care, a battery only lives for a defined number of years. There is no distinct life span, and the health of a battery rests on its genetic makeup, environmental conditions and user patterns.

Lead acid reaches the end of life when the active material has been consumed on the positive grids; nickel-based batteries lose performance as a result of corrosion; and lithium-ion fades when the transfer of ions slows down for degenerative reasons. Only the supercapacitor achieves a virtually unlimited number of cycles, if this device can be called a battery, but it also has a defined life span.

Battery manufacturers are aware of performance loss over time, but there is a disconnect when educating buyers about the fading effect. Runtimes are always estimated with a perfect battery delivering 100 percent capacity, a condition that only applies when the battery is new.While a dropped phone call on a consumer product because of a weak battery may only inconvenience the cellular user, an unexpected power loss on a medical, military or emergency device can be more devastating.

Consumers have learned to take the advertised battery runtimes in stride. The information means little and there is no enforcement. Perhaps no other specification is as loosely given as that of battery performance. The manufacturers know this and get away with minimal accountability. Very seldom does a user challenge the battery manufacturer for failing to deliver the specified battery performance, even when human lives are at stake. Less critical failures have been debated in court and replacement 586029-001punished in a harsh way.

The battery is an elusive scapegoat; it’s as if it holds special immunity. Should the battery quit during a critical mission, then this is a situation that was beyond control and could not be prevented. It was an act of God and the fingers point in other directions to assign the blame. Even auditors of quality-control systems shy away from the battery and consider only the physical appearance; state-of-function appears less important to them.

Lithium-ion does not have memory problems like nickel-cadmium batteries

January 14 [Mon], 2013, 15:37
Batteries live longer if treated in a gentle manner. High charge voltages, excessive charge rate and extreme load conditions have a negative effect on battery life. The longevity is often a direct result of the environmental stresses battery for Vostro 1710 battery applied. The following guidelines suggest ways to prolong battery life.

-The time at which the battery stays at 4.20/cell should be as short as possible. Prolonged high voltage promotes corrosion, especially at elevated temperatures. Spinel is less sensitive to high voltage.

-3.92V/cell is the best upper voltage threshold for cobalt-based lithium-ion. Charging batteries to this voltage level has been shown to double cycle life. Lithium-ion systems for defense applications make use of the lower voltage threshold. The negative is a much lower capacity.

-The charge current of Li-ion should be moderate (0.5C for cobalt-based lithium-ion). The lower charge current reduces the time in which the cell resides at 4.20V. A 0.5C charge only adds marginally to the charge time over 1C because the topping charge will be shorter. A high current charge tends to push the voltage into voltage limit prematurely.

-Do not discharge lithium-ion too deeply. Instead, charge it frequently. Lithium-ion does not have memory problems like nickel-cadmium batteries. No deep discharges are needed for conditioning.

-Do not charge lithium-ion at or below freezing temperature. Although accepting charge, an irreversible plating of metallic lithium will occur that compromises the safety of the pack.
Not only does a lithium-ion battery live battery for Vostro 1400 longer with a slower charge rate; moderate discharge rates also help. Figure 5 shows the cycle life as a function of charge and discharge rates. Observe the improved laboratory performance on a charge and discharge rate of 1C compared to 2 and 3C.

The commercial cells use a separator/ electrolyte membrane

January 14 [Mon], 2013, 15:35
The lithium-polymer differentiates itself from conventional battery systems in the type of electrolyte used. The original design, dating back to the 1970s, uses a dry solid polymer electrolyte. This electrolyte resembles battery for Vostro 1320 batterya plastic-like film that does not conduct electricity but allows ions exchange (electrically charged atoms or groups of atoms). The polymer electrolyte replaces the traditional porous separator, which is soaked with electrolyte.

The dry polymer design offers simplifications with respect to fabrication, ruggedness, safety and thin-profile geometry. With a cell thickness measuring as little as one millimeter (0.039 inches), equipment designers are left to their own imagination in terms of form, shape and size.

Unfortunately, the dry lithium-polymer suffers from poor conductivity. The internal resistance is too high and cannot deliver the current bursts needed to power modern communication devices and spin up the hard drives of mobile computing equipment. Heating the cell to 60°C (140°F) and higher increases the conductivity, a requirement that is unsuitable for portable applications.

To compromise, some gelled electrolyte has been added. The commercial cells use a separator/ electrolyte membrane prepared from the same traditional porous polyethylene or polypropylene separator filled with a polymer, which gels upon filling with the liquid electrolyte. Thus the commercial lithium-ion polymer cells are very similar in chemistry and materials to their liquid electrolyte counter parts.

Lithium-ion-polymer has not caught on as quickly as some analysts had expected. Its superiority to other systems and low battery for Inspiron-1320manufacturing costs has not been realized. No improvements in capacity gains are achieved - in fact, the capacity is slightly less than that of the standard lithium-ion battery. Lithium-ion-polymer finds its market niche in wafer-thin geometries, such as batteries for credit cards and other such applications.

Lithium-ion (Li-ion) batteries typically have

November 28 [Wed], 2012, 11:16
The life of your battery will vary depending on the product configuration, product model, applications loaded on the product, power management settings of the product, and the product features used by the customer. As with allreplacement battery for Inspiron 1521 battery, the maximum capacity of your battery will decrease with time or use.

All rechargeable batteries gradually lose their capacity to hold a charge. The battery cycle life is the total number of charge cycles a battery supplies before it can no longer hold a useful amount of charge.

This loss in capacity (aging) is irreversible and cannot be restored. Gradually, less and less active material is available within each cell to electrochemically store a charge. Consequently, the battery provides less useable Dell Vostro 1400 laptop batterytime to power the computer.

Lithium-ion (Li-ion) batteries typically have a lifespan of between 300 and 500 cycles. With moderate use, Lithium-ion batteries can be expected to deliver around 80% of their original capacity after 300 cycles or about one year of use (see graph above).

The smallest battery in the world measures

November 28 [Wed], 2012, 11:15
We know that a battery is a device that converts chemical energy into electrical energy. Batteries have two electrodes, an anode (the negative end) and a cathode (the positive end). Collectively the anode and the cathode are called the electrodes. What is positve and what is the negative terminal? It would be great to simply say that the anode is negative and the cathode is positive, however, that is not always the case. Somtimes the opposite is true depending on battery technology.

In between the battery’s two electrodes runs an electrical current caused primarily from a voltage differential between the anode and cathode. The voltage runs through a chemical called an electrolyte (which can be either liquid or solid). We also know many attributes about batteries the different types of voltage, capacity, chemical make-up and other technical aspects.

But one fascinating consideration that is fun to look at has nothing really to do with the technical ratings, or how long a battery can power a PDA or other device for, or any other technical feature. It is perhaps more journalistic in nature, more inquisitive, more to do with interesting little facts then anything else!

So let’s dive into this fact finding article and discover some of the hidden facts about batteries:

When was the first battery made and who made the first battery?

The first inclination that an electrical path-way from an anode to a cathode within a battery or in this first instance “a frog” occurred in 1786, when Count Luigi Galvani (an Italian anatomist, 1737-1798) found that when the muscles of a dead frog were touched by two pieces of different metals, the muscle tissue twitched.

This led to idea by Count Alessandro Giuseppe Antonio Anastasio Volta (Feb. 18, 1745- March 5, 1827), an Italian physicist who realized that the twitching was caused by an electrical current that was created by chemicals. Volta’s discovery led to the invention of the chemical battery (also called the voltaic pile) in 1800. His first voltaic piles were made from zinc and silver plates (separated by a cloth) put in a salt water bath (brine). Volta improved the pile, using zinc and copper in a weak sulfuric acid bath and thus invented the first generator of continuous electrical current.

How many batteries are there in the world today?

If you take into consideration every conceivable place a battery can be used it is highly probable that the number would be hundreds of billions. That number of batteries would shrink if you start including certain parameters that would further qualify a family or group of batteries. But without question a lot: children toys, gaming machines, digital cameras, hearing aids, watches, computers, cars. When you start thinking in the broadest possible sense there are quite a bit of batteries being used in the world today.

What is the biggest battery in the world?

ABB, the global power and automation technology group, built the world’s largest battery energy storage system in Fairbanks Alaska. The energy storage system includes a massive nickel-cadmium battery, power conversion modules, metering, protection and control devices and service equipment. This battery provides continuous voltage support during normal operation, as well as energy back-up - to quickly provide power during system disturbances. The battery’s purpose is to be used as an electrical bridge during emergency power outages for customers of the Golden Valley Electric Association Inc (GVEA) in Fairbanks, Alaska.

In operation, the battery will produce power for several minutes to cover the time between a system disturbance and when the utility company is able to bring back-up generation on line. The battery is a high performance nickel-cadmium storage battery made up of 13,760 energy cells. Each cell measures 16 in. by 21 in. This NiCad battery is approximately 21,520 square feet in size and weighs approximately 2,866,009. This big battery provides 40 megawatts of power - enough electricityrn873 Vostro 1710 battery
for 12,000 people - for up to seven minutes.

What is the smallest battery in the world?

The smallest battery in the world measures 2.9 mm in diameter and 13 mm in length (about the size of a pencil tip). The cylindrical device is only 1/35 the size of a standard AA battery. The battery can, with recharging, last up to 10 years. The battery is made of a polysiloxane polymer, a material that has the highest conductivity ever reported for an electrical conductor. Recharging the battery is done wirelessly by an external electrical field, which is of great benefit since these batteries are designed to stimulate damaged nerves and muscles inside the human body.

Tests of replicas, when filled with an acidic liquid

October 10 [Wed], 2012, 12:11
Why was a battery required 2000 years ago?
In June, 1936, workers constructing a new railway near the city of Baghdad uncovered an ancient tomb. Relics in the tomb allowecheap AS10B31d archeologists to identify it as belonging to the Parthian Empire. The Parthians, although illiterate and nomadic, were the dominating force in the Fertile Crescent area between 190 BC to 224 AD. It is known that in 129 BC they had acquired lands up to the banks of the Tigris River, near Baghdad.

Among the relics found in the tomb was a clay jar or vase, sealed with pitch at its top opening. An iron rod protruded from the center, surrounded by a cylindrical tube made of wrapped copper sheet. The height of the jar was about 15 cm, and the copper tube was about 4 cm diameter by 12 cm in length. Tests of replicas, when filled with an acidic liquid such as vinegar, showed it could have produced between 1.5 and 2 volts between the iron and copper. It is suspected that this early Acer rn873 AS10D61, or more than one in series, may have been used to electroplate gold onto silver artifacts.

A German archeologist, Dr. Wilhelm Konig, identified the clay pot as a possible battery in 1938. While its 2000-year old date would make it the first documented battery invention, there may have been even earlier technology at work. Dr. Konig also found Sumerian vases made of copper, but plated with silver, dating back to 2500 BC. No evidence of Sumerian batteries has been found to date.

The case has been redesigned to allow easy one-handed access to the batteries

October 10 [Wed], 2012, 12:10
There have been many more failures than successes along the road to developing a good charger. Products were announced, and then you didn't see any more of them. The reason is simple -- they didn't work. One came high quality UM09A41close to working, the Buddy-L SuperCharger, announced in 1993. Popular Science magazine named it as one of the 100 top scientific achievements of the year.

But it did not live up to expectations. Apparently, the product was launched into production too quickly, and sub-standard operation resulted. Fortunately, the problems did not hurt the batteries.

The batteries simply switched off prematurely before charging was complete, and the users had to restart the charging process several times. Also, it was not designed for easy battery insertion, always requiring two hands and a struggle. Eleven years later, many people are still using their SuperChargers cheap UM09A31and are reluctant to part with them.

All the background information was absorbed and a totally re-engineered product emerged, the Battery Xtender ™ Tests have shown that it does live up to expectations, and that the claims of ten times life extension for ordinary alkaline batteries are not exaggerated. The case has been redesigned to allow easy one-handed access to the batteries, and it occupies much less space on a desk, table top or counter.