To estimate capacity and state-of-charge on the fly

June 17 [Mon], 2013, 12:25
The resistance of a battery provides useful information about its performance and detects hidden trouble spots. High resistance values are often the triggering point to replace an aging battery, and determining resistance is especially useful in checking stationary batteries. However, resistance comparison alone is not AS07A71 replacement effective, because the value between batches of lead acid batteries can vary by eight percent. Because of this relatively wide tolerance, the resistance method only works effectively when comparing the values for a given battery from birth to retirement. Service crews are asked to take a snapshot of each cell at time of installation and then measure the subtle changes as the cells age. A 25 percent increase in resistance over the original reading hints to an overall performance drop of 20 percent.

Manufacturers of stationary batteries typically honor the warranty if the internal resistance increases by 50 percent. Their preference is to get true capacity readings by applying a full discharge. It is their belief that only a discharge can provide reliable readings and they ask users to perform the service once a year. While this advice has merit, a full discharge requires a temporary disconnection of the battery from the system, and on a large battery such a test takes an entire day to complete. In the real world, very few battery installations receive this type of service and most measurements are based on battery resistance readings.

Measuring the internal resistance is done by reading the voltage drop on a load current or by AC impedance. The results are in ohmic values. There is a notion that internal resistance is related to capacity, and this is false. The resistance of many AS07B71 replacementstays flat through most of the service life.


To estimate capacity and state-of-charge on the fly involves impedance trending by scanning a battery with frequencies ranging from less than one hertz to several thousand hertz. Read more about Testing Lead Acid Batteries.

As doctors will examine a patient with different devices

June 17 [Mon], 2013, 12:22
A German manufacturer of luxury cars points out that one out of two starter batteries returned under warranty is working and has no problem. It is possible that battery testers used in service garages did not detect the Acer AS10D75 replacementcorrectly before they were returned under warranty. ADAC* reported in 2008 that 40 percent of all roadside automotive failures are battery-related. In Japan, battery failure is the largest single complaint among new car owners.

The average car is driven 13km (8 miles) per day and mostly in congested cities. The most common reason for battery failure is undercharge. Battery performance is important; problems during the warranty period tarnish customer satisfaction.
Battery malfunction during the warranty period is seldom a factory defect; driving habits are the culprits. A manufacturer of German-made starter batteries stated that factory defects account for only 5 to 7 percent of warranty claims. The battery remains a weak link, and is evident when reviewing the ADAC 2008 report for the year 2007. The study examines the breakdowns of 1.95 million vehicles six years old or less, and Table 1 provides the reasons.

The cellular phone industry experiences an even more astonishing battery return pattern. Nine out of 10 batteries returned under warranty have no problem or can easily be serviced. This is no fault of the manufacturers but they pay a price that is ultimately charged to the user.

Part of the problem lies in the difficulty of testing batteries at the consumer level, and this applies to storefronts and service garages alike. Battery rapid-test methods seem to dwell in medieval times, and this is especially evident when comparing advancements made on other fronts. We don’t even have a reliable method to estimate state-of-charge — most of such measurements using voltage and coulomb counting are guesswork. Assessing capacity, the most reliable health indicator of a battery, dwells far behind.
The battery user may ask why the industry is lagging so far behind. The answer is simple: battery testing and monitoring is far more complex than outsiders perceive it. As there is no single diagnostic device that can assess the health of a person, so are there no instruments that can quickly check the state-of-health of a battery. Like the human body, batteries can have many hidden deficiencies that no single tester is able to identify with certainly. Yes, we can apply a discharge, but this takes the AL10C31 replacement out of service and induces stress, especially on large systems. In some cases, even a discharge does not provide conclusive results either. Read more about Discharge Methods.


As doctors will examine a patient with different devices, so also does a battery need several approaches to find anomalies. A dead battery is easy to measure and all testers can do this. The challenge comes in evaluating a battery in the 80 to 100 percent performance range. This chapter examines current and futuristic methods and how they stand up. One thing to remember is this: batteries cannot be measured; the appropriate instruments can only make predictions or estimations. This is synonymous with a doctor examining a patient, or the weatherman predicting the weather. All findings are estimations with various degrees of accuracies.

A pack can get destroyed within a few short seconds

April 27 [Sat], 2013, 15:11
With the high usage of lithium-ion in cell phones, digital cameras and laptops, there are bound to be issues. A one-in-200,000 failure rate triggered a recall of almost six million lithium-ion packs used in laptops manufactured by Dell and Apple. Heat related battery failures are taken very seriously and manufacturers Vostro 1400 laptop battery chose a conservative approach. The decision to replace the batteries puts the consumer at ease and lawyers at bay. Let's now take a look at what's behind the recall.

Sony Energy Devices (Sony), the maker of the lithium-ion cells in question, says that on rare occasions microscopic metal particles may come into contact with other parts of the battery cell, leading to a short circuit within the cell. Although battery manufacturers strive to minimize the presence of metallic particles, complex assembly techniques make the elimination of all metallic dust nearly impossible.

A mild short will only cause an elevated self-discharge. Little heat is generated because the discharging energy is very low. If, however, enough microscopic metal particles converge on one spot, a major electrical short can develop and a sizable current will flow between the positive and negative plates. This causes the temperature to rise, leading to a thermal runaway, also referred to 'venting with flame.'

Lithium-ion cells with cobalt cathodes (same as the recalled laptop batteries) should never rise above 130°C (265°F). At 150°C (302°F) the cell becomes thermally unstable, a condition that can lead to a thermal runaway KM742 laptop battery in which flaming gases are vented.

During a thermal runaway, the high heat of the failing cell can propagate to the next cell, causing it to become thermally unstable as well. In some cases, a chain reaction occurs in which each cell disintegrates at its own timetable. A pack can get destroyed within a few short seconds or linger on for several hours as each cell is consumed one-by-one. To increase safety, packs are fitted with dividers to protect the failing cell from spreading to neighboring cells.

Lithium-ion batteries are nearing their theoretical energy

April 27 [Sat], 2013, 15:07
When Sony introduced the first lithium-ion battery in 1991, they knew of the potential safety risks. A recall of the previously released rechargeable metallic lithium battery was a bleak reminder of the discipline one must exercise Inspiron-1320 laptop batterywhen dealing with this high energy-dense battery system.

Pioneering work for the lithium battery began in 1912, but is was not until the early 1970's when the first non-rechargeable lithium batteries became commercially available. Attempts to develop rechargeable lithium batteries followed in the eighties. These early models were based on metallic lithium and offered very high energy density. However, inherent instabilities of lithium metal, especially during charging, put a damper on the development. The cell had the potential of a thermal run-away. The temperature would quickly rise to the melting point of the metallic lithium and cause a violent reaction. A large quantity of rechargeable lithium batteries had to be recalled in 1991 after the pack in a cellular phone released hot gases and inflicted burns to a man's face.

Because of the inherent instability of lithium metal, research shifted to a non-metallic lithium battery using lithium ions. Although slightly lower in energy density, the lithium-ion system is safe, providing certain precautions are met when charging and discharging. Today, lithium-ion is one of the most successful and safe battery chemistries available. Two billion cells are produced every year.

Lithium-ion cells with cobalt cathodes hold twice the energy of a nickel-based battery and four-times that of lead acid. Lithium-ion is a low maintenance system, an advantage that most other chemistries cannot claim. There is no memory and the battery does not require scheduled cycling to prolong its life. Nor does lithium-ion have the sulfation problem of lead acid that occurs when the battery is stored without periodic topping charge. Lithium-ion has a low self-discharge and is environmentally friendly. Disposal causes minimal harm.

Long battery runtimes have always been the wish of many consumers. Battery manufacturers responded by packing more active material into a cell and making the electrodes and separator thinner. This enabled a doubling of energy density since lithium-ion was introduced in 1991.

The high energy density comes at a price. Manufacturing methods become more critical the denser the cells become. With a separator thickness of only 20-25µm, any small intrusion of metallic dust particles can have devastating consequences. Appropriate measures will be needed to achieve the mandated safety Vostro 1710 laptop batterystandard set forth by UL 1642.

Whereas a nail penetration test could be tolerated on the older 18650 cell with a capacity of 1.35Ah, today's high-density 2.4Ah cell would become a bomb when performing the same test. UL 1642 does not require nail penetration. Lithium-ion batteries are nearing their theoretical energy density limit and battery manufacturers are beginning to focus on improving manufacturing methods and increasing safety.

The battery is an elusive scapegoat

March 18 [Mon], 2013, 15:39
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 Falklandreplacement 593562-001s War in 1982 on account of uncooperative batteries.

The officers assumed that a battery 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 thereplacement 537627-001manufacturer for failing to deliver the specified battery performance, even when human lives are at stake. Less critical failures have been debated in court and punished 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.

Ignoring the performance criteria of a battery nullifies

March 18 [Mon], 2013, 15:29
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 andreplacement HSTNN-DB73 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. The battery as power source is seen as a black box, and for some inspectors correct size, weight and color satisfies the replacement 497694-001requirements. 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.

Even auditors of quality-control systems shy away from the battery

March 18 [Mon], 2013, 15:26
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 battery would alwreplacement 593550-001ays 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 specifiedreplacement Pavilion probook 4710s batteryperformance, even when human lives are at stake. Less critical failures have been debated in court and punished 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.

Some battery manufacturers add an end-of-battery-life

March 18 [Mon], 2013, 15:24
Most laptop batteries are smart. This means that the pack consists of two parts: the chemical cells and the digital circuit. If the cells are weak, cell replacement makes economic sense. While nickel-based cells are readily available, lithium-ion cells are commonly not sold over the counter, and most manufacturers replacement Pavilion envy 17 batteryonly offer them to authorized pack assemblers. This precaution is understandable given liability issues. Read also about Safety Concerns and Protection Circuits. Always use the same chemistry; the mAh rating can vary if all cells are replaced.

A laptop battery may have only one weak cell, and the success rate of replacing the affected cell depends on the matching with the others. All cells in a pack must have a similar capacity because an imbalance shortens the life of the pack. Read more about Can Batteries Be Restored?. Furthermore, the state-of-charge of all cells being charged for the first time should have a similar charge level, and the open-circuit voltages should be within 10 percent of each other. Welding the cells is the only reliable way to get dependable connection. Limit the heat transfer to the cells during welding to prevent excess heat buildup.

The typical SMBus battery has five or more battery connections consisting of positive and negative battery terminals, thermistor, clock and data. The connections are often unmarked; however, the positive and negative are commonly located at the outer edges of the connector and the inner contacts accommodate the clock and data. (The one-wire system combines clock and data.) For safety reasons, a separate thermistor wire is brought to the outside. Figure 1 illustrates a battery with six connections.

Some batteries are equipped with a solid-state switch that is normally in the “off” position and no voltage is present on the battery terminals; connecting the switch terminal to ground often turns the battery on. If this does not work, the pack may need a proprietary code for activation, and battery manufacturers keep these codes a well-guarded secret.

How can you find the correct terminals? Use a voltmeter to locate the positive and negative battery terminals and establish the polarity. If no voltage is available, a solid-state switch in the “off” position may need activating. Connecting the voltmeter to the outer terminals, take a 100-Ohm resistor (other values may also work), tie one end to ground, and with the other end touch each terminal while observing the voltmeter. If no voltage appears, the battery may be dead or the pack will require a security code. The 100-Ohm resistor is low enough to engage a digital circuit and high enough to protect the battery against a possible electrical short.

Establishing the connection to the battery terminals should now enable charging. If the charge current stops after 30 seconds, an activation code may be required, and this is often difficult if not impossible to obtain.

Some battery manufacturers add an end-of-battery-life switch that turns the battery off when reaching a certain age or cycle count. Manufacturers argue that customer satisfaction and safety can only be guaranteed by regularly replacing the battery. Such a policy tends to satisfy the manufacturer more than the user, and newer batteries do not include this feature.

If at all possible, connect the thermistor during charging and discharging to protect the battery against possible overheating. Use an ohmmeter to locate the internal thermistor. The most common thermistors are 10 Kilo Ohm NTC, which reads 10kΩ at 20°C (68°F). NTC stands for negative temperature coefficient, meaning that the resistance decreases with rising temperature. In comparison, a positive temperature coefficient (PTC) causes the resistance to increase. Warming the battery with your hand may be sufficient to detect a small change in resistor value when looking for the correct terminal on the battery.

In some cases the chemical battery can be restored, but the fuel gauge might not work, is inaccurate, or will provide wrong information. After repackaging, the battery may need some sort of initialization/ calibration process. Simply charging and discharging the pack to reset the flags might do the trick. A “flag” is a measuring point to mark and record an event.

The circuits of some smart batteries must be kept alive during cell replacement. Disconnecting the voltage for only a fraction of a second can erase vital data in the memory. The lost data could contain the resistor value of the digitized shunt that is responsible for the coulomb counter. Some integrated circuits (IC) responsible for fuel gauge function have wires going to each cell, and the sequence of assembly must to be done in the correct order.

To assure continued operation when changing the cells, supply a secondary voltage through a 100-Ohm resistor to the circuit before disconnection and remove the supply only after the circuit receives voltage againreplacement Pavilion g6 battery from the new cells. Cell replacement of a smart battery has a parallel with open-heart surgery, where doctors must keep all organs of the patient alive.

Anyone repairing an SMBus battery needs to be aware of compliance issues. Unlike other tightly regulated standards, the SMBus allows some variations, and this can cause problems when matching battery packs with existing chargers. The repaired SMBus battery should be checked for compatibility before use.

These cells come at a higher cost in terms of stored energy

January 14 [Mon], 2013, 15:25
Pioneer work with the lithium battery began in 1912 under G.N. Lewis but it was not until the early 1970s when the first non-rechargeable lithium batteries became commercially available. lithium is the lightest of all metals, has battery for envy T117Cthe greatest electrochemical potential and provides the largest energy density for weight.

Attempts to develop rechargeable lithium batteries failed due to safety problems. Because of the inherent instability of lithium metal, especially during charging, research shifted to a non-metallic lithium battery using lithium ions. Although slightly lower in energy density than lithium metal, lithium-ion is safe, provided certain precautions are met when charging and discharging. In 1991, the Sony Corporation commercialized the first lithium-ion battery. Other manufacturers followed suit.

The energy density of lithium-ion is typically twice that of the standard nickel-cadmium. There is potential for higher energy densities. The load characteristics are reasonably good and behave similarly to nickel-cadmium in terms of discharge. The high cell voltage of 3.6 volts allows battery pack designs with only one cell. Most of today's mobile phones run on a single cell. A nickel-based pack would require three 1.2-volt cells connected in series.

Lithium-ion is a low maintenance battery, an advantage that most other chemistries cannot claim. There is no memory and no scheduled cycling is required to prolong the battery's life. In addition, the self-discharge is less than half compared to nickel-cadmium, making lithium-ion well suited for modern fuel gauge applications. lithium-ion cells cause little harm when disposed.

Despite its overall advantages, lithium-ion has its drawbacks. It is fragile and requires a protection circuit to maintain safe operation. Built into each pack, the protection circuit limits the peak voltage of each cell during charge and prevents the cell voltage from dropping too low on discharge. In addition, the cell temperature is monitored to prevent temperature extremes. The maximum charge and discharge current on most packs are is limited to between 1C and 2C. With these precautions in place, the possibility of metallic lithium plating occurring due to overcharge is virtually eliminated.

Aging is a concern with most lithium-ion batteries and many manufacturers remain silent about this issue. Some capacity deterioration is noticeable after one year, whether the battery is in use or not. The battery frequently fails after two or three years. It should be noted that other chemistries also have age-related degenerative effects. This is especially true for nickel-metal-hydride if exposed to high ambient temperatures. At the same time, lithium-ion packs are known to have served for five years in some applications.

Manufacturers are constantly improving lithium-ion. New and enhanced chemical combinations are introduced every six months or so. With such rapid progress, it is difficult to assess how well the revised battery will age.

Storage in a cool place slows the aging process of lithium-ion (and other chemistries). Manufacturers recommend storage temperatures of 15°C (59°F). In addition, the battery should be partially charged during storage. The battery for KY265 manufacturer recommends a 40% charge.

The most economical lithium-ion battery in terms of cost-to-energy ratio is the cylindrical 18650 (size is 18mm x 65.2mm). This cell is used for mobile computing and other applications that do not demand ultra-thin geometry. If a slim pack is required, the prismatic lithium-ion cell is the best choice. These cells come at a higher cost in terms of stored energy.

Li-ion the universally acceptable battery for portable application

January 14 [Mon], 2013, 15:20
It was not until the early 1970s that the first non-rechargeable lithium batteries became commercially available. Attempts to develop battery for Studio 1535 batteryrechargeable lithium batteries followed in the 1980s but the endeavor failed because of instabilities in the metallic lithium used as anode material.

Lithium is the lightest of all metals, has the greatest electrochemical potential and provides the largest specific energy per weight. Rechargeable batteries with lithium metal on the anode (negative electrodes) could provide extraordinarily high energy densities, however, cycling produced unwanted dendrites on the anode that could penetrate the separator and cause an electrical short. The cell temperature would rise quickly and approaches the melting point of lithium, causing thermal runaway, also known as “venting with flame.”

The inherent instability of lithium metal, especially during charging, shifted research to a non-metallic solution using lithium ions. Although lower in specific energy than lithium-metal, Li-ion is safe, provided cell manufacturers and battery packers follow safety measures in keeping voltage and currents to secure levels. In 1991, Sony commercialized the first Li-ion battery, and today this chemistry has become the most promising and fastest growing on the market. Meanwhile, research continues to develop a safe metallic lithium battery in the hope to make it safe.

In 1994, it cost more than $10 to manufacture Li-ion in the 18650* cylindrical cell delivering a capacity of 1,100mAh. In 2001, the price dropped to $2 and the capacity rose to 1,900mAh. Today, high energy-dense 18650 cells deliver over 3,000mAh and the costs have dropped further.

Cost reduction, increase in specific energy and the absence of toxic material paved the road to make Li-ion the universally acceptable battery for portable application, first in the consumer industry and now increasingly also in heavy industry, including electric powertrains for vehicles.

In 2009, roughly 38 percent of all batteries by revenue were Li-ion. Li-ion is a low-maintenance battery, an advantage many other chemistries cannot claim. The battery has no memory and does not need exercising to keep in battery for T112Cshape. Self-discharge is less than half compared to nickel-based systems.

This makes Li-ion well suited for fuel gauge applications. The nominal cell voltage of 3.6V can power cell phones and digital cameras directly, offering simplifications and cost reductions over multi-cell designs. The drawback has been the high price, but this leveling out, especially in the consumer market.
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