Many people request me whether replace a keyboard is possible. Yes. it is possible to replace individual keys on your laptop's keyboard! Note that the same laptop model can have several different types of hinge mechanisms under the key. Some colors in the pictures may differ for your model. That is fine, what matters most is the shape of the hinge piece. Now, there is a guide to repairing your laptop or notebook's keyboard Step 1: Orient the hinge The plastic hinge mechanism must be oriented as shown for it to fit onto the metal keyboard hooks. Step 2: Hook the hinge onto the base Hook the inner top edge of the hinge over the top metal hook on the base of the keyboard. Step 3: Secure the hinge into place Snap the bottom of the hinge into place, one side at a time. This may take a bit of pressure. In this example, the bottom right side is being secured first. The bottom right and left sides of the plastic hinge should be clipped between the two metal notches protruding from the base of the keyboard on each side. You can now check that the hinge works by flexing it up and down; it should pivot easily at it's axis. Step 4: Press the key into place Align the key on top of its place on the keyboard, and press down evenly. All four corners of the key should click into place. Acer TravelMate 2303 Battery(ssa)
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A modern battery is a delicate storage device that requires protection to safeguard against damage. The most basic protection is a fuse that opens on excess current. Some fuses disengage permanently and render the battery useless once the filament is broken; other safety devices are resettable. The Polyswitch™ is such a resettable fuse. Connected into the battery's current path, this device creates a high resistance on excess current. The Polyswitch™ reverts to the low ON position when the condition normalizes, allowing operation to resume. Batteries used in hazardous areas must be intrinsically safe. Hazardous areas include oil refineries, mines, grain elevators and fuel handling at airports. These areas are typically serviced with two-way radios and computing devices. Intrinsically safe batteries prevent excessive heat buildup and the danger of an electric spark on equipment failure. Because of tight approval standards, intrinsically safe batteries carry twice to three-times the price tag of regular packs. Another battery that contains high-level protection is lithium-ion. This is done to assure safety under all circumstances while in the hands of the public. Typically, a Field Effect Transistor (FET) opens if the charge voltage of any cell reaches 4.30V. A separate fuse opens if the cell temperature approaches 90°C (194°F). In addition, a disconnect switch in each cell permanently interrupts the charge current if a safe pressure threshold of about 10 Bar (150 psi) is exceeded. To prevent the battery from over-discharging, the control circuit cuts off the current path at about 2.50V/cell. Prolonged storage at voltages of 1.5V/cell and lower damages the lithium-ion, causing safety problems if attempted to recharge. Each parallel string of cells in a lithium-ion pack needs independent voltage monitoring. In addition, each cell in series must be monitored for voltage. The more cells that are connected in series, the more complex the protection circuit becomes. Four cells in series is the practical limit for commercial applications. The internal protection circuit must be designed to add as little resistance as possible to the current path. The circuit of a cell phone battery often consists of two FET switches connected in series. One FET is responsible for high, the other for low voltage cut-off. The combined resistance of the FETs in the ON position is 50-100milli Ohms (mW). This virtually doubles the internal resistance of a battery pack. A major concern arises if static electricity or a faulty charger destroys the battery's protection circuit. This may result in permanently fusing the solid-state switches in an ON position without the user's knowledge. A battery with a faulty protection circuit may function normally but will not provide protection. If charged over a voltage limit (4.20V/cell should not be exceeded) with a defective charger, venting with flame could occur. Such a situation must be avoided at all cost. Shorting such a battery could also be hazardous. Low-cost cell phone batteries have infiltrated the world market since the beginning of 2003,. These counterfeit batteries often do not have an approved protection circuit and can vent with flame if the charger malfunctions. Cell phone manufacturers strongly advise customers to replace the battery with an approved brand. Failing to do so may void the warranty. It is also highly recommended to only use approved chargers. (See photos of an exploded cell phone with a clone battery that was on charge.) When advising on the choice of batteries and chargers, cell phone manufacturers act out of genuine concern for safety rather than using scare tactics to persuade customers to buy their own accessories. They do not object third parties as long as the products are well built and safe. The buyer can often not distinguish between an original and a counterfeit battery because the label may appear bona fide. Small lithium-ion packs with spinel (manganese) chemistry containing one or two cells may only include a fuse as protection. Spinel is more tolerant to abuse than cobalt and the cells are deemed safe if below a certain size. Although less expensive, the absence of a protection circuit introduces a new problem. Cell phone users have access to low-cost chargers that may rely on the battery's protection circuit to terminate charge. Without the protection circuit, the cell voltage rises too high and damages the battery. Excess heat, even bulging can result. Discontinue using the battery and charger if a lithium-ion battery gets hot. To maintain safe operation, manufacturers do not sell the lithium-ion cells by themselves but make them available in a battery pack, complete with protection circuit. The circuit is often subject to exact scrutiny before the manufacturers release cells to the pack assemblers. Although there are a few reported incidents of venting with flame, the lithium-ion battery is safe.

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An LCD that can show colors must have three subpixels with red, green and blue color filters to create each color pixel. Through the careful control and variation of the voltage applied, the intensity of each subpixel can range over 256 shades. Combining the subpixels produces a possible palette of 16.8 million colors (256 shades of red x 256 shades of green x 256 shades of blue), as shown below. These color displays take an enormous number of transistors. For example, a typical laptop computer supports resolutions up to 1,024x768. If we multiply 1,024 columns by 768 rows by 3 subpixels, we get 2,359,296 transistors etched onto the glass! If there is a problem with any of these transistors, it creates a "bad pixel" on the display. Most active matrix displays have a few bad pixels scattered across the screen. LCD technology is constantly evolving. LCDs today employ several variations of liquid crystal technology, including super twisted nematics (STN), dual scan twisted nematics (DSTN), ferroelectric liquid crystal (FLC) and surface stabilized ferroelectric liquid crystal (SSFLC). Display size is limited by the quality-control problems faced by manufacturers. Simply put, to increase display size, manufacturers must add more pixels and transistors. As they increase the number of pixels and transistors, they also increase the chance of including a bad transistor in a display. Manufacturers of existing large LCDs often reject about 40 percent of the panels that come off the assembly line. The level of rejection directly affects LCD price since the sales of the good LCDs must cover the cost of manufacturing both the good and bad ones. Only advances in manufacturing can lead to affordable displays in bigger sizes. For more information on LCDs and related topics, check out the links on the next page.

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Symptoms If some or all of the keys on your Apple keyboard don't seem to be working, use these tips to troubleshoot the issue. Products Affected Keyboards, Mac OS X 10.4, Mac OS X 10.3, Mac OS X 10.2, Mac OS X 10.1, Mac OS X 10.0, Mac OS X 10.5 Resolution No keys work (external keyboard)  Disconnect and reconnect your keyboard if it is external. Make sure that the connector is completely inserted into the port. (USB plugs fit into ports one way only, and won't allow you to make a connection if you try to connect them in upside-down.) Test the keyboard again.  Connect your keyboard to a different USB port.  Try a different keyboard on your computer if possible, or your keyboard on a different Mac. Portable Mac's built-in keyboard only produces numbers (MacBook, MacBook Pro)  Make sure the Num Lock key is off, or not active. Some keys don't work as expected 1. Open Speech preferences in System Preferences. If "Speak selected text when the key is pressed" is enabled, the key combination to speak text cannot be used for other purposes or used to type text--change to a more obscure key combination (try to use more modifier keys such as Shift, Command, Option, and Control). Or, simply disable the "Speak selected text when the key is pressed" option. 2. Open Universal Access preferences in System Preferences, click the Keyboard tab, and make sure that Slow Keys is turned off. With Slow Keys on, you need to press a key for a longer period of time for it to be recognized. 3. In Universal Access preferences, click the Mouse tab, and make sure Mouse Keys is turned off. With Mouse Keys enabled, you cannot use the Numeric Keypad to enter numbers--instead the keypad moves the pointer (cursor). (There is an option to enable Mouse Keys with five presses of the Option key; you may want to turn that option off to avoid accidentally enabling it.) 4. If the issue persists, open System Preferences and click International. 5. Click the Input Menu tab. 6. Click the Keyboard Viewer "On" checkbox to select it. 7. From the Input (flag) menu, choose Show Keyboard Viewer. 8. If the keyboard is connected and detected by Mac OS X, the keys you type will highlight in the Keyboard Viewer window. Try typing to see which keys are not highlighting in Keyboard Viewer. 9. Open TextEdit (or another text application) and try to type something using the keys that were previously not responding.

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Microsoft Windows users can enable the accessibility feature to move the mouse using their arrow keys by following the below steps. 1. Click Start, Settings, Control Panel. 2. Within the Control Panel open "Accessibility Options" 3. Click the Mouse tab. 4. Check the "Use Mouse Keys" check box. 5. If you wish to increase the speed or change any other settings, click on the Settings button. 6. Click Apply and then close out of the box. After performing the above steps you will be able to used the numeric keypad as a mouse moving up, down, left, right, and all the diagonals. In addition, you may also use the center "5" key as a left click. Note: You must have the Number lock on for this feature to work by default. This can be changed through the settings. Laptop keyboard(Brand new )
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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 when 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 standard 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. Recall of lithium-ion batteries 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 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 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. Safety level of lithium-ion systems 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 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 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. What every battery user should know A major concern arises if static electricity or a faulty charger has destroyed the battery's protection circuit. Such damage can permanently fuse the solid-state switches in an ON position without the user knowing. A battery with a faulty protection circuit may function normally but does not provide protection against abuse. Another safety issue is cold temperature charging. Consumer grade lithium-ion batteries cannot be charged below 0°C (32°F). Although the packs appear to be charging normally, plating of metallic lithium occurs on the anode while on a sub-freezing charge. The plating is permanent and cannot be removed. If done repeatedly, such damage can compromise the safety of the pack. The battery will become more vulnerable to failure if subjected to impact, crush or high rate charging. Asia produces many non-brand replacement batteries that are popular with cell phone users because of low price. Many of these batteries don't provide the same high safety standard as the main brand equivalent. A wise shopper spends a little more and replaces the battery with an approved model. Figure 1 shows a cell phone that was destroyed while charging in a car. The owner believes that a no-name pack caused the destruction. Figure 2: A cell phone with a no-brand battery that vented with flame while charging in the back of a car. To prevent the infiltration of unsafe packs on the market, most manufacturers sell lithium-ion cells only to approved battery pack assemblers. The inclusion of an approved safety circuit is part of the purchasing requirement. This makes it difficult for a hobbyist to purchase single lithium-ion cells off-the-shelf in a store. The hobbyist will have no other choice than to revert to nickel-based batteries. I would caution against using an unidentified lithium-ion battery from an Asian source, if such cells is available. The safety precaution is especially critical on larger batteries, such as laptop packs. The hazard is so much greater than on a small cell phone battery if something goes wrong. For this reason, many laptop manufacturers secure their batteries with a secret code that only the matching computer can access. This prevents non-brand-name batteries from flooding the market. The drawback is a higher price for the replacement battery. Readers of www.BatteryUniversity.com often ask me for a source of cheap laptop batteries. I have to disappoint the shoppers by directing them to the original vendor for a brand name pack. Considering the number of lithium-ion batteries used on the market, this energy storage system has caused little harm in terms of damage and personal injury. In spite of the good record, its safety is a hot topic that gets high media attention, even on a minor mishap. This caution is good for the consumer because we will be assured that this popular energy storage device is safe. After the recall of Dell and Apple laptop batteries, cell manufacturers will not only try packing more energy into the pack but will attempt to make it more bulletproof.

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Each battery system offers unique advantages but none provides a fully satisfactory solution. With the increased selection of battery chemistries available today, better choices can be made to address specific battery needs. A careful evaluation of each battery's attribute is important. Because of similarities, both nickel-cadmium and nickel-metal hydride are covered in this paper. The nickel-cadmium battery Swedish Waldmar Jungner invented the nickel-cadmium battery in 1899. At that time, the materials were expensive compared to other battery types available and its use was limited to special applications. In 1932, the active materials were deposited inside a porous nickel-plated electrode and in 1947 research began on a sealed nickel-cadmium battery. Rather than venting, the internal gases generated during charge were recombined. These advances led to the modern sealed nickel-cadmium battery, which is in use today. Nickel-cadmium prefers fast charge to slow charge and pulse charge to DC charge. It is a strong and silent worker; hard labor poses little problem. In fact, nickel-cadmium is the only battery type that performs well under rigorous working conditions. All other chemistries prefer a shallow discharge and moderate load currents. Nickel-cadmium does not like to be pampered by sitting in chargers for days and being used only occasionally for brief periods. A periodic full discharge is so important that, if omitted, large crystals will form on the cell plates (also referred to as memory) and the nickel-cadmium will gradually lose its performance. Among rechargeable batteries, nickel-cadmium remains a popular choice for two-way radios, emergency medical equipment and power tools. There is shift towards batteries with higher energy densities and less toxic metals but alternative chemistries cannot always match the superior durability and low cost of nickel-cadmium. Here is a summary of the advantages and limitations of nickel-cadmium batteries. Advantages Fast and simple charge, even after prolonged storage. High number of charge/discharge cycles - if properly maintained, nickel-cadmium provides over 1000 charge/discharge cycles. Good load performance - nickel-cadmium allows recharging at low temperatures. Long shelf life - five-year storage is possible. Some priming prior to use will be required. Simple storage and transportation - most airfreight companies accept nickel-cadmium without special conditions. Good low temperature performance. Forgiving if abused - nickel-cadmium is one of the most rugged rechargeable batteries. Economically priced - nickel-cadmium is lowest in terms of cost per cycle. Available in a wide range of sizes and performance options - most nickel-cadmium cells are cylindrical. Limitations Relatively low energy density. Memory effect - nickel-cadmium must periodically be exercised (discharge/charge) to prevent memory. Environmentally unfriendly - nickel-cadmium contains toxic metals. Some countries restrict its use. Relatively high self-discharge - needs recharging after storage The nickel-metal-hydride battery Research on the nickel-metal-hydride system started in the 1970s as a means of storing hydrogen for the nickel hydrogen battery. Today, nickel hydrogen is used mainly for satellite applications. nickel hydrogen batteries are bulky, require high-pressure steel canisters and cost thousands of dollars per cell. In the early experimental days of nickel-metal hydride, the metal hydride alloys were unstable in the cell environment and the desired performance characteristics could not be achieved. As a result, the development of nickel-metal hydride slowed down. New hydride alloys were developed in the 1980s that were stable enough for use in a cell. Since then, nickel-metal hydride has steadily improved. The success of nickel-metal hydride has been driven by high energy density and the use of environmentally friendly metals. The modern nickel-metal hydride offers up to 40% higher energy density compared to the standard nickel-cadmium. There is potential for yet higher capacities, but not without some negative side effects. Nickel-metal hydride is less durable than nickel-cadmium. Cycling under heavy load and storage at high temperature reduces the service life. nickel-metal hydride suffers from high self-discharge, which is higher than that of nickel-cadmium. Nickel-metal hydride has been replacing nickel-cadmium in markets such as wireless communications and mobile computing. Experts agree that nickel-metal hydride has greatly improved over the years, but limitations remain. Most shortcomings are native to the nickel-based technology and are shared with nickel-cadmium. It is widely accepted that nickel-metal hydride is an interim step to lithium-based battery technology. Here is a summary of the advantages and limitations of nickel-metal hydride batteries. Advantages 30-40% higher capacity than standard nickel-cadmium. Nickel-metal-hydride has potential for yet higher energy densities. Less prone to memory than nickel-cadmium - fewer exercise cycles are required. Simple storage and transportation - transport is not subject to regulatory control. Environmentally friendly - contains only mild toxins; profitable for recycling. Limitations Limited service life - the performance starts to deteriorate after 200-300 cycles if repeatedly deeply cycled. Relatively short storage of three years. Cool temperature and a partial charge slows aging. Limited discharge current - although nickel-metal-hydride is capable of delivering high discharge currents, heavy load reduces the battery's cycle life. More complex charge algorithm needed - nickel-metal-hydride generates more heat during charge and requires slightly longer charge times than nickel-cadmium. Trickle charge settings are critical because the battery cannot absorb overcharge. High self-discharge - typically 50% higher than nickel-cadmium. Performance degrades if stored at elevated temperatures - nickel-metal-hydride should be stored in a cool place at 40% state-of-charge. High maintenance - nickel-metal hydride requires regular full discharge to prevent crystalline formation. nickel-cadmium should be exercised once a month, nickel-metal-hydride once in every 3 months.

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Battery novices often brag about miracle batteries that offer very high energy densities, deliver 1000 charge/discharge cycles and are paper-thin. These attributes are indeed achievable but not on one and the same battery pack. A certain battery may be designed for small size and long runtime but has a limited cycle life. Another pack may be built for durability and is big and bulky. A third may have high energy density and long durability but is made for a special application and is too expensive for the average consumer. A lithium-based battery can be designed for maximum energy density but its safety would be compromised. Battery manufacturers are aware of customer needs and offer packs that best suit the application. The mobile phone industry is a good example of this clever adaptation. Here, small size and high energy density reign in favor of longevity. Short service life is not an issue because a device is often replaced before the battery is worn out. Below is a summary of the strength and limitations of today's popular battery systems. Although energy density is paramount, other important attributes are service life, load characteristics, maintenance requirements, self-discharge costs and safety. Nickel-cadmium is the first rechargeable battery in small format and forms a standard against which other chemistries are commonly compared. The trend is towards lithium-based systems. Nickel-cadmium - mature but has moderate energy density. Nickel-cadmium is used where long life, high discharge rate and extended temperature range is important. Main applications are two-way radios, biomedical equipment and power tools. Nickel-cadmium contains toxic metals. Nickel-metal-hydride - has a higher energy density compared to nickel-cadmium at the expense of reduced cycle life. There are no toxic metals. Applications include mobile phones and laptop computers. NiMH is viewed as steppingstone to lithium-based systems. Lead-acid - most economical for larger power applications where weight is of little concern. Lead-acid is the preferred choice for hospital equipment, wheelchairs, emergency lighting and UPS systems. Lead acid is inexpensive and rugged. It serves a unique niche that would be hard to replace with other systems. Lithium-ion - fastest growing battery system; offers high-energy density and low weight. Protection circuit are needed to limit voltage and current for safety reasons. Applications include notebook computers and cell phones. High current versions are available for power tools and medical devices.

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