24/11/2011

Lithium-ion battery and battery charger reference design

Presentation


The portable electronic work with the battery. With the rapid development of mobile products, has increased the amount of the battery, and a lot of new batteries. In addition, we are more familiar with the alkaline batteries, rechargeable nickel-cadmium, nickel metal hydride, not in recent years of large lithium-ion. This will introduce lithium-ion, including knowledge of the properties, the key parameters, applications and provide the last line of lithium-ion Dell Inspiron 1200 Battery design reference.


Development and application of lithium batteries


Lithium batteries are currently the most common battery is new, in accordance with the requirements of various electronic products in a flat, rectangular, are cylindrical, rectangular converted, and a button that you can insert a low-power applications can use also multistage series-parallel combination to be a higher voltage and capacity of HP elitebook 2530p Battery power tools and laptop computers. Lithium-ion can be a gel electrolyte, the polymer (Li-Ion / Li-polymer), or a mixture of polymer gels. Why not at room temperature, the actual supply lithium-ion polymer is, most lithium ion / polymer battery is actually a combination of gel-polymer hybrid battery.


Lithium batteries are different from chemical batteries, loading and unloading of his work through the process of integrating the positive and negative electrodes of lithium-ion battery and scope, while recharging the battery, the cathode generation Lithium-ion generation lithium ion moves to the cathode through the electrolyte. Since the carbon anode was layered structure, has many pores, reaching negative electrode of lithium-ion layer of porous carbon, integrated lithium-ion, more resilience built. Similarly, if the battery Dell Inspiron Mini 1012 Batteryis low, the carbon layer embedded in the cathode of lithium-ion extrusion, and again at the cathode. Back to the cathode of the discharge capacity lithium-ion is higher. In general, we refer to the battery capacity refers to the drainage capacity. The charge-discharge process, lithium ions in the cathode to the anode to the cathode, the cycle of movement. Since the lithium-ion batteryDell Vostro 1310 Battery lithium-ion state rather than lithium metal, with a low risk, high security use.


Characteristics of the battery


Performance parameters of the battery are the strength, skill, energy and power. Electromotive force equal to the unit positive charge from the anode to the cathode of the battery, the battery is not static (chemical forces) at work. Electromotive force depends on the chemical nature of electrode materials, and size of the battery. This is the total output of the battery, the battery capacity, usually in ampere-hours.


The response of the cell containing the substance per kg of product with the current theoretical specific energy of the battery. Refers to the energy per unit weight or unit volume specific energy stored Wh / kg or Wh / L to represent. WH is a unit of energy, WW, h is the hour in kg (weight), L is the liter (volume). The real power of the Dell Vostro 1500 Battery, the theoretical specific energy than small ones. Because the battery is not all reagents in the reaction after the battery while the battery internal resistance causes a voltage drop. On the other hand, the current through the battery reduces the cross-section through the resistance. Lithium-ion is the highlight of today's high-tech lithium-ion energy can reach over 80 kg ~ 120 Wh /, while the traditional lead-acid battery is only 30 ~ 40 Wh / kg, and lithium - ion battery can store energy in a small format, can only bring out the light for mobile computing devices and applications demanding the life of the electric vehicle.


The following list contains some properties of lithium-ion battery: High capacity Li-Ion is the same weight capacity of nickel-cadmium or nickel metal hydride, half the volume is 20-30% of the nickel-cadmium, nickel-hydrogen from 35 to 50%.


● high-voltage lithium-ion battery voltage of 3.7 V (nominal), the equivalent of three sets of nickel-cadmium or nickel metal hydride batteries.


● High stability: Due to non-lithium, low-risk, and therefore beyond the reach of the operators of aircraft to the limit to implement the plan.


● Long life lithium-ion batteries battery dell vostro 1500 are fully charged, the voltage drop of about 4.2 volts, the discharge voltage is stored, but not less than about 2.5 volts, the voltage of the voltage plant, about 3 to 6 to 3.7 volts. The key number for the life of the burden of a life long lithium-ion battery of approximately 500 times (from 2.5 volts to 4.2 volts charged only counted once), and the memory effect of lithium -ion ​​battery is not present.


● Quick charge a nominal voltage of 4.2 V DC voltage / constant current charger can be lithium-ion-1 to 2.5 hours at full load. Note, if the charging voltage of 4.3 volts or more, there is the danger of an explosion. The battery voltage drops below 2.0 volts, the loss of lithium-ion battery, can not use or being charged.


Charging the battery


Can "to solve the load IC," say the above, although requiring lithium batteries Vostro 2510 Battery with high power and benefits of long life, but the loading and unloading aspects of attention to all the lithium- ion recharge and discharge set the border to ensure that the battery voltage through the security of explosion if the battery voltage to avoid causing reduced production below 2.5 V on the life the battery. In addition a number of standards, sees most of the lithium battery of different sizes for the practical application of basic properties are not the same, so the current project is supported by some manufacturers. Depending on the size of the loading mode charging current so-called fast or slow, you can download the current mode is generally harmful to life. Even if the battery contained in a charging circuit for the integrated management, but only to avoid the explosion of the battery or the minimum measures to protect against burns, rather than normal use, to fully realize the Inspiron 2650 Battery and the efficiency ", the rest of this sophisticated design and Chargers lower limits as well.


In addition to the excessive discharge, lithium batteries are not suitable for high pressure discharge lamps, high relief reduces the discharge time (internal temperature will produce a greater loss of energy). Therefore, the maximum battery manufacturer's specific products currently in use less than the maximum discharge current. Lithium-ion for the needs of high quality require sophisticated Inspiron 1525 Battery charging circuit for the security, in particular, to stop the charge voltage accuracy of 1% of the nominal value (eg 4.2 V lithium ion tolerance of ± 0.042V) below circuit voltage lithium-ion battery can cause permanent damage, severe cases leading to the explosion of the battery, lithium-ion battery as specified by the manufacturer of the battery . Although some of the rated load current of the battery 2C (C is the battery capacity 1000mAh, 1C charge when the charge current is 1A is checked), but the load reduces the battery life at high currents, so that the density of ~ 0.25c 1C general use. To produce by the head of the electrochemical reaction to heat, the energy loss to other lithium batteries are not all consistent with the load in constant voltage mode here, so real-time charge of approximately 2 , 5 hours, lithium ion temperature between 0 ~ 60 . Excessive load current is generated when the temperature is too high, not only cause damage to the battery and an explosion. Therefore, the current capacity, detecting the temperature of the Inspiron 1545 Battery, and if the temperature along a levy on the task of adopting security. In addition to the load circuit, the current limiting resistor to ensure that the load current is not the limit of the current intersection.


Lithium-ion battery is often three-step method of collection, pre-load (pre-charge mode), a (fast charge mode) at constant current, constant voltage (constant voltage mode) are used. Discontinuation of lithium-ion battery discharge voltage of 2.5. May well designed battery chargers to determine the battery power that pre-treatment before the formal charges to spare. Supported by the demonstration of the battery if the battery voltage greater than 3V as a function of normal load and the battery Inspiron 1720 Battery voltage drops below 3V, the scene of a low current (about 10% of the load current, in constant current mode) is called the burden of pre-charge mode, so the depth of discharge in a state of dissolution of the passive film restored. In addition to causing excessive discharge when the battery can cause, and a whole bunch "of copper anode in a short-circuit currents in excess of strength in this time, the overheating of the Inspiron 1521 Battery, but pre-loaded at this stage to avoid. 3V or other expenses, while the normal mode, the load voltage constant.


If the battery voltage greater than 3V, depending on the load characteristics of the normal load of Figure 1 (a 4.2 V lithium-ion battery, for example). He began to load in constant current mode, the battery voltage to rise to a faster increase of the slope, with the increase of the battery, the Vostro 1500 Battery gradually decreases the slope of the voltage rise to about 4 , 2 V, constant current is over. Change a constant voltage charger is 4.2 V, constant voltage phase of charging voltage is almost constant, but the decrease of the load current. If the load current to a value to activate the timer, the timer is a period after the loading process succeeds.


Constant charging voltage accuracy of the Inspiron 6000 Battery output voltage with a maximum capacity of the battery and autonomy are important. If the battery voltage falls below 4.2V, the charger can cause a breakdown, if not, your life, but it makes the battery capacity is reduced. For example, as the state of charge is less than 1% of the total voltage of the battery capacity is reduced to 8%. On the other hand, the battery voltage is too high, reduce congestion and battery life, or even that the user is in danger. To ensure the safety of lithium-ion battery allows you to charge the battery when the ambient temperature between 0 ~ 45 . Charged at a lower temperature, lithium, the impedance of the battery and the deterioration of the battery. In a high temperature environment for charging, the electrolyte increases the reaction with lithium and accelerated deterioration.


Generally, we recommend that long ago, if not used, put the battery from 70 to 80% for storage should be kept. It is a long period of natural drainage of the battery voltage to prevent the sub-ion 2.0 volts, which can not be a failure of the lithium ions are used. Often short of lithium batteries with loading and unloading is often used, life expectancy reduced by about half.


Lithium-ion battery is designed to taste


To answer these products at low power chargers for portable applications more accurate and safer, many chip manufacturers to develop low-cost linear charger. 2 is loaded by Kerry Technology LD6275 example circuit design, some parts of the linear circuit of the load independently, the maximum current of 1.5 A is.


LD6275 is integrated linear Li-Ion battery charger integrated circuits, route of administration is active, the load currents in the case of loading / unloading, the adjustment in the Inspiron 6400 Battery life in real-time monitoring input and ongoing management (eg, power output USB port), in accordance with USB - If the call default limit current and soft start function. In addition, a high-temperature measurement IC when the temperature exceeds the set value IC. Automatically reduces the charging current to the chip damage.


Avoid LD6275 AC adapter / USB 5V DC step-down constant current lithium-ion battery, AC adapter for protection against overcurrent due to overload, you can set the maximum current strength RCISET external load. USB also supports the loading, and are determined on the basis of external pins EN1 and EN2, see Table 1 for each mode. The USB 500mA mode 100mA in USB mode, you can protect the USB port on the PC side, to prevent overloading.


MAh under the assumption of a single supply voltage of 5.5 V Li-Ion 1200, 0.7 under the conditions of Dell Latitude D820 Battery voltage and 3V raging current, an estimate of the maximum operating temperature IC This 1.762W max power is the thermal resistance at 60 / W, 3 x 3 mm QFN Temperature 127 temperature, even when the ambient temperature of 0 , 125 exceed silicon chip, the maximum temperature. When the load current of 0.6 A (0.5 C), the chip temperature of 90 degrees, and at room temperature of 35 degrees is much better to operate together now.


Can learn from him, faster than the carrying value of the operation voltage constant current and constant, it is important for a linear charger. The fundamental problem is a linear charger when the temperature of the chip is higher, so the design must compromise between the load current and the heat sink. But often, the application of the linear charger for portable products is slightly higher than the use of low thermal conductivity of the plastic should not believe no heat sink metal design of the final product and reduce the load current increases the load at a lower temperature of operation. Users of portable products in the hope that in 1 or 2 hours after completion of the loading process, so that a linear charger is usually best suited for applications such as low capacity 1500mAh lithium-ion battery. Apply to the high XPS M1730 Battery input / output voltage difference and applications of high performance battery, you should consider using the charger synchronous switching regulator.


Figure 6 shows the battery charger lithium ion, standard load, the load of the first integrated circuit short-circuit output and the type of protection against overloads detects if everything is normal, the system detects that the battery 3V 3V or more of the first fast charge mode directly to the ICU, when the Studio XPS 16 Battery drops below 3V to enter into an agreement for the pre-load and 10% of fast charge, the battery alarm to avoid damage the battery. Cut saw in the pre-load and the battery voltage at any time in the 3V immediately after the fast charge mode.


n, the fast charge mode, the battery voltage to a growth rate of 4.2 V, then reduce to a constant charging voltage of 4.2 V, the internal resistance of the battery current to Bunsen, when the load current as shown in Figure Stadium the first CV. Over time, the load current decreases exponentially when the current rate ICHG 10%, or down by the shipper at the same time as loading is completed.


However, if the BatteryDell Inspiron 1300 is discharged, can not store the battery in positions of power, the current does not increase depression, full of energy as heat, high temperature protection, and more time in Apart from several trusts, CI had internal timer of death, or when the battery voltage at the office time to adjust, then turn the charger to a security feature of multi-user access.


The user can load when the load is not without the power of what was to complete a battery. To avoid the risk of IC must be submitted in 7, 8 batteries detection methods. IC, a short pulse (2 ms pulse is generated every 370m) to take the battery if the battery is present, then the battery voltage must be detected above a predetermined threshold and if the battery will be responsible for IC detects a low voltage battery and unplug the Battery For Dell Latitude E6510power for the safety of our users to be determined.


Lithium-ion batteries for its unique performance advantages in portable devices such as laptops, cameras, mobile communication is widely used. The new generation of lithium-polymer battery that can be done in the form of fines, and a region of arbitrary shape, greater flexibility in the design of the battery. Meanwhile,  lithium-ion polymer Dell Inspiron 9300 Battery increases energy than current lithium batteries usually about 20% capacity, and other aspects of performance lithium-ion environment can be improved. It is expected that the future of battery Lithium-ion faster, more robust protection for future development trends.