digital batteries

Introduction

In recent years, the popularity of the car, NOx, COx increased displacement, environmental pollution and problems of global warming worse. To this end, many countries are actively implementing the hybrid electric vehicles and electric vehicles to replace conventional cars. But more importantly, these new energy vehicles require high energy density, high voltage, rapid charge-discharge characteristics of energy storage media in support, such as lithium-ion batteries. Battery charge and discharge as a practical device to fully play its role, its large capacity, high accuracy, reliability has been increased. To effectively play the battery performance, this article will serve as high capacity batteries for the design of electrical systems. hp Pavilion DV1000 battery hp Pavilion dv6 battery

System Components 1

(1) Overview

Battery charge and discharge device circuits are mainly two. A kind of the linear amplifier (Charger) + load impedance (electric shock), etc., hereinafter referred to as composition 1, while the two others by the system for the converter + inverter (electrical charge and discharge) with the following form short 2 first to compare the advantages of both.

The battery charger is now on the market is about half of all 1, because the charger phenomenon consisting of fever, and large, use the launch site restrictions. In the words of the electrical work, if you want two-way transmission of energy, is then a 2 is the best.

Here for form 2, on two different ways to discuss the design of circuits.

The process of designing the system first type voltage inverter combined buck-boost converter and two-way combination of a battery charge and discharge device, ahead of the second draft is adopted high supply load capacity and electronic equipment (hereinafter referred APL2). For APL2 can turn any battery voltage, current, such as food or load may be a 0kW input and output (making the voltage 0 ~ 200V or 400V). 417066-001 hp pavilion dv6000 battery

The first step of design, the system and the isolation between the power transformers, the reactor section Buck converter, the switching unit so small, the existence of certain problems. Meanwhile, the subsidiary of the high frequency transformer isolation circuit, the inhibition of cells pulsed current buck converter, and the reactor is essential.

The approach of the second project, namely, the use of APL2, does not change depending on the battery to change the nameplate capacity of the circuit. At the same time, increased through the series circuit and the charge and discharge current characteristics of small and light.

As the design of a case, the nominal capacity of 1 0kVA the same design conditions, the design results of this comparison is the second volume of the approach to device design is the first design approach 1 / 2. Based on the above analysis and comparison, this implies the use of APL2 and the battery discharge device. hp 520 battery hp 530 battery

(2) The base composition

The system settings simply by a fiber optic cable can be connected and APL2 user’s computer. Meanwhile, the use of this system can be achieved within the Windows system, the development of battery charging and discharging system

(3) Control scheme

Figure 2 APL2 constant current modes when the control block diagram. Enforcement costs and waste, downloaded from a computer model data that the value of outstanding orders, for the constant current control. While charging, the battery voltage reaches the predetermined maximum voltage value, automatically switches to constant voltage mode control and load slow.

Shown in Figure 2, the charging circuit and discharge instruction loop to switch contacts, but is actually using the DSP to pass the program, almost no switching delay. APL2 as a battery charge and discharge device, without changing the internal structure, it can be applied directly to control the characteristics of the circuit. apple macbook pro 15 inch battery apple macbook pro 17 inch battery

2 Application Example

The capability of an application APL2 large, high-voltage ion battery charge and discharge system. battery charge and discharge unit as an object, the maximum voltage of 336V, load and discharge current of 00A ± 1. Figure 3, the composition of the system, Table 1, the basic specifications for the APL2.

Rated voltage of the current system for 400V/25A APL2, to increase capacity by using the master-slave, the maximum can be parallel four APL2, can load and unload under 100A. Figure 4 shows the 0 ~ 90 load voltage and current waveforms of the elbow, recharging the battery type switching power stage has been the response waveform, Figure 5 shows the 0 waveform ~-90A of current when the battery voltage discharge of the battery, when the current changes have been the step response waveform. The current from the battery, first specify the output current APL2 home, while the slave is responsible for monitoring the host and release current value and change orders. apple ibook g4 14-inch battery apple macbook 13 inch battery

The system 1 00A may be performed quickly on the charge current S-velocity and discharge control can be used to charge the lithium-ion battery and discharge characteristics of the basic test.

3 Conclusion

According to this design method can be used directly for APL2 load capacity of the battery and draining device, the embodiment of the system small and lightweight, the corresponding reduced system development between Japanese inches. In this paper, we introduce the charge lithium ion APL2 and discharge system of the situation, it can also be used for loading double-layer capacitors and rejection, EV and HEV Motor · ninth power system dynamics and other areas, and space-saving and energy saving features. apple a1189 apple ibook g4 12-inch battery

● Design of shielding and signal ground

In the fuel cell electric vehicles, high power DC / DC converters and other control circuits, motor controllers and other equipment placed together between Yao radiated electromagnetic energy, usually associated with the shield and shell mode gap shield for protection against radiation suppress interference. In addition, the mass signal eliminates the outside world or other equipment with high VEGF power DC / DC interference, the key is to choose an appropriate reference point for the circuit and line grounded in sound public distribution. Dell Inspiron 1525 battery Dell Vostro 1520 battery

High Power DC / DC converter control circuit anti-jamming design

Control circuitry is the high power DC / DC are an important component of good design advice can significantly improve the immunity of the circuit.

High Power DC / DC converter control circuit mainly by the power supply, the sampling of signals, communication signals and the driver modules, to avoid interference between signals in the circuit design at its isolation, as shown.

VEGF in high power DC / DC converter control circuit, the power module is commonly used in isolated DC / DC module, realized the power of entry and exit of electrical insulation. isolation of the sampling signal, including the isolation and the isolation voltage of sample collection. Communication signals using optical couplers HCPL0600 isolation to reach the entrance of the CAN bus and output signals of the optical isolation. VEGF with DC / DC converter output is bigger, so that using IGBT power switch and IGBT drivers with different specifications for different methods of isolation. General IGBT driver with low power isolation TLP250, medium-power IGBT drive for a more EXB841/840 Series modules driver isolation, high power IGBT modules or ultra-high power may be used to achieve the 2SD315A drive isolation. Practice shows that the isolation of each functional module, the control circuit can be greatly reduced interference between the different modules to ensure the reliability of signal transmission and signal processing precision. Dell Latitude D610 battery Dell Inspiron E1405 battery

High Power DC / DC converter design software interference

High Power DC / DC converters are usually controlled by DSP, the anti-jamming design software is also very important. High Power DC / DC conversion software interference of two main aspects to consider: DSP technology for filtering interference immunity and Software Technology, the first is mainly due to the interference against the procedure because “run off”, which is primarily to eliminate the signal interference to improve system accuracy.

DSP technology, anti-jamming

VEGF in high power DC / DC converter operation, once the interference DSP control system will have very serious consequences, even make the system of fuel cell electric vehicles paralyzed, so when designing the real system, are considered as interference occurs, the DSP system against its own measures. Dell Vostro 1220 battery Dell Vostro 1220n battery

To improve the immunity of DSP, the new DSP controller (as TMS320LF2407A) module integrates a watchdog timer (WDT), used to run the monitoring program is a combination of hardware and software procedures for managing anti Fly-measures. WDT is used to generate the material of the main cons or timer trigger monostable T, the counter or trigger basic single autonomous and stable, termination synchronization output line reset the DSP and time allowed by the DSP control software.

Under normal circumstances, the program began after the WDT, and in some time, the time T reset to clear, so the timing WDT overflow will not occur because no effect of sleep normally. Interference of Yichang in the context of the situation, the destruction of temporal logic processor implementation of the program, chaos, Bu Keneng WDT cleared periodically, Zhe Yang a time when the WDT overflows, the output reset Shi Ji Tong DSP processor Baituo Yin Er in a temporary disruption paralysis. dell inspiron 2600 battery dell inspiron 2650 battery

Antispyware

In this article, a filtering technology VEGF high processing power DC / DC sampling data. High Power DC / DC converter will be collected using the analog controller filtered sent to DSP A / D converter channel, launched by the software programming / D conversion, to obtain the value of the sample A / D integrated in the register in.

DSP signal interference Duocheng around the shape of burrs, a relatively short duration of action. Sampling of the analog DSP, it can be repeated on the same analog A / D conversion, and several times the value of temporary storage in the sampling area of internal data. After repeated sampling when using data filtering algorithm and multiple methods of sampling the average value of data processing software that can improve the fight against-interference, improve data accuracy and sampling accuracy. dell inspiron 1520 battery dell inspiron 1521 battery

Conclusion

In this paper, high power DC / DC converter and the main sources of interference suppression measures to control the electromagnetic signal circuit isolation and design software to interference VEGF high power DC / DC compatibility electromagnetic study and an effective solution to the VEGF high power DC / DC EMI. With EMC Design VEGF high power DC / DC converter has been applied successfully developed by Tsinghua University, the fuel cell buses, technical indicators are used to meet the vehicle requirements, works well. dell inspiron 1720 battery dell inspiron 1721 battery

Introduction

Currently, electric vehicles to fuel cell (FCEV) become the main direction of technological innovation of the automobile. System for Fuel Cell Electric Vehicle Power consists of an engine fuel cell, DC / DC converters, battery, motor controller (inverter) and the DC motor, system acquisition CAN bus data and composition of Figure 1. Including DC / DC converter controls the production of fuel cells and energy transmission and conversion, fuel cell electric vehicle key components. In the fuel cell electric vehicles for the course, DC / DC converter in which the electromagnetic environment is very complex and many forms of electromagnetic interference, has seriously affected the normal operation of the DC / DC converter. Therefore, the study with DC DC Converter VEGF electromagnetic compatibility DC / DC and battery electric vehicles to fuel and reliable operation is important. Dell Inspiron 1721 battery Dell Inspiron E1505 battery

High Power DC / DC converter main source of interference and electromagnetic compatibility design

VEGF with DC / DC converter is a device for power conversion, electromagnetic compatibility electromagnetic environment in VEGF has a significant impact. VEGF with DC / DC working on the world a strong electromagnetic interference, not only interfere with the VEGF, but also affects the DC / DC converter control system of their own work. Therefore, VEGF to improve system performance must VEGF with DC / DC The search for electromagnetic compatibility, electromagnetic interference generated by its (EMI) effectively inhibited. Dell Latitude D830 battery Dell Inspiron 1150 battery

High Power DC / DC converter main source of interference

VEGF with DC / DC power converter is generally larger, often choose as IGBT power switches. IGBT power switches work produced during the high dv / dt and di / dt and the increase of peak current and voltage, which is VEGF high power DC / DC converters to generate the most fundamental causes of electromagnetic interference . In addition, the power switch on and off instantly, as inductance and distributed capacity of the existence of the inductor is a high frequency oscillation, these factors have a strong electromagnetic interference, which VEGF high power DC / DC converter performance particularly sensitive. This electromagnetic interference severely affected vehicle controller and CAN communication, communication can often lead to error, not the normal communication. CAN communication interference waveform is displayed after the transfer. From the figure, it is clear that the converter switching noise superimposed on the pulse on the CAN communication and the increase was significant. In addition, EMI will also make a serious high-power DC / DC output ripple of the converter is too large, the ripple is too large direct impact on high power DC / DC converter performance. Dell Vostro 1500 battery Dell XPS M140 battery

High Power DC / DC measures electromagnetic interference suppression

Currently, inhibition of the high power DC / DC EMI measures reduce the main sources of interference intensity of electromagnetic interference, electromagnetic interference cut the transmission, distribution and rational use of sensitive components and the shield design signal ground.

● reduce the intensity of the interference of electromagnetic interference

High Power DC / DC converters generate electromagnetic interference is mainly due to the rapid changes in voltage and current, and thus need to minimize the voltage and current exchange rates (du / dt and di / dt) . The most common method is to increase the absorption circuit, the circuit can inhibit the absorption of electromagnetic interference, the basic principle is that when the switch is turned off to provide diversion, savings in the parasitic absorption parameters of energy distribution, thus preventing the appearance of interference. More technology soft switching converter is the focal point of research in recent years [4], VEGF high power DC / DC converter using passive soft-switching resonant flexible technology can significantly reduce the process of switching / dt and di / dt, not only to reduce switching losses, but also significantly reduces electromagnetic interference. In addition, by optimizing the power switch control IGBT, selecting the power button IGBT drive voltage and gate resistance, may also reduce interference from high power DC / DC EMI. Dell Vostro 1710 battery Dell Latitude D810 battery

● cut channels of electromagnetic

VEGF high power DC / DC electromagnetic interference generated mainly by conduction disorders. The most common method is DC / DC converter input and output filter capacitor installed. To reduce VEGF high power DC / DC on the CAN communication interference, in converter input and output plus an appropriate amount of capacitors grounded, effective communication can improve the waveform.

VEGF in high power DC / DC converter, the output voltage or current ripple is an important indicator of food. Figure 4 in the high power DC / DC converter to connect the CLC filter output, the converter output voltage waveform smooth, reduced switching noise, filtering is obvious. dell inspiron 6400 battery dell inspiron 640m battery

In addition, VEGF high power DC / DC converter switch to a dozen kHz frequency IGBT turn on and off the circuit can have a high incidence of harmonic current output voltage fuel cell. Therefore, DC / DC converter input and output are generally parallel capacitor (electrolytic capacitors without any sense of capacitors in parallel). No sense capacitor filter circuit can occur because of interference radiation frequency resonance, while the electrolytic capacitor to stabilize the output voltage of fuel cells and reduce the intensity of the radiation, and reduces the DC / DC output voltage ripple.

● rational distribution of sensitive components dell inspiron 6000 battery dell inspiron 630m battery

VEGF high power DC / DC converter contains many sensitive components (such as Hall sensors in progress), these sensitive components are very sensitive to electromagnetic interference. VEGF in high power DC / DC Converter for switching on actual layout of components usually sensitive to the power switch in the IGBTs, freewheeling diode and a transformer at high frequency, the farther Xian stranded signals and reduce the wiring distance This can significantly reduce the current noise signal, improve the control performance. Meanwhile, VEGF high power DC / DC converter wiring connection, we should try to be sensitive to the signal line of IGBT power switch, diode and high-frequency transformers and other strong sources of interference. At the same time, not with a high voltage AC signal and high frequency pulse signal is put together, should ensure the proper distance. dell inspiron 5150 battery dell inspiron 5160 battery

USB Power Manager – LTC4085

LTC4085 is a portable USB power manager self monolithic ideal diode controller and standalone linear battery charger. LTC4085 PowerPath control with, or the USB VBUS power adapter AC to power the system load, and single-cell lithium ion / polymer battery charger. To comply with USB specifications to the limit, LTC4085 automatically when the system load current increases, thus reducing the battery charge current. To ensure that the battery is fully charged when the bus connection is not used as such, the IC by the USB bus to power the load Shusong, but have no power to the battery practice. Once the power is off, the current through a 200mΩ ideal diode low loss rate of the battery to the load, thus reducing the voltage drop and power dissipation. Provided advice to drive an optional external PFET GATE circuit for connecting peripherals to the case in the application necessary for the overall ideal diode impedance below 30mΩ the following. LTN141W3 LTN141X7 LTN141X8

LTC4085 unique feature is the AC adapter can detect the access and use it as a kind of power system load while charging the battery backup power. LTC4085 also provides access to an AC adapter in the case of higher values to USB specifications allow (100/500mA) rating (up to 1.5 A) to charge the battery option, so they can dramatically increased rates of charges the battery. The total cost of time late charge by an external resistor to set. When the load current decreases, the load timer period will be automatically extended to ensure that the battery is always fully charged state. Additional features include automatic recharge, NTC thermistor input, input adapter is automatically removed the battery, limiting the inrush current, reverse current blocking, lock-out under-voltage and thermal setting.

LTC4085 float voltage is preset at 4.2V from 0 to 85 ℃ temperature to ensure the accuracy of 0.8%. Charging current can be easily adjusted using a resistor. The optimum temperature for charging the battery of pre-treatment and certification will automatically be set to 10% of the total flow of the trickle charge current battery until the battery voltage exceeds 2.8V up at. LTN141XA LTN141XB LTN141XC

For, like GPS navigation devices, PDAs, digital cameras, digital photo player, MP3/MP4 players and other handheld devices, offering the USB port and the input voltage, high load capacity and battery has many advantages such as energy USB if you have not driven on the road to bring the convenience of the charger, a laptop from a PC or other device with USB port to power your device. Such as FireWire, 12 ~ 24V AC adapter or car adapter, car power can input-output high voltage to provide a higher speed of USB charging, and allow more places (like cars), taxation , which is to improve facilities One of the keys to portability.

Convenience features and high power

LTC408 And LTC408 -5 Is a portable USB power manager self, ideal diode controller and standalone high-voltage battery charger for high efficiency. To achieve efficient load their switching topology can be adapted to a variety of appetizers, including up to 36V (40V max) of high voltage (like 12V AC adapter, car adapter and a FireWire port). In addition, they also accepted such as adapters and USB 5V supply low voltage. LTC408? -5 With PowerPath control feature, available on the USB or power adapter to the equipment and materials of the lithium-ion battery charging, but also the introduction of a severe shortage of battery power is exhausted or the situation to achieve “instant-on” operation. LTN154X1 LTN154X2 LTN154X3

To comply with USB specifications to the limit, LTC408? -5 Load current increases in the system automatically reduces battery charge current when. To ensure that a fully charged battery is connected to a full charge state when the bus termination, the IC by the USB bus to transport power to the load, but did not take lessons from battery approach. Once all food was removed, then the current through a 200mΩ ideal diode low loss rate of the battery to the load, thus reducing the voltage drop and power dissipation. Provided to drive an optional external PFET circuit board to the case in the application necessary for the overall ideal diode impedance below 30mΩ the following, which will enhance the work efficiency.

When LTC408? -5 Power from USB port to provide power management system allows the maximum available power, which increased by 2.5 W (500 mA x 5V) from the USB power solution available. In addition, it would, the system automatically adjust the load current lithium-ion / polymer battery charge current to maintain the total input current limit consistent with the USB. LTN154X7 LTN154XA LTN156AT01

LTC408 Switching regulator with output track the BAT-based adaptive control, which greatly improved its offer 1.2A charge current from the battery charger efficiency, because the output voltage of the switching regulator automatically tracks the voltage of the battery. LTC408 -5 from the input voltage high is a fixed 5V output, used in single-cell lithium-ion / polymer battery charger. The float voltage battery charger is preset to 4.2V, at intervals of 0 ~ 85 ℃ temperature to ensure the accuracy of 1.0%. Charging current can be easily adjusted through a resistor. The total cost of time late charge set by an external capacitor, and provides an output charge detection C/10 current. Additional features include automatic adjustment for temperature qualified charging heat to the NTC thermistor input, the battery will automatically recharge, reverse blocking and lock-out being energized. LTC408 -5 With flat (height of only 0.75 mm) 6mm 22-pin 3mm × tiny DFN package, and the guarantee of -40 ~ 85 ℃ operating temperature. dell gw240 dell rn873 dell y6142

BAT-track control output adjustment

LTC408 AT-Track function adaptive output control is a form. This is a battery charger and switching regulator integrated, so that the switching regulator does not produce enough to sustain the required voltage of the battery charger, but does not produce additional tension. Linearly supply for the product, the input voltage and voltage difference of the battery in the charging process is lost as waste heat.

Where implementation of a switching regulator, the switch to both ends of the pressure drop as large as possible is beneficial because it can effectively accomplish the (absorbed by the input current is less than the current supplied to the charger). dell gk479 dell nf343 dell pc764

BAT-Track function is responsible for detecting the voltage of BAT, and switching regulator output VOUT to adjust to the battery voltage VBAT exceeds 300mV, minimizing power loss caused by heat, can charge the battery properly and maximize reduce total electricity consumption. This greatly improves the efficiency of the battery charger. For example: When the load current IBAT = 600mA, VBAT = 3.7 V input voltage VIN = 5V charger, the charger efficiency (with the substitution method element) is as follows: 100 × POUT / (POUT + PDIS) = 100 × (× VBAT IBAT) / (× VBAT IBAT PDIS +) = 100 × (× VBAT IBAT) / (VIN x IIN) = (3.7 × 600mA) / (5V × 600mA) = 74%.

Conversely, if the charger voltage VBAT input exceeds 300mV the charger efficiency: 100 × (× VBAT IBAT) / (VIN x IIN) = (3.7 × 600mA) / ((3.7 V 0.3 V) × 600 mA) = 92.5%.

This difference in efficiency will significantly reduce energy consumption. In addition, if the battery against discharge and voltage VBAT to low, the minimum should be 3.6V VOUT, to ensure that the system load for a sufficient supply voltage. dell hd438 dell y9943 dell fk890

Devices, small portable consumer batteries, cheaper, and accepting a variety of input power to achieve the usability requirements engineers to design the system to bring many challenges. Using PowerPath series battery management can effectively address these challenges, is an independent operating characteristics can be independently a wide range of supply (cigarette lighter adapter Ru FireWire input, AC USB, and the battery itself) between Qiehuan transparent implementation of effective management. LP154WE2 LP154WX2 LP154WX3

Handheld battery today engineers design equipment, they are the major challenges facing Suo Yi Xie minimize energy consumption and minimize Tigaoxiaoshuai, simplify design and reduce Chengben.

Many battery-powered portable electronics available today from the AC adapter, car adapter, USB port, or lithium ion / polymer. However, these sequences between different power supply control of self-management has great technical challenge. Throughout, the designers are trying to adopt a “discreet” way to accomplish this function, which uses a large number of MOSFETs, op amps and other discrete components, but during the meeting are likely to cause major system problems, and the influx of hot-plug and other current issues. Recently, even discrete IC solution also needs to use multiple chips to achieve a practical and integrated power management ICs can easily solve these problems. In addition, CI own independent operation also removes an additional termination for the realization of the need for an external microprocessor, thus further simplifying the design. LP154WX4 LP171W01 LP171WP3

When used, such as FireWire, is not regulated high voltage (> 5.5) AC adapter and cigarette lighter adapter, the adapter voltage source and portable devices, the voltage difference between batteries large. Therefore, the linear charger may not be able to solve the problem of high energy consumption, while the use of topology switching IC is able to improve efficiency and reduce thermal management problems. Note that when using USB, Lithium ion polymer battery or adapter input less than 5.5V to power the linear charger device power management is a more appropriate choice.

PowerPath control

With control device from PowerPath USB VBUS power adapter for his own power, and its lithium-ion rechargeable single cell. To ensure that the battery is fully charged when the connection is not used in the state of the bus, the IC directly through the USB bus power the load, rather than receiving power from the battery. Once removed from office, the current through an internal low loss ideal diode current from the battery to the load, thus reducing the voltage drop and power dissipation. LP171WP5 LP171WP6 LP171WX2

Features PowerPath control:

1. Food USB access adapter or battery;

2. In the OUT pin is connected to a circuit application and a battery connected to the power transmission BAT pin (assuming that access to external power, battery);

3. Does the battery charge current is regulated to ensure that the load current and load current and no more to define the boundary USB input current;

4. AC adapter current through an external device (such as power Schottky diodes or FET) connected to the output (load side);

5. With a unique feature, you can use the AC adapter to power the output power to the load while charging the battery;

6. Output pin of the load may be a priority in the current USB input. LT141X7 LT150X3 LTN141W1

Ideal diode

When the output / load current exceeds the input current or voltage input is removed, the ideal diode low loss battery to provide power. The ideal diode (not to load directly connected to the battery) to give the load a fully charged battery can power an external power to maintain full charge before the state abolished. Once the external power source is removed, the output voltage drops until the ideal diode forward bias is applied so far. Canada has the ideal diode voltage before the battery then provides an output to the load. Ideal diode voltage drop much lower than conventional diodes, and reverse leakage current of less. Small forward voltage drop to reduce energy consumption and self-heating, which prolongs the life of the battery.

Ideal diode has the following characteristics:

1. When the output / load current exceeds the input current, or when the input voltage is removed, the ideal diode components for supplying power from the battery; Dell Vostro A860 battery Dell Vostro A860n battery

2. The ideal diode (not to load directly connected to the battery) to give a full load power supply can recharge the battery in the external power source is removed to maintain full charge state Zhi Qian, and makes the unit even in a fully depleted by the battery cases to function properly;

3. Once the external power source is removed, the output voltage drops until the ideal diode forward bias is applied so far. It also has an ideal diode voltage before the battery then provides an output to the load;

4. If the battery is the only power source available or load current exceeds the input current has been set, then the battery will be filed by a bat and pins on the ideal diode circuit between the power transmission automatic load; Dell Vostro 1720 battery Dell Vostro A840 battery

5. Ideal diode (as well as recommended capacitors on pin OUT) allows IC to the body without using large capacitors in the treatment of high dynamic loads and the AC adapter or USB VBUS connection disconnection model /;

6. Ideal diode low loss path to power by reducing the IR drop extended run time battery.

Linear Technology Power Management IC Series for solving design problems above. In the field realize the function of two important new products LTC4085 USB power manager and high-voltage battery charger LTC408 Source Manager. Dell Vostro 1510 battery Dell Vostro 1710 battery