A laptop charger provides power to the laptop and the battery. Without a correctly functioning charger, the computer will not hold a charge. In some cases it is possible to take the laptop charger apart and make any necessary repairs. Often, the cord on the charger has shorted out and must be fixed. The process of taking apart the charger is straightforward, although the outcome depends on how the charger was built and secured by the manufacturer.
1.Open the laptop charger by inserting a flath
ead screwdriver into the trim. Some chargers are glued together, so a knife is needed to separate and open the charger. Depending on the manufacturer, however, a charger may have been designed to be impossible to open.
2.Remove all of the cord that is coiled up inside the laptop adapter. Use wire cutters to carefully cut and remove the plastic cord without cutting the metal wires inside the cord. Check the entire length of the cord to locate the short, which will be visibly damaged or frayed.
3.Use the wire cutters to remove the portion of the metal wire that is damaged. Shave both remaining ends of the wire down by half and twist them together to reconnect the wire. Cover the exposed metal with electrical tape to bond and protect the wire.hp compaq nc6000 battery
4.Plug the cord into an electrical outlet to check if the charger is working correctly. Recoil the cord back into the adapter and pop both halves back into place. If the charger was glued together, a small amount of glue can be used to secure both of the halves of the adapter.
5.Evaluate the laptop charger if it is still not working correctly. Taking a charger to a laptop technician can be expensive, so purchasing a new charger may be the best option.hp compaq 6910p battery
Tips & WarningsComputer World recommends replacing a laptop cord that is significantly broken or frayed outside of the adapter because it may become a fire hazard. If there is only a small outer fray that does not directly impact the inner cord, then a layer of silicone sealer can be applied to fix it.
Always take care when working on electrical equipment to avoid sustaining serious injuries and burns. If a laptop cord is significantly damaged, replace it to avoid a potential fire hazard.hp compaq 6710b battery
2011年5月23日星期一
Charge a Laptop Battery Without a Charger
Without your AC charger/adapter, you may feel like your laptop is next to worthless. After all, not only do you not have a way to charge the battery in your laptop, you don't even have a way to run your computer via a wall outlet. While new technologies are being developed every day in the area of mobile power solutions and laptop power supplies (including Intel's research into wireless electrical transmissions), there aren't many current alternatives to charging your laptop battery without a charger. If your problem is that you are without your original charger (which is what normally comes with a new laptop), here are some workarounds you can try that will keep your laptop humming. Keep in mind, though, that they cost money and require an advanced purchase, in which case it may be just as economical and convenient to buy a new charger from your laptop's manufacturer.
1.Use a universal power adapter. This is perhaps the most obvious solution to your battery woes. Readily found at most retail outlets that carry electronics, a universal power adapter can range anywhere in price from $30 to $100 (or more, depending on how fancy you get). The adapter comes with multiple tips, one of which will likely fit your laptop's charging port. When plugged in, the adapter will not only power your laptop, but will charge its hp pavilion dv8000 battery as well.
2.Use a universal auto/air adapter. If you're the road-warrior type who spends more time in your car than at a desk, this might be the sensible solution for you. An auto adapter is similar to a regular power adapter, except it has a modified end that plugs into your car's cigarette lighter. The adapter will keep you powered while in your car (or inflight if it's a combination adapter), and will simultaneously charge your laptop so you're ready for those occasions when you do have to leave your car or plane for the real world.
3.Buy an external laptop battery charger. These are standalone devices that do not plug into your laptop. Rather, you take the battery out of your laptop, attach it to the charger, plug the charger into an electrical outlet, and rejuice your battery that way. When fully charged, you reinsert the battery back into your laptop. External chargers are usually brand and model specific, so make sure you get one that matches your laptop's specs. One advantage to an external battery charger is that you can charge spare batteries without tying up your laptop.
Tips & Warnings
Consider using an external laptop battery pack for those times you're caught in a pinch. About the size of a DVD case, these "super batteries" plug into your laptop and can provide up to four or more hours of extra power to your laptop. While they won't charge your laptop's original hp 484784-001 battery, they do offer an excellent alternative power solution.
Don't try to charge your battery by plugging power peripherals into your USB port. Those ports are for powering USB devices only, and could be damaged or start a fire if forced to host unregulated voltages.
1.Use a universal power adapter. This is perhaps the most obvious solution to your battery woes. Readily found at most retail outlets that carry electronics, a universal power adapter can range anywhere in price from $30 to $100 (or more, depending on how fancy you get). The adapter comes with multiple tips, one of which will likely fit your laptop's charging port. When plugged in, the adapter will not only power your laptop, but will charge its hp pavilion dv8000 battery as well.
2.Use a universal auto/air adapter. If you're the road-warrior type who spends more time in your car than at a desk, this might be the sensible solution for you. An auto adapter is similar to a regular power adapter, except it has a modified end that plugs into your car's cigarette lighter. The adapter will keep you powered while in your car (or inflight if it's a combination adapter), and will simultaneously charge your laptop so you're ready for those occasions when you do have to leave your car or plane for the real world.
3.Buy an external laptop battery charger. These are standalone devices that do not plug into your laptop. Rather, you take the battery out of your laptop, attach it to the charger, plug the charger into an electrical outlet, and rejuice your battery that way. When fully charged, you reinsert the battery back into your laptop. External chargers are usually brand and model specific, so make sure you get one that matches your laptop's specs. One advantage to an external battery charger is that you can charge spare batteries without tying up your laptop.
Tips & Warnings
Consider using an external laptop battery pack for those times you're caught in a pinch. About the size of a DVD case, these "super batteries" plug into your laptop and can provide up to four or more hours of extra power to your laptop. While they won't charge your laptop's original hp 484784-001 battery, they do offer an excellent alternative power solution.
Don't try to charge your battery by plugging power peripherals into your USB port. Those ports are for powering USB devices only, and could be damaged or start a fire if forced to host unregulated voltages.
2011年5月18日星期三
Purchase The Best Rechargeable Battery
Think all rechargeable batteries are created equal? Wonder why some are so much more expensive than others? There are other factors besides just the name brand to look at. If your digital camera dies only after a few hours of use, it could be due to the rechargeable batteries your using.
The good news is after reading this e-how you will learn how to get the best rechargeable battery that will have your power hungry devices satisfied and lasting much longer. Look for links at the bottom on some great rechargeable hp batteries I purchased recently and a great charger.
1.The first thing you want to be sure you are getting are the new hybrid Nickel-Metal Hydride (Ni-MH) cells. These are very good for high-drain electronics like digital cameras. A few cool features are they come charged already, so no waiting to charge them after buying. Another great thing is that they hold their charge over many months (unlike regular Ni-MH rechargeables. This is why they are also great for items like remote controls and wireless game controllers as they do not lose their charge as quickly as standard Ni-MH rechargeables.
2.Ok so now you know that you are looking for hybrid Nickel-Metal Hydride (Ni-MH) cells, the next thing you want to look at is the mAh rating. The mAh stands for milli Amp hour, and indicates hp pavilion dv9000 battery's energy storage capacity the higher the rating the better it can handle constant high-drain devices like digital cameras.. Currently 2900 is the highest you will see for AA batteries, 2850 and 2700 are also really good, here is where you might see a price difference play a factor so be sure that you are comparing the same mAh rating.
3.So now what you want to compare are how many times you can charge the batteries, and how long might the charge last over time so you know if you need to use them in 6 months you can rely on them. You might not always see this information listed on the package so you might have to do research, however I am going to list a few here for you.
Hybrio hp pavilion dv1000 battery by Uniross - Hybrios should keep 70% of their charge after a year, and can be charged up to 500 times.
Eneloop Rechargeable Batteries by Sanyo - Eneloop should keep 90% of charged capacity retained after 6 months, and 85% capacity after 12 months at 20 degree Celsius, and can be charged up to 1000 times.
There might be a trade off on the following 3, they are not hybrids, however, they have a very high mAh rating which would mean they would have more power so they last longer for high-drain electronics, so for instance if you were going to take 5 pictures and turn your camera off for a few months, you probably would be ok with the lower mAh rating hybrids, however if you were going to shoot a few hundred pictures over several hours, you would be better with the highest mAh rated hp 431132-002 battery.
POWEREX MH-8AA270-BH 2700mAh AA NiMH Rechargeable Batteries - Ultra high capacity AA batteries offer a super long time run! That's up to 30-40% more than some competitors, and can be charged 1000 times.
Ansmann AA Ni-MH 2850mAh Rechargeable Batteries - NiMH cell with top capacity. The cell is developed for professional use at highest demands. No statement on how many charges.
Delkin Power AA Ni-MH 2900mAh Rechargeable Batteries -
4.Besides the normal chargers, here are a few that have high ratings, and other cool features.
LaCrosse Technology BC-900 Alpha Battery Charger and Recovery System
Ansmann Deluxe "Energy 16" Charger
Maha PowerEx "Ultimate Professional" Charger
With the above information you are now ready to get the best hp pavilion dv7 battery for your money. You and your electronics will be much happier.
The good news is after reading this e-how you will learn how to get the best rechargeable battery that will have your power hungry devices satisfied and lasting much longer. Look for links at the bottom on some great rechargeable hp batteries I purchased recently and a great charger.
1.The first thing you want to be sure you are getting are the new hybrid Nickel-Metal Hydride (Ni-MH) cells. These are very good for high-drain electronics like digital cameras. A few cool features are they come charged already, so no waiting to charge them after buying. Another great thing is that they hold their charge over many months (unlike regular Ni-MH rechargeables. This is why they are also great for items like remote controls and wireless game controllers as they do not lose their charge as quickly as standard Ni-MH rechargeables.
2.Ok so now you know that you are looking for hybrid Nickel-Metal Hydride (Ni-MH) cells, the next thing you want to look at is the mAh rating. The mAh stands for milli Amp hour, and indicates hp pavilion dv9000 battery's energy storage capacity the higher the rating the better it can handle constant high-drain devices like digital cameras.. Currently 2900 is the highest you will see for AA batteries, 2850 and 2700 are also really good, here is where you might see a price difference play a factor so be sure that you are comparing the same mAh rating.
3.So now what you want to compare are how many times you can charge the batteries, and how long might the charge last over time so you know if you need to use them in 6 months you can rely on them. You might not always see this information listed on the package so you might have to do research, however I am going to list a few here for you.
Hybrio hp pavilion dv1000 battery by Uniross - Hybrios should keep 70% of their charge after a year, and can be charged up to 500 times.
Eneloop Rechargeable Batteries by Sanyo - Eneloop should keep 90% of charged capacity retained after 6 months, and 85% capacity after 12 months at 20 degree Celsius, and can be charged up to 1000 times.
There might be a trade off on the following 3, they are not hybrids, however, they have a very high mAh rating which would mean they would have more power so they last longer for high-drain electronics, so for instance if you were going to take 5 pictures and turn your camera off for a few months, you probably would be ok with the lower mAh rating hybrids, however if you were going to shoot a few hundred pictures over several hours, you would be better with the highest mAh rated hp 431132-002 battery.
POWEREX MH-8AA270-BH 2700mAh AA NiMH Rechargeable Batteries - Ultra high capacity AA batteries offer a super long time run! That's up to 30-40% more than some competitors, and can be charged 1000 times.
Ansmann AA Ni-MH 2850mAh Rechargeable Batteries - NiMH cell with top capacity. The cell is developed for professional use at highest demands. No statement on how many charges.
Delkin Power AA Ni-MH 2900mAh Rechargeable Batteries -
4.Besides the normal chargers, here are a few that have high ratings, and other cool features.
LaCrosse Technology BC-900 Alpha Battery Charger and Recovery System
Ansmann Deluxe "Energy 16" Charger
Maha PowerEx "Ultimate Professional" Charger
With the above information you are now ready to get the best hp pavilion dv7 battery for your money. You and your electronics will be much happier.
2011年5月9日星期一
How to Fix Your Mac's Battery
Apple Macintosh's laptop batteries are known for having issues. The computer might not turn on or awake from sleep, the battery might not charge, the battery might appear to be full but then the computer shuts down, or it might start bulging, which poses a possible safety risk. In this article, you'll learn how to fix your Mac's battery- or what to do if you can't fix it. You should do these steps in order.
1.The first thing you might try to fix your Mac's battery is to simply put your Mac to sleep and then wake it. If this doesn't work, restart your Mac.
2.If reawakening and restarting doesn't fix your Mac's apple a1175 battery, be sure the AC adapter is unplugged, shut down your Mac, take the battery out and then reinsert the battery. Restart.
3.If the above two steps do not work you should reset your Mac's SMC. The SMC is the System's Management Controller, and among other things, it controls your laptop's power functions. You should only do this if the above steps do not work.
*If You Have a Removable Battery
For Macs with a removable battery, be sure your AC adapter is unplugged and shut down your computer. Remove the laptop's battery. Hold the laptop's power button down and count to five. Let go, reinsert the Mac battery, and restart your computer.
*If Your Mac Laptop Does Not Have a Removable Battery
Macs without a removable apple a1185 battery must reset their SMC differently. To do this: Make sure your laptop is shut down. Plug in the AC adapter to both the wall and your computer. Press the following buttons at the same time: Shift + Control + Option + the power button. (This must be done on the original keyboard, not a peripheral one.) Release all of the buttons at the same time. Turn your Mac back on.
*If You Have a Mac Pro or Intel-based iMac, Mac mini, Xserve
For these specific computers, make sure the computer is shut down. Unplug the power cord, press the power button down and count to five. Release the button, plug the computer back in, and turn your computer back on.
4.If these options do not work for you and do not fix your Mac's battery, it is time to contact the Apple store. In many cases, even if your laptop's battery is not under warranty anymore, Apple will place your battery anyway as they pose a safety risk, especially if the apple powerbook g4 12 battery is bulging. Simply take your computer into the closest Apple store. You can find a list of retail Apple stores at the link below, in the resources section of this article. If there is not an Apple store close to you, contact Apple at 1-800-MY-APPLE.
1.The first thing you might try to fix your Mac's battery is to simply put your Mac to sleep and then wake it. If this doesn't work, restart your Mac.
2.If reawakening and restarting doesn't fix your Mac's apple a1175 battery, be sure the AC adapter is unplugged, shut down your Mac, take the battery out and then reinsert the battery. Restart.
3.If the above two steps do not work you should reset your Mac's SMC. The SMC is the System's Management Controller, and among other things, it controls your laptop's power functions. You should only do this if the above steps do not work.
*If You Have a Removable Battery
For Macs with a removable battery, be sure your AC adapter is unplugged and shut down your computer. Remove the laptop's battery. Hold the laptop's power button down and count to five. Let go, reinsert the Mac battery, and restart your computer.
*If Your Mac Laptop Does Not Have a Removable Battery
Macs without a removable apple a1185 battery must reset their SMC differently. To do this: Make sure your laptop is shut down. Plug in the AC adapter to both the wall and your computer. Press the following buttons at the same time: Shift + Control + Option + the power button. (This must be done on the original keyboard, not a peripheral one.) Release all of the buttons at the same time. Turn your Mac back on.
*If You Have a Mac Pro or Intel-based iMac, Mac mini, Xserve
For these specific computers, make sure the computer is shut down. Unplug the power cord, press the power button down and count to five. Release the button, plug the computer back in, and turn your computer back on.
4.If these options do not work for you and do not fix your Mac's battery, it is time to contact the Apple store. In many cases, even if your laptop's battery is not under warranty anymore, Apple will place your battery anyway as they pose a safety risk, especially if the apple powerbook g4 12 battery is bulging. Simply take your computer into the closest Apple store. You can find a list of retail Apple stores at the link below, in the resources section of this article. If there is not an Apple store close to you, contact Apple at 1-800-MY-APPLE.
2011年5月4日星期三
Discharging at High and Low Temperatures
Like humans, batteries function best at room temperature, and any deviation towards hot and cold changes the performance and/or longevity. Operating a battery at elevated temperatures momentarily improves performance by lowering the internal resistance and speeding up the chemical metabolism, but such a condition shortens service life if allowed to continue for a long period of time. Some manufacturers of lead acid batteries make use of the improved performance at warmer temperatures and specify the batteries at a toasty 27°C (80°F).
Cold temperature increases the internal resistance and diminishes the capacity. Batteries that would provide 100 percent capacity at 27°C (80°F) will typically deliver only 50 percent at –18°C (0°F). The capacity decrease is linear with temperature.
Li-ion also performs better at high temperatures than at low ones. Heat lowers the internal resistance but this stresses the battery. Warming a dying flashlight or cellular phone battery in your jean pocket might provide additional runtime in the winter. As all drivers in cold countries know, a warm battery cranks the car engine easier than a cold one.
The dry solid polymer hp pavilion dv6 battery uses heat to promote ion flow in what is called a “true plastic battery.” The battery requires a core temperature of 60 to 100°C (140 to 212°F) to become conductive. The dry solid polymer has found a niche market for stationary power applications in warm climates where heat serves as a catalyst rather than a disadvantage. Built-in heating elements keep the battery operational at all times. High battery cost and safety concerns have limited the application of this technology. The more common Li-polymer uses moist electrolyte to enhance conductivity, as discussed earlier. Read more about the Lithium-polymer battery.
Batteries achieve optimum service life if used at 20°C (68°F) or slightly below, and nickel-based chemistries degrade rapidly when cycled at high ambient temperatures. If, for example, a battery operates at 30°C (86°F) instead of a more moderate room temperature, the cycle life is reduced by 20 percent. At 40°C (104°F), the loss jumps to a whopping 40 percent, and if charged and discharged at 45°C (113°F), the cycle life is only half of what can be expected if used at 20°C (68°F).
The performance of all battery chemistries drops drastically at low temperatures. At –20°C (–4°F) most nickel-, lead- and lithium-based batteries stop functioning. Although NiCd can go down to –40°C (-40°F), the permissible discharge is only 0.2C (5-hour rate). Specially built Li- ion brings the operating temperature down to –40°C, but only on discharge and at a reduced discharge. With lead acid we have the danger of the electrolyte freezing, which can crack the enclosure. Lead acid freezes more easily with a low charge when the specific gravity of the electrolyte is more like water.
Cell matching by using cells of similar capacity plays an important role when discharging at low temperature under heavy load. Since the cells in a hp pavilion dv7 battery pack can never be perfectly matched, a negative voltage potential can occur across a weaker cell on a multi-cell pack if the discharge is allowed to continue beyond a safe cut-off point. Known as cell reversal, the weak cell suffers damage to the point of developing a permanent electrical short. The larger the cell-count, the greater the likelihood that a cell might reverse under load. Over-discharge at a heavy load and low temperature is a large contributor to battery failure of cordless power tools, especially nickel-based packs; Li-ion packs come with protection circuits and the failure rate is lower. Read about Cell Mismatch and Balancing.
Users of electric vehicles need to understand that the driving distance specified per charge is given under normal temperature; frigid cold will sharply reduce the available mileage. Using electricity for cabin heating is not the only cause for the shorter driving distance between charging; the hp pavilion dv8 battery performance is reduced when cold.
Cold temperature increases the internal resistance and diminishes the capacity. Batteries that would provide 100 percent capacity at 27°C (80°F) will typically deliver only 50 percent at –18°C (0°F). The capacity decrease is linear with temperature.
Li-ion also performs better at high temperatures than at low ones. Heat lowers the internal resistance but this stresses the battery. Warming a dying flashlight or cellular phone battery in your jean pocket might provide additional runtime in the winter. As all drivers in cold countries know, a warm battery cranks the car engine easier than a cold one.
The dry solid polymer hp pavilion dv6 battery uses heat to promote ion flow in what is called a “true plastic battery.” The battery requires a core temperature of 60 to 100°C (140 to 212°F) to become conductive. The dry solid polymer has found a niche market for stationary power applications in warm climates where heat serves as a catalyst rather than a disadvantage. Built-in heating elements keep the battery operational at all times. High battery cost and safety concerns have limited the application of this technology. The more common Li-polymer uses moist electrolyte to enhance conductivity, as discussed earlier. Read more about the Lithium-polymer battery.
Batteries achieve optimum service life if used at 20°C (68°F) or slightly below, and nickel-based chemistries degrade rapidly when cycled at high ambient temperatures. If, for example, a battery operates at 30°C (86°F) instead of a more moderate room temperature, the cycle life is reduced by 20 percent. At 40°C (104°F), the loss jumps to a whopping 40 percent, and if charged and discharged at 45°C (113°F), the cycle life is only half of what can be expected if used at 20°C (68°F).
The performance of all battery chemistries drops drastically at low temperatures. At –20°C (–4°F) most nickel-, lead- and lithium-based batteries stop functioning. Although NiCd can go down to –40°C (-40°F), the permissible discharge is only 0.2C (5-hour rate). Specially built Li- ion brings the operating temperature down to –40°C, but only on discharge and at a reduced discharge. With lead acid we have the danger of the electrolyte freezing, which can crack the enclosure. Lead acid freezes more easily with a low charge when the specific gravity of the electrolyte is more like water.
Cell matching by using cells of similar capacity plays an important role when discharging at low temperature under heavy load. Since the cells in a hp pavilion dv7 battery pack can never be perfectly matched, a negative voltage potential can occur across a weaker cell on a multi-cell pack if the discharge is allowed to continue beyond a safe cut-off point. Known as cell reversal, the weak cell suffers damage to the point of developing a permanent electrical short. The larger the cell-count, the greater the likelihood that a cell might reverse under load. Over-discharge at a heavy load and low temperature is a large contributor to battery failure of cordless power tools, especially nickel-based packs; Li-ion packs come with protection circuits and the failure rate is lower. Read about Cell Mismatch and Balancing.
Users of electric vehicles need to understand that the driving distance specified per charge is given under normal temperature; frigid cold will sharply reduce the available mileage. Using electricity for cabin heating is not the only cause for the shorter driving distance between charging; the hp pavilion dv8 battery performance is reduced when cold.
2011年4月29日星期五
Industrial Applications
Industrial applications have unique power needs and the choice of battery is important. While consumer products demand high energy density to obtain slim and elegant designs, industry focuses on durability and reliability. Industrial batteries are commonly bulkier than those used in consumer products but achieve a longer service life.
Batteries are electro-chemical devices that convert higher-level active materials into an alternate state during discharge. The speed of such transaction determines the load characteristics of a battery. Also referred to as concentration polarization, the nickel and lithium-based batteries are superior to lead-based batteries in reaction speed. This attribute reflects in good load characteristics.
Discharge loads range from a low and steady current flow of a flashlight to intermittent high current bursts in a power tool, to sharp current pulses on digital communications equipment, laptops and cameras. In this paper we evaluate how the various battery chemistries perform in a given application.
What's the best battery for video cameras?
Nickel-cadmium batteries continue to power a large percentage of professional cameras. This battery provided reliable service and performs well at low temperature. nickel-cadmium is one of the most enduring batteries in terms of service life but has only moderate energy density and needs a periodic full discharge.
The need for longer runtimes is causing a switch to nickel-metal-hydride. This battery offers up to 50% more energy than nickel-cadmium. However, the high current spikes drawn by digital cameras have a negative affect and the nickel-metal-hydride dell inspiron 1520 battery suffers from short service life.
There is a trend towards lithium-ion. Among rechargeables, this chemistry has the highest energy density and is lightweight. A steep price tag and the inability to provide high currents are negatives.
The 18650 cylindrical lithium-ion cell offers the most economical power source. "18" defines the cell's diameter in millimeters and "650" the length. No other lithium-ion cell, including prismatic or polymer types, offers a similar low cost-per-watt ratio.
Over the years, several cell versions of 18650 cells with different Ah ratings have emerged, ranging from 1.8Ah to well above 2Ah. The cells with moderate capacities offer better temperature performance, enable higher currents and provide a longer service life than the souped up versions.
The typical 18650 for industrial use is rated at 2Ah at 3.60 volts. Four cells are connected in series to obtain the roughly 15 volts needed for the cameras. Paralleling the cells increases the current handling by about 2A per cell. Three cells in parallel would provide about 6A of continuous power. Four cells in series and three in parallel is a practical limit for the 18650 system.
Lithium-ion requires a protection circuit to provide safe operations under all circumstances. Each cell in series is protected against voltage peaks and dips. In addition, the protection circuit limits each cell to a current about 2A. Even if paralleled, the current of a lithium-ion pack is not high enough to drive digital cameras requiring 10 to 15A peak current. Tests conducted at Cadex Electronics have shown that the 18650 allows short current peaks above the 2A/cell limit. This would allow the use of lithium-ion on digital cameras, provided the current bursts are limited to only a few seconds.
What's the best battery for still cameras?
The power requirement of a professional digital camera is sporadic in nature. Much battery power is needed to take snapshots, some with a powerful flash. To view the photo, the backlit color display draws additional power. Transmitting a high-resolution image over the air depletes another portion of the energy reserve.
Most non-professional cameras use a primary lithium hp battery. This battery type provides the highest energy density but cannot be recharged. This is a major drawback for professional use. Rechargeable batteries are the answer and lithium-ion fits the bill but faces similar challenges to the video cameras.
What is the best battery for medical devices?
One of the most energy-hungry portable medical devices is the heart defibrillator. The battery draws in excess of 10 amperes during preparation stages. Several shocks may be needed to get the patient's heart going again. The battery must not hamper the best possible patient care.
Most defibrillators are powered by nickel-cadmium. nickel-metal-hydride is also being used but there is concern of short service life. In a recent study, however, it was observed that a defibrillator battery cycles far less than expected. Instead of the anticipated 200 cycles after two years of seemingly heavy use, less than 60 cycles had been delivered on the battery examined. 'Smart' battery technology makes such information possible. With fewer cycles needed, the switch to higher energy-dense batteries becomes a practical alternative.
Sealed lead-acid batteries are often used to power defibrillators intended for standby mode. Although bulky and heavy, the Lead-acid has a low self-discharge and can be kept in prolonged ready mode without the need to recharge. Lead-acid performs well on high current spurts. During the rest periods the dell inspiron 9400 battery disperses the depleted acid concentrations back into the electrode plate. Lead-acid would not be suitable for a sustained high load.
The medical industry is moving towards lithium-ion. The robust and economical 18650 cells make this possible. The short but high current spurts needed for defibrillators are still a challenge. Paralleling the cells and adding current-limiting circuits that allow short spikes of high current will help overcome this hurdle.
What is the best battery for power tools?
Power tools require up to 50 amperes of current and operate in an unfriendly environment. The tool must perform at sub zero temperatures and endure in high heat. The batteries must also withstand shock and vibration.
Most power tools are equipped with nickel-cadmium batteries. nickel-metal-hydride has been tried with limited success. Longevity is a problem but new designs have improved. lithium-ion is too delicate and could not provide the high amperage. Lead-acid is too bulky and lacks persistent power delivery. The power tool has simply no suitable alternatives to the rugged and hard-working nickel-cadmium.
In an attempt to pack more energy into power tools, the power tool battery voltage is increased. Because of heavy current and application at low temperatures, cell matching is important. Cell matching becomes more critical as the number of cell connected in series increases. A weak cell holds less capacity and is discharged more quickly than the strong ones. This imbalance causes cell reversal on the weak cell if the battery is discharged at high current below 1V/cell. An electrical short occurs in the weak cell if exposed to reverse current and the pack needs to be replaced. The higher the battery voltage, the more likely will a weak cell get damaged.
Batteries are electro-chemical devices that convert higher-level active materials into an alternate state during discharge. The speed of such transaction determines the load characteristics of a battery. Also referred to as concentration polarization, the nickel and lithium-based batteries are superior to lead-based batteries in reaction speed. This attribute reflects in good load characteristics.
Discharge loads range from a low and steady current flow of a flashlight to intermittent high current bursts in a power tool, to sharp current pulses on digital communications equipment, laptops and cameras. In this paper we evaluate how the various battery chemistries perform in a given application.
What's the best battery for video cameras?
Nickel-cadmium batteries continue to power a large percentage of professional cameras. This battery provided reliable service and performs well at low temperature. nickel-cadmium is one of the most enduring batteries in terms of service life but has only moderate energy density and needs a periodic full discharge.
The need for longer runtimes is causing a switch to nickel-metal-hydride. This battery offers up to 50% more energy than nickel-cadmium. However, the high current spikes drawn by digital cameras have a negative affect and the nickel-metal-hydride dell inspiron 1520 battery suffers from short service life.
There is a trend towards lithium-ion. Among rechargeables, this chemistry has the highest energy density and is lightweight. A steep price tag and the inability to provide high currents are negatives.
The 18650 cylindrical lithium-ion cell offers the most economical power source. "18" defines the cell's diameter in millimeters and "650" the length. No other lithium-ion cell, including prismatic or polymer types, offers a similar low cost-per-watt ratio.
Over the years, several cell versions of 18650 cells with different Ah ratings have emerged, ranging from 1.8Ah to well above 2Ah. The cells with moderate capacities offer better temperature performance, enable higher currents and provide a longer service life than the souped up versions.
The typical 18650 for industrial use is rated at 2Ah at 3.60 volts. Four cells are connected in series to obtain the roughly 15 volts needed for the cameras. Paralleling the cells increases the current handling by about 2A per cell. Three cells in parallel would provide about 6A of continuous power. Four cells in series and three in parallel is a practical limit for the 18650 system.
Lithium-ion requires a protection circuit to provide safe operations under all circumstances. Each cell in series is protected against voltage peaks and dips. In addition, the protection circuit limits each cell to a current about 2A. Even if paralleled, the current of a lithium-ion pack is not high enough to drive digital cameras requiring 10 to 15A peak current. Tests conducted at Cadex Electronics have shown that the 18650 allows short current peaks above the 2A/cell limit. This would allow the use of lithium-ion on digital cameras, provided the current bursts are limited to only a few seconds.
What's the best battery for still cameras?
The power requirement of a professional digital camera is sporadic in nature. Much battery power is needed to take snapshots, some with a powerful flash. To view the photo, the backlit color display draws additional power. Transmitting a high-resolution image over the air depletes another portion of the energy reserve.
Most non-professional cameras use a primary lithium hp battery. This battery type provides the highest energy density but cannot be recharged. This is a major drawback for professional use. Rechargeable batteries are the answer and lithium-ion fits the bill but faces similar challenges to the video cameras.
What is the best battery for medical devices?
One of the most energy-hungry portable medical devices is the heart defibrillator. The battery draws in excess of 10 amperes during preparation stages. Several shocks may be needed to get the patient's heart going again. The battery must not hamper the best possible patient care.
Most defibrillators are powered by nickel-cadmium. nickel-metal-hydride is also being used but there is concern of short service life. In a recent study, however, it was observed that a defibrillator battery cycles far less than expected. Instead of the anticipated 200 cycles after two years of seemingly heavy use, less than 60 cycles had been delivered on the battery examined. 'Smart' battery technology makes such information possible. With fewer cycles needed, the switch to higher energy-dense batteries becomes a practical alternative.
Sealed lead-acid batteries are often used to power defibrillators intended for standby mode. Although bulky and heavy, the Lead-acid has a low self-discharge and can be kept in prolonged ready mode without the need to recharge. Lead-acid performs well on high current spurts. During the rest periods the dell inspiron 9400 battery disperses the depleted acid concentrations back into the electrode plate. Lead-acid would not be suitable for a sustained high load.
The medical industry is moving towards lithium-ion. The robust and economical 18650 cells make this possible. The short but high current spurts needed for defibrillators are still a challenge. Paralleling the cells and adding current-limiting circuits that allow short spikes of high current will help overcome this hurdle.
What is the best battery for power tools?
Power tools require up to 50 amperes of current and operate in an unfriendly environment. The tool must perform at sub zero temperatures and endure in high heat. The batteries must also withstand shock and vibration.
Most power tools are equipped with nickel-cadmium batteries. nickel-metal-hydride has been tried with limited success. Longevity is a problem but new designs have improved. lithium-ion is too delicate and could not provide the high amperage. Lead-acid is too bulky and lacks persistent power delivery. The power tool has simply no suitable alternatives to the rugged and hard-working nickel-cadmium.
In an attempt to pack more energy into power tools, the power tool battery voltage is increased. Because of heavy current and application at low temperatures, cell matching is important. Cell matching becomes more critical as the number of cell connected in series increases. A weak cell holds less capacity and is discharged more quickly than the strong ones. This imbalance causes cell reversal on the weak cell if the battery is discharged at high current below 1V/cell. An electrical short occurs in the weak cell if exposed to reverse current and the pack needs to be replaced. The higher the battery voltage, the more likely will a weak cell get damaged.
2011年4月27日星期三
Battery Fuel Gauge
One of the main tasks of the smart battery is to establish communication between the battery and user. A fuel gauge that indicates state-of-charge is part of this effort. When pressing the TEST button on a fully charged SMBus battery, all signal lights illuminate. On a partially discharged battery, half the lights illuminate, and on an empty battery all lights remain dark or a red light appears. Figure 1 shows a fuel gauge of a battery that is 75 percent charged, with three lights glowing.
While the SoC information displayed on a high quality battery or computer screen is helpful to the user, it does not assure sufficient runtime, because the fuel gauge resets to 100 percent on a full recharge regardless of how much capacity the battery can store. A serious miscount occurs if an aged battery shows 100 percent SoC while the battery’s ability to hold charge has dropped to 50 percent or less. We ask, “100 percent of what?” If, for example, 100 percent of a good battery results in a four-hour runtime, the same indication with a battery holding half the capacity would run for only two hours. The user should know that the fuel gauge only shows SoC and capacity is missing.
Other than using coulomb counting and measuring internal resistance, there is no reliable method to calculate the state-of-health (SoH) of a battery; current technologies provide only rough estimations. However, there is a way to display the capacity of a smart battery digitally.
At time of manufacture, the SMBus battery is programmed with a specified capacity, which is 100 percent by default, and the toshiba satellite a350 battery keeps this information as permanent data. With each full charge, the battery resets to the charge flag; and during discharge the coulomb counter measures the consumed energy. A perfect battery would deliver 100 percent on a calibrated fuel gauge. As the battery ages and the capacity drops, the delivered energy between charges decreases. The discrepancy between the factory-set 100 percent and the delivered coulombs after a full charge can thus determine the battery capacity.
The SoC and capacity information can be shown on a linear display using colored LEDs. The green lights indicate the usable capacity; the empty part of the battery is marked with dark LEDs; and the unusable part is shown with red LEDs. Figure 2 illustrates a tri-state fuel gauge. Alternatively, the results can be a shown on a digital display.
Figure 2: Tri-state fuel gauge.The tri-state fuel gauge reads the “learned” battery information on the SMBus and displays it on a multi colored LED bar. The illustration shows a partially discharged toshiba satellite a200 battery of 50% SoC with 20% empty and 30% unusable.
Courtesy of Cadex
Installed in an SMBus charger, the tri-state fuel gauge indicates the usable capacity of SMBus compatible batteries and gives the user a clear indication of when to retire a pack. The pass/fail level is user-selectable — at, say, 60, 70 or 80 percent — depending on the minimum required performance level. A failed battery prompts the user to first calibrate the battery. If the charge/discharge/charge cycle did not raise the capacity to the set target level, a red light on the charger indicates a fail. A lit green ready light always assures that the battery has been successfully charged and meets the capacity requirements. (Cadex offered such a charger but the buyers did not appreciate the benefit.)
Cars with electric propulsion systems use similar fuel-gauge technologies to determine the state-of-charge and state-of-function of the battery. The challenge is in knowing how far a vehicle can travel with a fully charged battery in various ambient conditions. A tailwind on a sunny day is more forgiving than a headwind with snow. The aging of a toshiba pa3594u-1brs battery adds to the challenge and the fuel gauge will lose accuracy over time. Showing 30 minutes of remaining runtime and then shutting down, as is common with laptops, will not be easily forgiven with the electric vehicle.
 | Figure 1: State-of-charge readout of a “smart” battery Signal lights indicate the battery SoC when pressing the TEST button. Courtesy of Cadex |
While the SoC information displayed on a high quality battery or computer screen is helpful to the user, it does not assure sufficient runtime, because the fuel gauge resets to 100 percent on a full recharge regardless of how much capacity the battery can store. A serious miscount occurs if an aged battery shows 100 percent SoC while the battery’s ability to hold charge has dropped to 50 percent or less. We ask, “100 percent of what?” If, for example, 100 percent of a good battery results in a four-hour runtime, the same indication with a battery holding half the capacity would run for only two hours. The user should know that the fuel gauge only shows SoC and capacity is missing.
Other than using coulomb counting and measuring internal resistance, there is no reliable method to calculate the state-of-health (SoH) of a battery; current technologies provide only rough estimations. However, there is a way to display the capacity of a smart battery digitally.
At time of manufacture, the SMBus battery is programmed with a specified capacity, which is 100 percent by default, and the toshiba satellite a350 battery keeps this information as permanent data. With each full charge, the battery resets to the charge flag; and during discharge the coulomb counter measures the consumed energy. A perfect battery would deliver 100 percent on a calibrated fuel gauge. As the battery ages and the capacity drops, the delivered energy between charges decreases. The discrepancy between the factory-set 100 percent and the delivered coulombs after a full charge can thus determine the battery capacity.
The SoC and capacity information can be shown on a linear display using colored LEDs. The green lights indicate the usable capacity; the empty part of the battery is marked with dark LEDs; and the unusable part is shown with red LEDs. Figure 2 illustrates a tri-state fuel gauge. Alternatively, the results can be a shown on a digital display.
Figure 2: Tri-state fuel gauge.The tri-state fuel gauge reads the “learned” battery information on the SMBus and displays it on a multi colored LED bar. The illustration shows a partially discharged toshiba satellite a200 battery of 50% SoC with 20% empty and 30% unusable.
Courtesy of Cadex
Installed in an SMBus charger, the tri-state fuel gauge indicates the usable capacity of SMBus compatible batteries and gives the user a clear indication of when to retire a pack. The pass/fail level is user-selectable — at, say, 60, 70 or 80 percent — depending on the minimum required performance level. A failed battery prompts the user to first calibrate the battery. If the charge/discharge/charge cycle did not raise the capacity to the set target level, a red light on the charger indicates a fail. A lit green ready light always assures that the battery has been successfully charged and meets the capacity requirements. (Cadex offered such a charger but the buyers did not appreciate the benefit.)
Cars with electric propulsion systems use similar fuel-gauge technologies to determine the state-of-charge and state-of-function of the battery. The challenge is in knowing how far a vehicle can travel with a fully charged battery in various ambient conditions. A tailwind on a sunny day is more forgiving than a headwind with snow. The aging of a toshiba pa3594u-1brs battery adds to the challenge and the fuel gauge will lose accuracy over time. Showing 30 minutes of remaining runtime and then shutting down, as is common with laptops, will not be easily forgiven with the electric vehicle.
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