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-------------------------------------------------------------- This story was printed from CNET Asia. --------------------------------------------------------------
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All about laptop batteries
By CNET Australia
05/05/2009 URL: http://asia.cnet.com/digitalliving/tips/0,3800004921,62053780,00.htm
The simple fact of notebook life is that systems just don't run for as long on their batteries as we'd like--even long-lived notebooks such as Sony's Vaio VGN-TT17GN/X lasts up to only 6 hours on a single charge.
Battery technologies explainedWith four battery technologies onstage and one waiting in the wings, there's sure to be a battery to suit your needs.Although all batteries are not created equal, they all have the ability to turn chemical energy into electric current to power electronic devices--from tiny digital music players to big notebooks. As with the battery in a car, a chemical reaction inside a notebook's battery frees electrons to flow from the positive terminal to the negative terminal, creating enough current to run the device. That was then The old-timer of mobile battery technologies is the nickel-cadmium cell (NiCd), once the mainstay of laptop design. Unfortunately, NiCd cells can carry only enough power to run a system for about an hour, and they contain toxic cadmium which makes them hard to dispose of. Despite their ability to be recharged about 1,000 times, nickel-cadmium cell batteries also suffer from something called "memory effects"; over time, they lose the ability to hold a complete charge. Luckily, lighter and more powerful battery designs have surpassed the NiCd, and today, NiCds are used mostly in toys and inexpensive cordless phones. About a decade ago, most notebook makers switched to nickel-metal-hydride batteries (NiMH). Not only can these batteries hold about 40 percent more power, they aren't as susceptible to memory problems as NiCds are, and they are more environmentally friendly. On the downside, you can recharge NiMHonly about 200 times versus 400 charge cycles for newer designs.
This is now Today, the lithium-ion cell (also known as Li-ion), which holds roughly twice the capacity of a nickel-cadmium battery, rules the notebook battery roost. Used on most laptops, handhelds and mobile phones, lithium-ion technology can hold a lot of power, but its exotic materials make it expensive. Part of the credit for its success goes to a tiny controller chip embedded in each battery that adjusts how quickly the battery discharges and prevents it from overcharging. Lithium polymer Lithium-polymer (Li-poly) technology has already made its way into high-end mobile phones, handhelds and notebooks. Extremely light and malleable, these batteries are capable of providing nearly as much power as lithium-ion cells, but can also be shaped to fit into a device's hidden nooks and crannies.
Batteries versus fuel cellsThe traditional battery's days may be numbered. Thanks to recent advances in fuel cell technology, your next notebook (or even the one after that) could run for days on a single charge. These next-generation batteries, which contain chemicals such as methanol stored in small tanks, certainly aren't your average power source. More like tiny chemical plants, different types of fuel cells are currently used in space shuttles, experimental eco-friendly cars and small power plants. NEC is developing a fuel cell for a portable that could provide a mind-boggling 40 hours of battery life.So how does a fuel cell work? "The fuel cell is based on the reverse principle of water electrolysis... [Fuel cells] work by having hydrogen and oxygen react to generate electricity," said Yoshimi Kubo to CNET, senior research manager overseeing NEC's project to create a fuel cell-powered notebook. Methanol, or methyl alcohol, is NEC's fuel of choice, and Kubo has created a prototype notebook that can run for 5 hours on about a pint of fuel (10 percent concentration). When the tank is dry, forget about a power cable because the fuel cell wants more methanol. Just pour in a small bottle of fuel, and it's ready to go. Rather than carry a bagful of batteries on a long flight, all you'll need is a bottle of methanol--but be careful, methanol is a poison. For now, packaging is the biggest obstacle that fuel cells face. "Currently, the fuel cell cannot fit into a standard battery location," Kubo said. "It will need further development in order to fit into a notebook, and miniaturization is a challenge we're facing." According to Kubo, NEC is attacking this problem from three directions: Upping the concentration of methanol; using a low-power processor; and increasing the tank size. Fuel-cell-powered handheld In contrast, Hitachi is thinking smaller. Along with Tokai, a Japanese maker of cigarette lighters, Hitachi is working on a fuel cell-powered handheld. About the size of an AA-sized battery, the fuel cell contains 57g of 20 percent methanol fuel and can power a handheld computer for 6 to 8 hours. A couple of prototypes have already been showcased. One of them, the MTI Micro GPS, is capable of lasting up to 60 hours. A fuel cell charger by Lilliputian Systems is so close to production, it claims the first products will hit store shelves in 2010. All these adds up to big business over the next decade, according to Daniel Benjamin, a marketing analyst at Allied Business Intelligence, based in Oyster Bay, New York. "Fuel cells will provide a clean source of energy, but cost and technical issues will pose significant barriers." He told CNET. Despite this, he said that by 2011, there could be 200 million fuel cells of all sizes and capacities sold, powering everything from MP3 players to notebooks. By then, we may be able to kiss our current batteries goodbye, along with the eternal search for a power outlet to charge them--although finding fuel may create quite another problem.
Power and performanceThe laptop you buy may help determine the amount of uptime you can expect on an air flight. How come? Even though the CPU consumes about half the notebook's total power, recent advances in processor technology have eased the burden placed on a system's battery. Now, thanks to Intel's Core 2 Duo and Centrino 2 technology, for instance, portables can run faster and longer on the same batteries they used to use. Here's the lowdown on which processors let notebooks last the longest.Intel Core 2 Duo (part of the Centrino 2 package) Without a doubt, the Core 2 Duo is the batterylife champ. With two processor cores and the ability to streamline operations, it balances raw power with extensive battery life. Toss in an Intel-made Wi-Fi radio and an Intel chipset, and the Core 2 Duo is part of the Centrino 2 triad. Running at up to 2.53GHz, Core 2 Duo notebooks run rings around the competition, and many offer over 4 hours of battery life. Intel Core Solo Intel's Core Solo processor is very similar to the Core Duo. However, the former uses single as opposed to dual processor cores. This results in decreased raw performance but also means the chip consumes less power--5.5-27W compared with the Core Duo's 15-31W. The Core Solo runs at speeds of up to 1.83GHz Intel Atom With a top speed of up to 1.66GHz and a small 512KB L2 cache, these processors trade performance for size and battery life and are mainly used in Netbooks. With a power consumption of 2.5 - 8W, suboportables such as the Asus Eee PC 1000He can last up to an impressive 11 hours before requiring a recharge. AMD Turion 64 X2 Ultra The Turion 64 X2 Ultra is the Core 2 Duo's main competitor. Like Intel's version, this AMD processor offers two cores for increased performance while multitasking. It also boasts AMD's PowerNow! power management technology which the chipmaker says can extend system battery life by up to 65 percent. Built-in antivirus protection is included, and the processor comes in speeds of up to 2.4GHz. Its power consumption is slightly higher than that seen on Core Duo processors, and ranges from 32 to 35 watts. AMD Turion 64 The Turion 64 is a cut-down version of the Turion 64 X2. The Turion 64 offers all of the same features as the X2, but like Intel's Core Solo, includes only a single processor core. Its power consumption ranges from 25 to 35 watts, with speeds of up to 2.4GHz.
10 tips for the power-hungryWith a little power conservation and some smart moves, you can greatly improve your laptop's battery life. Here are our top 10 tips for getting the most out of your batteries.1. Think small If extra-long battery life matters to you, forget about that huge, 17-inch notebook with the top-speed processor--it probably won't run for more than 2 hours. When you're buying your next portable, think small and consider an ultraportable or a thin-and-light system. An Intel Core 2 Duo processor uses about half as much power as a Pentium 4, a 12.1-inch screen uses 50 percent less juice than a 17-inch model, and getting a 4,200rpm hard drive instead of a 5,400rpm model can mean an extra 15 to 20 minutes of battery life. 2. Control your power Adjust your notebook's power settings to find a comfort zone where you're using as little power as possible with no interference in your computing tasks. The path to the control panel will vary according to your operating system and setup, but for Windows XP Home and Pro users, follow these steps: Go to Start/Control Panel/Performance And Maintenance/Power Options. Set the LCD screen to go off after 5 minutes of inactivity, let the hard drive stay active for 20 minutes, and store the system's contents in RAM when it shuts down. If your laptop goes to sleep too soon, adjust the settings. 3. Dim all the lights Your LCD's backlight uses up to 10 watts of power, a huge battery drain. Lower the display panel's brightness to where it's comfortable to view without squinting. In addition to the Power Options settings detailed above, most notebooks have convenient function keys for controlling screen brightness. Look for the function key with the brightness icon and a down arrow next to it (this is the F6 key on many systems). Also, some new portables, such as Apple's MacBook Pro adjusts the LCD's brightness to suit the conditions. 4. Be battery smart Know how much power remains by checking the battery power icon in the system tray. Or buy a machine with a battery that features a charge-level LED gauge on the battery itself so that you can just flip over the system to see how much battery life remains. If you really want to see tons of detail on what your battery is doing and how much life is left, take battery monitoring to the next level with PassMark's BatteryMon utility. 5. Double or triple your pleasure Some notebooks let you double the power with a second battery that fits into a modular bay, nearly doubling runtime. A few systems can even take as many as three batteries, if you include the docking station, also called a media slice. The ThinkPad X200, for instance, can be fitted with a large-capacity battery in place of its standard one, and it has a connector for an additional bottom-mounted external battery. 6. Charge when you can Before leaving the home or the office with your notebook, fully charge all your batteries. If you're traveling, look around for a wall outlet to give your batteries a refresher charge when you can, because every little bit helps. Some third-party devices will help you charge on the road, such as iGo's Juice 70. This versatile device does it all: It's a regular AC adapter, as well as a car converter, and it will work on many airplanes. With the right plug, it can even charge your phone or handheld. 7. Check the CMOS battery If you have to reset your notebook's clock or your system BIOS, you might have a bad backup battery. Also called the CMOS battery, this secondary battery, which powers the clock when the system is not in use, can sap the main battery power if it's dead. The good news is that this battery is inexpensive. The bad news is that you'll likely have to dig around inside the system to find it. Some vendors put the backup battery under the memory chip slots, while others stash the CMOS battery under or next to the main battery. Check your manual or the vendor's technical support Web site for details. 8. Shut down unnecessary programs When you're running your notebook on battery power, turn off devices and programs you don't need. When not connected to a wireless hotspot, turn off the Wi-Fi hardware. If you access wireless networks with a PC Card, remove it when not connected. Listening to music via the CD-ROM drive and watching DVDs are also big battery drains. 9. Start with complete battery drains To ensure long-term battery vitality, do the following: When first using your notebook on battery power, let the battery completely drain before you recharge it. Don't recharge when the battery is only half drained. Do that for at least the first two sessions. Also, avoid temperature extremes. Don't leave a portable in a hot car or use it outdoors in extremely cold weather; hot batteries discharge very quickly, and cold ones can't create as much power. 10. Terminal care Make sure the battery contacts that connect your cells to the notebook are straight and clean and free of grime because the last thing you need is a bad connection. Most contacts are flat, copper-colored metal strips, but they may be hidden between pieces of protective plastic. Every six months or so, give the contacts a clean with a cotton swab and rubbing alcohol to remove electron-sapping dirt and grime. A bad connection can keep you from getting the most out of a battery.
How a battery worksBattery cellCells are individual cylindrical compartments in a battery that produce power. As many as 12 cells are used in a notebook battery. Capacity This refers to the amount of energy a battery contains. The typical laptop battery has between 2,000 and 6,000 milliamp hours (mAh) of capacity. Charge cycle This describes the complete charge and discharge cycle of the battery. Fully draining the battery then recharging it is one charge cycle. Degradation The process by which the chemicals in a battery lose their ability to hold a full charge. Discharge This describes using the power stored in a battery by chemically depleting the charge. Electrolyte This chemical carries electrons while the battery is being used. Energy density This term describes how much energy a battery contains based on its watt-hour capacity divided by its weight; many external batteries have between 100 and 200 watt-hours of energy. Fuel cell This refers to any of various devices that convert chemical energy directly into electrical energy. They are different from batteries because they use liquid fuel to produce electrical energy, whereas batteries use reversible chemical reactions. Lithium-ion battery These batteries use lithium for the negative electrode and offer high energy density and the ability to undergo repeated charge cycles. Lithium-polymer battery Similar to a lithium-ion battery, a lithium-polymer battery uses a conductive plastic and is more malleable than traditional lithium-ion batteries. Lithium polymer can be molded into different shapes, which can be critically important to the makers of small devices such as mobile phones. Memory effect (a.k.a. memory degradation) Not to be confused with computer memory, this is the loss of ability to fully recharge a battery, which happens over a long period of battery use. Milliamp hour This is the main battery capacity rating, equal to one-thousandth of an amp-hour, generally referred to by its acronym, mAh. The typical notebook battery has between 2,000 and 6,000 milliamp hours of capacity. Negative electrode This is the conductive part of the battery to which electrons flow. Nickel-cadmium battery Also known as NiCd, this was the original battery technology used in notebooks. In using cadmium as the negative electrode, these batteries have a relatively low energy density and suffer from memory effects. Nickel-metal-hydride battery By removing the cadmium and using nickel hydride instead, these batteries are made to hold more energy, but they can't be recharged more than a few hundred times. They are generally referred to as NiMH. Porous separator This permeable material or membrane separates the battery's two electrodes and allows current to flow from the positive to the negative electrode. Positive electrode This is the conductive part of the battery; electrons flow away from it. Rechargeable battery This is a battery that can be used repeatedly by adding power to it when the cells are drained. These batteries typically can go through a few hundred charge cycles before they start to lose the ability to hold a charge. Watt-hour A watt-hour is a measurement of the amount of energy held in a battery that can power a 1-watt device for 1 hour. Many external batteries have between 100 and 200 watt-hours of energy. |
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