The simple fact of notebook life is that systems simply don't run for as
long on their batteries as I'd like even long-lived notebooks, such as
Sony's VAIO VGN-TX27GP, last only 5.5 hours on a single battery.
To help you make smart decisions about the notebooks you buy and the way
you use them, I demystify today's battery technologies and examine the
fuel cell technology that might power your next notebook. I'll also
provide 10 tips for getting the most out of your system's current
battery, along with a glossary of key terms.
We can't make a battery last forever, but we can help to make sure that
you get the most out of every electron.
Battery technologies explained With 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 notebook design.
Unfortunately, NiCd cells can only carry enough power to run a system
for about an hour, and they contain toxic cadmium, which makes them hard
to dispose of.
And 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 them only about 200 times versus 400
charge cycles for newer designs. 2
Chemistry
Peak watt-hours / number of recharges
Problems
Main use
Nickel-cadmium (NiCd)
80 / 1,000
Heavy for the power it holds, memory effects, contains toxic elements
Toys, cordless phones
Nickel-metal-hydride (NiMH)
120 / 200
Moderate weight for power, limited lifespan
Rechargeable batteries, older notebooks, mobile phones
Lithium-ion (Li-ion)
160 / 400
Hard to manufacture, expensive
Notebooks, handhelds
Lithium-ion polymer (Li-poly)
130 / 400
Hard to manufacture, expensive
Mobile phones and backup batteries
Fuel cell
N/A
Experimental, expensive
Space shuttle, power plants, automotive research
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 notebooks, 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.
Coming soon Look for lithium-polymer (Li-poly) technology to make its
way into mobile phones, handhelds and notebooks in the near future.
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. For a look at another battery
technology, check out the next section on fuel cells.
Batteries versus fuel cells The traditional battery's days may be
numbered. Thanks to recent advances in fuel-cell technology, your next
notebook (or maybe 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 notebook that
could provide a mind-boggling 40 hours of battery life. 3
NEC is developing a fuel-cell notebook. This is a prototype
and I'm unsure if or when it will hit the market.
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, senior
research manager overseeing NEC's project to create a fuel cell-powered
notebook (prototype pictured above).
Methanol, or methyl alcohol, is NEC's fuel of choice, and Kubo has
created a prototype notebook that can run for five hours on about a pint
of 10 percent fuel. 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 carrying a bagful of
batteries on a long flight, all you'd 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 miniaturisation 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 By 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 a AA battery,
the fuel cell contains 57g of 20 percent methanol fuel, and it powers a
handheld computer for 6 to 8 hours. Before its planned launch (which was
originally slated for 2005 but has since been pushed back), the
companies will try to boost runtime by using 30 percent methanol fuel,
making a 12-hour handheld a distinct possibility.
All this 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". Despite this, he says 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 batteries goodbye, along with the
eternal search for a power outlet to charge them -- although finding
fuel may create another problem.
Power and performance The notebook 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 Duo and Centrino technology, for instance,
notebooks can run faster and longer on the same batteries they used to
use. Here's the low-down on which processors let notebooks last the
longest. 4
Intel Core Duo (part of the Centrino Duo package) Without a doubt, the
Core Duo is the battery-life champ. With two processor cores, two
megabytes of Level 2 cache, 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 Duo is part of the
Centrino Duo triad.
Running at up to 2.16GHz, Core Duo notebooks run rings around the
competition, and many offer over four hours of battery life.
Intel Core Solo Intel's Core Solo processor is very similar to the Core
Duo, however, it uses single as opposed to dual processor cores. This
results in decreased raw performance, but it also means that the chip
consumes less power -- 5.5-27W compared to the Core Duo's 15-31W. The
Core Solo runs at speeds of up to 1.83GHz
AMD Turion 64 X2 The Turion 64 X2 is the Core Duo's main competitor.
Like Intel's version, it offers two processor cores for increased
performance whilst multi-tasking. It also boasts AMD's PowerNow! power
management technology, which AMD says can extend system battery life by
up to 65%. Built-in anti-virus protection is included, and the processor
comes in speeds up to 2GHz. Its power consumption is slightly higher
than that seen on Core Duo processors, and ranges between 31 and 35
watts.
AMD Turion 64 The Turion 64 is a cut-down version of the Turion 64 X2.
It offers all of the same features as the X2, but like Intel's Core
Solo, only includes a single processor core. Its power consumption
ranges between 25 and 35 watts, with speeds up to 2.4GHz.
Ten tips for the power-hungry With a little power conservation and some
smart moves, you can greatly improve your notebook'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 screen notebook with the top-speed processor -- it
probably won't run for more than two hours. When you're buying your next
notebook, think small and consider an ultra-portable or a thin-and-light
system. An Intel Core Duo processor uses about half as much power as a
Pentium 4, a 12.1in. 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 notebook goes to sleep too soon, adjust the settings. 5
Adjusting power and other options in the Power Options Properties
dialogue will improve your battery life.
3. Dim all the lights Your LCD's backlight uses up to 10 watts of power,
a huge battery drain. Lower the screen'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 notebooks, such as Apple's MacBook Pro, adjust
the screen'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 notebook 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 up 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 IBM ThinkPad X41,
for instance, can be fitted with a large-capacity battery in place of
its standard battery, 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 of your batteries. If you're 6
travelling, 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 may 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 hot spot, 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
notebook 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-coloured metal strips, but they might be hidden between pieces of
protective plastic. Every six months or so, give the contacts a cleaning
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 works 7
Battery cell Cells 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 notebook battery has between 2,000 and 6,000 milliamp hours
(mAh) of capacity. See milliamp hours.
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. See memory effect.
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-ion-polymer battery Similar to a lithium-ion battery, a
lithium-ion-polymer battery uses a conductive plastic and is more
malleable than traditional lithium-ion batteries. Lithium-ion polymer
can be moulded 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 the 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. 8
Negative electrode This is the conductive part of the battery to which
electrons flow.
Nickel-cadmium battery Also known as NiCd, this is 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 one-watt device for one hour. Many external
batteries have between 100 and 200 watt-hours of energy
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