... although Acer is one of the OEMs testing/qualifying Saphion technology, Steve ...
PC Magazine - October 15, 2002
small portion about VLNC is highlighted
A Long and Happy Life for Notebooks
October 15, 2002 by Bill Howard
The $150 lithium ion battery is a marvel of compact packaging—the result of countless hours of R & D work in labs around the world. Its power production involves a chemical reaction just like the one that goes on inside your car battery, albeit with more exotic materials than lead and acid. But unlike transistor count, battery capacity does not follow Moore's Law; there's no doubling every 18 months. It's a very good year when battery performance increases 5 percent.
Battery life in notebooks has increased more from the creation of components that use less power than from efforts to make batteries store more energy. In fact, as battery performance has increased, notebook makers have scaled back battery size to save weight. Batteries weighing more than a pound weren't uncommon a decade ago. Now many are down to 10 or 12 ounces. These batteries provide around 2 hours of power, which works for most of us because we tend to use laptops unplugged for short intervals.
To maximize battery life, you need to follow three guidelines: buy right, treat your batteries well, and take advantage of power conservation tricks. These tips will help you squeeze an extra 20 to 25 percent of life from each battery charge. A typical Pentium III–based system consumes 10 to 15 watts most of the time, so scaling back 1 watt could increase battery life by roughly 7 to 10 percent.
Of course, if you want a machine to last 6 or 10 hours, you need a laptop that can take a second or third battery.
Buy Right
If you're about to buy a notebook, look for a machine with the ultra-low-voltage Mobile Intel Pentium III Processor-M. The Mobile Intel Pentium 4 Processor-M draws more peak power—the power used when performing many operations at the highest speed and voltage—so it is bulkier and requires more cooling. On the other hand, it works faster and returns to a low-power state more quickly, so its overall power consumption isn't very different from that of the PIII-M. Both have SpeedStep technology, so the CPU scales its frequency and voltage according to how much processing power is needed. The P4-M can draw 30 watts at peak, but it drops its power draw in milliseconds (sometimes between keystrokes) and keeps its idle draw to 2 watts.
The least desirable choice for mobile users is the desktop Pentium 4 (note that there's no -M in the chip name), which is on a couple of big, low-cost notebook PCs. Using the desktop part cuts $100 off the price of a notebook, but the battery drain is significantly worse.
Intel isn't the only game in town. AMD has a line of low-power mobile processors, and Transmeta makes low-power processors exclusively.
As users demand desktoplike graphics performance, the graphics chip set becomes a bigger power drain. A high-power chip set with lots of memory can consume up to a quarter of the total power used. If you want to save battery strength, look for a system with a lower-performance graphics chip set (such as those embedded in the system chip set). Look for discrete chip sets with SpeedStep-like technology, such as the ATI Mobility Radeon 7500 or Mobility Fire GL 7800, or the nVidia GeForce2 Go or GeForce4 Go.
In 2003, Intel will produce an even-lower-power variant of the P4 (and a related chip set) code-named Banias. This will give better battery life, but at a premium price and with lower speeds than non-Banias P4s.
Many current notebooks come with built-in wireless Ethernet (also called Wi-Fi or 802.11b). This is a great convenience but another drain on the battery. Look for models with Wi-Fi switches on the chassis. A Fujitsu or HP notebook, for instance, has both a switch and an indicator light, so it's hard to forget when wireless is running. More prevalent and harder to use are software controls (look for a wireless icon in the tool tray) and function-key combinations.
Finding a machine that runs an OS other than Windows XP (or Windows 2000 in business) is hard now, and that's good for battery life. Win XP is close to flawless at putting a system into standby when you close the lid or tap the power button and then, after about 3 hours, dropping into hibernation. Windows 98 often failed to go into suspend when you closed the lid. If you're running Windows 98, you might want to think about upgrading to Win XP—but first run a compatibility check (www.microsoft.com/windowsxp) to verify that your notebook is upgradable.
A great way to get more use out of your notebook on battery power is to use a two-bay system such as the Dell Latitude 610, the IBM ThinkPad T23 or T30, or the Toshiba Portégé 4010 or Tecra 9100. These let you replace the CD or DVD drive with a second battery, giving you battery life of from 5 to 7 hours. Many of the 3-pound mini-notebooks with single bays, such as the Dell Latitude C400 and the Toshiba Portégé 2000, have battery-only undermount slices that more than double battery life, and others have heavier docking slices that hold a drive and a second battery. Unfortunately, the bay battery for most machines is different from the main battery; a handful of Sony notebooks (the GR, GRX, and FXA) use the same design for both.
Be careful of notebooks sold with weight-saver batteries—a euphemism for batteries stuffed with air. The system maker can cut the price by $25 to $50, but the weight savings is no more than a quarter pound. Conversely, you can buy larger, extended-life batteries (for notebooks from Fujitsu, Gateway, and Sony, among others), but they stick out the front or back of the laptop by an inch. If you have a fitted case, your notebook will no longer fit.
If you need an additional 5 to 10 hours of battery life, check out the Electrovaya (formerly Electrofuel) PowerPad ($400 to $500 street, www.electrovaya.com), or the Valence N-Charge ($350 to $500 street, www.valence.com). These are lithium ion batteries that have adapters for most popular notebook brands. They plug into the transformer jack and recharge using your laptop's existing charger.
Generally, you can trust a vendor's battery life claims. Most of them use the Ziff Davis BatteryMark test, which is accurate to within 10 or 15 minutes if run properly. At the least, you'll know if you're getting a 2-, 3-, or 4-hour notebook. A good notebook should last 3 hours on the test.
Treat Your Batteries Right
The lithium ion batteries used in all but the cheapest notebooks don't suffer from the memory effect that hampered first-generation (nickel cadmium) and, to a lesser extent, second-generation (nickel hydride) batteries. A battery suffering from memory effect is unable to charge fully if it was not completely discharged before being charged previously.
According to some researchers, though, lithium ion batteries also benefit from a full discharge followed by a full recharge every three months. To achieve full discharge, you must disable the triggers that put the system into standby at 10 percent battery life and into hibernation at 3 percent. You want to run the battery down to 0.
Under Windows XP, do this: Click on Control Panel | Performance and Maintenance | Power Options | Alarms. Make sure the actions for both Low Battery Alarm and Critical Battery Alarm are unchecked (set Action to No action). To speed up rundown, you may want to put the system into full-power mode. Set the screen to full brightness and disable screen blanking. Once it's completely drained, recharge the battery overnight and return the alarms to their original settings.
If you need replacement batteries, consider buying the manufacturer's branded battery ($150 to $200, typically). Obviously, system makers want to dissuade you from buying third-party equipment, just as printer companies want to prevent you from buying toner and ink from others. But batteries are complex devices; most contain microprocessors, and a unit that shorts or improperly charges can cause injury.
Be sure your notebook is fully charged before you use it for an extended period away from AC power. If you haven't used it for a few days, make sure you recharge it. A lithium ion battery self-discharges over two to three weeks. A system left in suspend mode uses about 15 percent of its battery power daily for tasks like refreshing the memory. That trickle of current kills the battery in about a week. If you want to leave your notebook in a suspended state for long periods, use hibernation, which writes the current system image out to disk, then shuts down the machine. The downside of putting a notebook into hibernation is that it needs more time to wake up. A 384MB IBM ThinkPad T20 we tested required 47 seconds to come out of hibernation, versus only 7 seconds to restore from suspend.
There is no disadvantage to keeping your notebook plugged in all the time; the battery won't wear out any faster. Do check occasionally that the battery isn't overheating. A hot battery won't take a charge readily. If the battery is hot and won't charge, unplug the system, let the battery cool, and try again. If the battery still overheats—meaning it's almost too hot to touch—you may be ready for a replacement.
Batteries wear out eventually. After roughly 500 charge/discharge cycles, you'll probably get only 75 percent of the life it had when it was new.
If you use your notebook on battery power for just a few minutes, it may not recharge when you reattach the power cord. To prevent overcycling the charging circuitry (which could hurt battery longevity), most systems recharge only if the battery is below 95 percent of a full charge. Thus, if your transformer/battery status icon in the tool tray has read 98 percent for the past half day, that's okay. Also, don't stop charging when the charge light goes off. Often, you're only at 80 percent instead of 100 percent.
Power Conservation Tips
You can probably stretch your rundown time by 30 to 45 minutes with thoughtful use of power conservation settings.
The most effective way to increase battery life is to turn down the brightness of the display. Going from dimmest to brightest adds 3 to 5 watts of draw, a noticeable amount in a system drawing around 10 to 20 watts.
Make sure your notebook's power management is enabled. Set it for Battery optimized mode, or Max battery (generally the default settings in Control Panel's Power Options section if you're running Windows XP).
If you're not in the office, not in an Internet café, and not in one of the nation's few high-tech airports, turn off wireless Ethernet. That's worth a watt. Even sitting idle, Wi-Fi can contribute to battery drain. Transmitting is the worst; receiving is the next-worst. Disable wired Ethernet, too. You can access settings for both from the system tray. You can get very marginal savings by turning off parallel and serial ports, but this can cause OS problems in older versions of Windows.
Remove any accessories from PC Card slots, especially wireless Ethernet adapters (the older the adapter, the more power-hungry it is), along with hard drive cards and USB and SCSI adapters. Don't worry about digital camera memory cards (CompactFlash, Memory Stick) or self-powered devices attached to USB ports.
Oddly, having more memory (384MB or 256MB instead of 128MB) helps battery life. The additional power needed to refresh the RAM is less than the savings gleaned from spinning the hard drive less often. To make the most of the RAM you have, close programs you're not using.
If you have confidence in the operating system not crashing, you can disable auto-save of your data files, or change the interval to every 30 minutes. Also, put your audio on mute to save part of a watt. Using these tips, you should see a noticeable increase in your battery's longevity.
Eleven Ways to Extend Battery Life
With determined effort, you can extend battery life by 20 to 25 percent. Steps 1 and 2 alone get you halfway there.
Turn down the LCD brightness.
Use built-in power management.
Turn off wireless and wired Ethernet when not in use.
Set screen blanking to 1 or 2 minutes.
Add RAM.
Close unused programs.
Fully drain, then recharge lithium ion batteries every few months.
Remove unused PC Cards.
Removed unused notebook-powered USB devices.
Avoid "weight-saver" batteries.
Don't watch DVDs, and don't play graphics-heavy games.
Copyright (c) 2002 Ziff Davis Media Inc. All Rights Reserved. |
