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Finding Hidden Batteries 414 ability to hold a charge if it gets much hotter. Does this mean that keep- ing your laptop in the trunk of your car on a hot summer day isn’t a good idea? Yup. ✦ Remove the battery. If you’re going to use your laptop for an extended time while connected to an AC power source, turn off the machine and remove the battery. A LiOn battery generates heat (and shortens its life) if you charge it while the computer is in use with AC power. When you remove the battery from your laptop and run the machine on AC power, you’re adding one risk: If the power fails, you won’t have the battery ready to take over immediately and thus you will lose any unsaved work. If you’re at your desktop, consider adding an uninter- ruptible power supply. ✦ Avoid running your battery down to zero. It’s okay to do this from time to time, but don’t make it a regular habit. With a modern LiOn battery, it is better to have many partial discharges and recharges instead of con- stantly running it down to empty. (Older nickel cadmium batteries were just the opposite—they preferred full discharges and recharges.) ✦ Put a charge on. If you remove your battery to store it for a while, give it at least a 40 to 50 percent charge; certain types of laptop batteries can fail if they discharge all the way to zero. Check the charge level at the power utility on your taskbar. (When they’re in your machine, the built- in software monitor should give you enough warning to allow you to shut down with at least a bit of power still in the cell.) ✦ Don’t stock up. I stock our pantry with several dozen of each anytime the supermarket has a sale on canned soup and breakfast cereal, but the same doesn’t apply when it comes to laptop batteries. You’re better off buying fresh batteries from a reliable source just before you need them; ask about the manufacturing date before buying. If you have a spare LiOn battery, keep the extra one (with about a 40-percent charge) in a cool place. You can wrap it carefully in plastic (not aluminum foil, which could short it out) and place it in the refrigerator or another cool place. Give the battery a few hours to gradually warm to room temperature before attempting to use it or recharge it. Finding Hidden Batteries Most laptops have, in addition to the main battery, two other much smaller batteries buried deep within the box. Real-time clock The RTC, or real-time clock, is to maintain the internal clock . . . in real time. That is how the laptop knows the time as well as the date whenever you turn 30 140925-bk06ch01.qxp 4/8/08 12:49 PM Page 414 Book VI Chapter 1 Using Your Power for Good Purposes Finding Hidden Batteries 415 on the machine. It also has another purpose: to provide a trickle of power to the computer’s setup information, which is recorded in a special form of memory called CMOS (non-volatile) memory. The little RTC battery is recharged from the main battery and should keep time and hold power for at least a month all by itself (without power from the AC adapter or from the main battery). For that reason, if your laptop is going to sit unused for an extended period of time (several months or more) you should top off the main battery every month or so. Or you can keep the laptop plugged into an AC source while it is on the shelf. An RTC battery should last three to five years or more; that’s the good news. The bad news is that on nearly every modern laptop, the RTC isn’t some- thing a user can replace. If the battery fails (you may see an error message at startup, or find that the clock or the setup configuration becomes flaky, cor- rupted, or otherwise odd), you have to arrange for factory service. Backup battery This rechargeable battery, common on many but not all laptop designs, pro- vides enough power to keep the computer’s volatile memory (RAM) alive when the computer is in Standby mode. Also charged by the main battery or the AC adapter, the backup battery usu- ally holds data and settings in computer memory for several days (to a week or so) after the main battery has been fully discharged. Like the RTC battery, the backup battery should be good for three to five years or more, and mere mortals aren’t to replace it. The laptop has to go to the repair shop if it fails. You can use a laptop without a functioning backup battery — you just won’t be able to use Standby mode once the main battery has given all it has to give. 30 140925-bk06ch01.qxp 4/8/08 12:49 PM Page 415 Book VI: Managing Your Power Supply 416 30 140925-bk06ch01.qxp 4/8/08 12:49 PM Page 416 Chapter 2: Replacing or Upgrading Your Power Source In This Chapter ߜ Power trips and tips ߜ Replacing or upgrading a battery ߜ Alternate sources of power for the road warrior W elcome, cellmates. Our power to travel cordlessly is linked to the output of your laptop’s rechargeable battery. The following are the facts of life, at least as it relates to batteries: ✦ Some batteries are more powerful than others. ✦ Some batteries can hold a charge longer than others without being attached to wall current. ✦ Some batteries can better withstand repeated charges and discharges than others. ✦ All batteries will die. Some will stop suddenly and some will fail over time. The good news is that batteries are a portable device all by themselves. You can replace them when the fail, and depending on your laptop model, you may be able to upgrade them or install a second battery. Measuring Battery Capacity and Power Without getting too deep into the details of electricity you can measure these things: ✦ Voltage. One volt is defined as the amount of pressure required to push one amp of current against one ohm of resistance. In electrical terms, this is the amperage. ✦ Wattage. This number tells you the total amount of work you can do with the battery. Multiplying voltage times amperage calculates wattage. In your home or office, your electric company calculates your bill on the basis of kilowatts per hour, which is a measurement roughly equivalent to using 1,000 watts of power for an hour. (For example, a 100-watt light bulb 31 140925-bk06ch02.qxp 4/8/08 12:49 PM Page 417 Measuring Battery Capacity and Power 418 burning for 10 hours consumes 1 kilowatt.) Laptop computers use power in smaller quantities, typically demanding somewhere between 35 and 75 watts of peak draw. (Peak draw might occur in this situation: The LCD is fully lit, the graphics adapter is drawing constantly changing, complex images derived from a DVD, a whole bunch of RAM is being powered, the hard disk drive is spinning, and the WiFi adapter is switched on.) Battery wattage or amperage When it comes to the bucket of power called a battery, we’re not quite at the point where a small, lightweight laptop can have access to a kilowatt or more of stored power. Instead, we talk about watt hours or sometimes amp hours. One watt hour (WHr) is the amount of electric energy required to power a 1-watt load for an hour. A laptop that draws an average of 20 watts per hour runs for about two hours on a fully charged battery rated at 40 WHr. Another way to rate a battery is to express its capacity in amp hours (AH). Amp hours are like the explosive potential of a tank of gas, while watt hours represent the distance that power can drive the car. To convert watts to amps, use this formula: watts / volts = amps You may see amp hours expressed like this: 4.4 AH. Or some techie may prefer to rate the same battery as 4400 mAH. (An mAH is a milli-amp hour, and 4,400 milli-amp is the same as 4.4 AH.) Batteries offered today usually range in capacity from about 25 WHr to as much as 96 WHr. An ordinary range of amp hours for laptop batteries is from about 4 to 8. When it comes to choosing a battery, watt hours or amp hours are really the only number (other than the weight) to which you need to pay attention. A larger capacity is better than a smaller bucket of juice . . . and heavier. Battery weight The more watt hours a battery produces or amp hours it contains, the longer the laptop can operate. You’d think, then, that the solution was oh-so-simple: Get as many as you can. The problem is that batteries require metals and chemicals to hold a charge, and the greater the capacity, the heavier the device. 31 140925-bk06ch02.qxp 4/8/08 12:49 PM Page 418 Book VI Chapter 2 Replacing or Upgrading Your Power Source Replacing the Battery 419 The manufacturer may tell you that a battery has four cells, six cells, nine cells, or almost any number of cells. The more cells of a particular technol- ogy, the more space for stored energy, but the news you can use is the WHr or the AH rating. Replacing the Battery For many users, the laptop becomes technologically outdated or starts to have other problems after about four years. If the battery fails or no longer holds a sufficient charge, you can easily replace it. Even if you can no longer use an older laptop, try to remember others: A school or individual might find your outdated machine very useful. Prices for laptop batteries usually range from $50 to $150. ✦ Start with your laptop manufacturer’s web site or telephone sales department. Get a price for a replacement, and make sure you find all the warranty details. ✦ Check the Internet for third-party battery suppliers. You may find the identical name-brand battery for less. And you may also be offered Brand X replacements at a significantly lower price; some of the third- party batteries even promise to hold a larger charge. Personally, I’ve had no problems using generic batteries. However, I would pay close atten- tion to the warranty; what happens in the one-in-a-million-or-so situation where a battery overheats or otherwise damages your laptop? Breeding hybrids Scientists are hard at work developing new hybrid metals and electrolytes (literally, the juice within the battery) that can hold more power without turning into an electronic cinder block. The current champion—at least for con- sumer-grade products—is Lithium Ion (LiOn) technology. Other designs in the labs include polymer-based alkaline, lithium nickel man- ganese oxide, lithium cobalt oxide, and Spam in a Can. Okay, I made that last one up, although it probably could generate gas one way or another. 31 140925-bk06ch02.qxp 4/8/08 12:49 PM Page 419 Replacing the Battery 420 Here’s how to replace the battery: 1. Turn off your laptop and disconnect the AC adapter. 2. Release the latch or other attachment devices that hold your battery in place. See Figure 2-1. Courtesy Toshiba America, Inc. 3. Slide the old battery out of its compartment or storage bay. See Figure 2-2. Avoid touching the contacts on the battery itself or inside the bay; the oils on your fingertips could reduce the conductivity of the battery. 4. Take the replacement battery out of the box. 5. Slide it into the notch or bay. See Figure 2-3. 6. Close the safety latch to lock it into place. 7. Reconnect the AC adapter and give the battery a full charge. Figure 2-1: Many laptops include a latch that locks the battery into place; this safeguards against it being accidentally dislodged or left behind. 31 140925-bk06ch02.qxp 4/8/08 12:49 PM Page 420 Book VI Chapter 2 Replacing or Upgrading Your Power Source Replacing the Battery 421 Courtesy Toshiba America, Inc. Courtesy Toshiba America, Inc. Figure 2-3: Installing a new battery. Figure 2-2: Press the release button if there is one and carefully lift the battery out of its com- partment. 31 140925-bk06ch02.qxp 4/8/08 12:49 PM Page 421 Mining Other Sources of Power 422 That’s about as simple a repair as you’re going to find on a laptop. You need to know these things when replacing a battery: ✦ Meet the specifications. You can’t squeeze a 3-inch battery made for a Dell laptop into the 2-inch slot on a Toshiba. It’s physically impossible, and even if you could squeeze it in, the electrical connectors probably wouldn’t line up. ✦ Match the voltage. If your original battery was rated at 14.8 volts, that’s the ticket for the replacement model. Don’t go over or under the speci- fied power. ✦ Consider going high capacity. Within the manufacturer’s specifica- tions, you may be able to replace your original battery with one with a higher watt hour or amp hour rating. This allows you to work longer and harder . . . and give your muscles a bit of extra exercise when you lug the laptop. ✦ Get fresh. You’ve no good reason to buy a used battery (or an unused model that has been collecting dust on a shelf somewhere). Check the date of manufacture; I consider anything older than about 18 months to be suspect. (It’s like the unidentified frozen meat that’s been in the back of the freezer for longer than you can remember; it may be fine, it may have lost its ability to please, or it may make you sick. Don’t take the chance.) Mining Other Sources of Power Someday we’ll be able to deliver power to our laptops with tiny fuel cells or magic pills. A global effort exists to provide simple little machines to third- world children (the One Laptop Per Child initiative, at http://laptop.org) that you can power up by a hand crank or foot pedal. But most of you are tied to an electrical outlet at one point or another: either to run your laptop in the office, or to recharge the internal battery for use on the road (or in the air or in the park). A few alternates can bring power from sources other than a wall outlet and I’m going to avoid the subject of personal windmills, sewing machine tread- les, and pocket-sized nuclear reactors. Adding a second internal battery Certain laptop models — generally larger and more sophisticated systems — offer a multipurpose bay on one side or the other of the bottom box to hold a secondary rechargeable battery (or an extra hard disk drive or CD/DVD drive or other device). 31 140925-bk06ch02.qxp 4/8/08 12:49 PM Page 422 Book VI Chapter 2 Replacing or Upgrading Your Power Source Adapting to Plane and Car 423 This second battery is usually smaller than the main battery, which means that it holds less energy. Depending on the model, though, it should add from one to three hours of extra life . . . and close to a pound of weight. Adding an external battery It’s not the most elegant— kind of the computer equivalent of adding a side- car to a motorcycle or training wheels to a bicycle — but another solution is to purchase and use an external, or auxiliary, battery. This device is commonly a small, pizza-box-like unit that sits beneath your laptop and connects to its standard power port. A second device is like a brick that sits alongside your laptop or on the floor. These batteries come in a range of capacities, including models that meet or exceed the stored power of the main battery. Most include an electronic circuit that automatically adjusts the output voltage to your machine’s needs and a set of converter tips that allow them to mate with laptops of differing designs. You may also find external bat- teries specifically designed to work with your particular model. These external batteries typically cost a bit more than a standard main bat- tery because they include their own charger and because they may hold a higher capacity. And they add between 1 and 2 pounds to your load and take up almost as much space in your carry-on bag as the laptop itself. Adapting to Plane and Car As a modern road warrior, if I’m not at my desk, in a hotel, or on a cruise ship, I’m probably in a car or on an airplane. The laptop’s internal batteries come in handy at these places . . . for as long as they last. You have several ways to operate your computer or recharge batteries (or both) while in a car or airplane. Powering up in the air Some airlines, on some planes, offer power to the people at some seats. If this sounds a bit iffy, that’s because it is; you can’t predict with any certainty whether a particular plane will offer this feature. A few airlines promote this service on certain long-distance flights that cater to businesspeople. The most common design is a system called EmPower, which delivers DC current; you need a special adapter (available from either your laptop manu- facturer or from a third party) to connect to your machine. Some airlines offer DC power through circular outlets just like the ones you find in automobiles. And a handful of planes come equipped with 110 volts of AC power to some or all seats. (Some commuter and long-distance trains offer AC outlets.) 31 140925-bk06ch02.qxp 4/8/08 12:49 PM Page 423 . Power for Good Purposes Finding Hidden Batteries 415 on the machine. It also has another purpose: to provide a trickle of power to the computer’s setup information, which is recorded in a special form. time and hold power for at least a month all by itself (without power from the AC adapter or from the main battery). For that reason, if your laptop is going to sit unused for an extended period of. to using 1,000 watts of power for an hour. (For example, a 100-watt light bulb 31 140925-bk06ch02.qxp 4/8/08 12:49 PM Page 417 Measuring Battery Capacity and Power 418 burning for 10 hours consumes 1

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