284 lines
7.9 KiB
HTML
284 lines
7.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>Types of Batteries</TITLE
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>Battery Powered Linux Mini-HOWTO</TH
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><A
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NAME="BATTERY"
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></A
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>4. Types of Batteries</H1
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><P
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>There are currently three types of batteries commonly used for
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laptops: Nickel Cadmium, Nickel Metal Hydride, and Lithium Ion.</P
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
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><A
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NAME="NICD"
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></A
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>4.1. Nickel Cadmium (Ni-Cd)</H2
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><P
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>Nickel Cadmium (Ni-Cd) batteries were the standard technology for years,
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but today they are out of date and new laptops don't use them anymore. They
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are heavy and very prone to the "memory effect". When recharging a NiCd
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battery that has not been fully discharged, it "remembers" the old charge and
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continues there the next time you use it. The memory effect is caused by
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crystallization of the battery's substances and can permanently reduce your
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battery's lifetime, even make it useless. To avoid it, you should completely
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discharge the battery and then fully recharge it again at least once every few
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weeks. As this battery contains cadmium, a toxic material, it should always
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be recycled or disposed of properly.</P
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><P
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>NiCad batteries, and to a some degree NiMH batteries, suffer from what's
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called the <EM
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>memory effect</EM
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>. Memory Effect means that if a
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battery is
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repeatedly only partially discharged before recharging, the battery will
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forget that it can further discharge. The best way to prevent this situation
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is to fully charge and discharge your battery on a regular basis.</P
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></DIV
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
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><A
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NAME="NIMH"
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></A
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>4.2. Nickel Metal Hydride (Ni-MH)</H2
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><P
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>Nickel Metal Hydride (Ni-MH) batteries are the cadmium-free replacement
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for NiCad. They are less affected by the memory effect than NiCd and thus
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require less maintenance and conditioning. However, they have problems at
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very high or low room temperatures. And even though they use less hazardous
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materials (i.e., they do not contain heavy metals), they cannot be fully
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recycled yet. Another main difference between NiCad and NiMH is that NiMH
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battery offers higher energy density than NiCads. In other words, the capacity
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of a NiMH is approximately twice the capacity of its NiCad counterpart. What
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this means for you is increased run-time from the battery with no additional
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bulk or weight.</P
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></DIV
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
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><A
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NAME="LIION"
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></A
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>4.3. Lithium Ion (Li-ion)</H2
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><P
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> Lithium Ion (Li-ion) are the new standard for portable power. Li-ion
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batteries produce the same energy as NiMH but weighs approximately 20%-35%
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less. They do not suffer significantly from the memory effect unlike their NiMH and Ni-Cd
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counterparts. Their substances are non-hazardous to the 0. Because
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lithium ignites very easily, they require special handling. Unfortunately,
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few consumer recycling programs have been established for Li-ion batteries at
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this point in time.</P
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></DIV
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
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><A
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NAME="SMART"
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></A
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>4.4. Smart Batteries</H2
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><P
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><EM
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>Smart</EM
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> batteries are not really a different type of
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battery, but they do deserve special mention. Smart batteries have internal
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circuit boards with chips which allow them to communicate with the
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laptop and monitor battery performance, output voltage and temperature.
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Smart batteries will generally run 15% longer due to their increased
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efficiency and also give the computer much more accurate "fuel gauge"
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capabilities to determine how much battery run time is left before the next
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recharge is required.</P
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></DIV
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
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><A
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NAME="BATCOMP"
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></A
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>4.5. General Battery Care</H2
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><P
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>Even if the battery case looks the same, you cannot just upgrade to
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another battery technology unless your laptop has been pre-configured from the
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manufacturer to accept more than one type of battery type, since the recharging
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process is different for each of the three types of batteries.</P
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><P
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>A battery that is not used for a long time will slowly discharge itself.
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Even with the best of care, a battery needs to be replaced after 500 to 1000
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recharges. But still it is not recommended to run a laptop without the battery
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while on ac power -- the battery often serves as a big capacitor to protect
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against voltage peaks from your ac outlet.</P
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><P
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>As the manufacturers change the shapes of their batteries every few
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months, you might have problems to find a new battery for your laptop in a few
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years from now. This is somewhat of a concern only if you anticipate using the
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same laptop several years from now. If in doubt, buy a spare battery now -
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before it's out of stock.</P
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><P
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>New batteries come in a discharged condition and must be fully charged
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before use. It is recommended that you fully charge and discharge the new
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battery two to four times to allow it to reach its maximum rated capacity. It
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is generally recommend that you perform an overnight charge (approximately
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twelve hours) for this. Note: It is normal for a battery to become warm to the
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touch during charging and
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discharging. When charging the battery for the first time, the device may
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indicate that charging is complete after just 10 or 15 minutes. This is a
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normal with rechargeable batteries. New batteries are hard for the device to
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charge; they have never been fully charged and are not broken in. Sometimes the
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device's charger will stop charging a new battery before it is fully charged.
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If this happens, remove the battery from the device and then reinsert it. The
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charge cycle should begin again. This may happen several times during the
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first battery charge. Don't worry; it's perfectly normal. Keep the battery
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healthy by fully
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charging and then fully discharging it at least once every two to three weeks.
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Exceptions to the rule are Li-Ion batteries which do not suffer from the
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memory effect.</P
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><P
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>Batteries should be stored in a discharged state since they
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can self-discharge and may become inactive after a long storage period. They
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should not be stored for any length of time while connected to the laptop.
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High humidity and temperatures can cause the battery to deteriorate, so these
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should be avoided during storage.</P
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><P
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>Do not remove and carry a battery pack in your pocket, purse, or other
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container where metal objects (such as car keys or paper clips) could
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short-circuit the
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battery terminals. The resulting excessive current flow can cause extremely
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high temperatures and may result in damage to the battery pack or cause fire
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or burns.</P
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